Pl. 1. The Connecticut Valley as it is seen from Mount Sugarloaf.

The western highland shows through the pine boughs at the extreme right. The eastern highland balances it on the far left. The Holyoke Range hems the basin on the south except at the gap where the river escapes to the Springfield area.

The Flow of Time
IN THE
CONNECTICUT VALLEY

Geological Imprints

by
GEORGE W. BAIN
and
HOWARD A. MEYERHOFF

The Hampshire Bookshop
BOOKSELLERS AND PUBLISHERS
NORTHAMPTON, MASS.
1942

[Introduction] ix [Today and Yesterday] 1 [The River Works] 1 [The Landscape Changes] 4 [Glaciers Came] 8 [Just Before the Ice Age] 9 [Rivers Carried off the Everlasting Hills] 11 [Before the Rivers Cut the Valleys] 14 [The Mosaic of Central Massachusetts] 18 [The Red Rock Basin] 18 [A Dinosaur Diary] 21 [Volcanoes] 23 [The Original Valley] 28 [Hot Springs in Central Massachusetts] 30 [The Marginal Uplands] 30 [The Eastern Upland] 32 [Coal Swamps in Massachusetts and Rhode Island] 33 [The Western Upland] 34 [The Story of Central Massachusetts] 38 [Interesting Places] 51 [Mount Lincoln in Pelham] 51 [Mount Toby] 52 [The Sunderland Caves] 55 [Mount Sugarloaf] 56 [Turners Falls] 58 [The French King Bridge] 59 [Titan’s Piazza and Titan’s Pier] 60 [Westfield Marble Quarry] 61 [The Old Lead Mines] 63 [The Dinosaur Tracks near Holyoke] 66 [Fossil Fishing] 68 [Calendar Beds] 69 [The Holyoke Range] 70 [Trips from Northampton] 78 [Northampton, Amherst, Pelham] 78 [Belchertown, Amherst and Northampton] 82 [South Hadley, Amherst, Northampton] 83 [Holyoke, Easthampton, Northampton] 85 [Northampton, Hadley, Sunderland, Hatfield] 86 [Northampton, Cummington, Plainfield and South Deerfield] 88 [Trips from Greenfield] 91 [Mohawk Trail, Adams, Plainfield and South Deerfield] 91 [Greenfield, Orange, Pelham, Amherst and Deerfield] 96 [Greenfield, Turners Falls, Montague, North Amherst] 99 [Greenfield, Turners Falls, Montague, Sunderland] 100 [Trips from Springfield] 102 [Springfield, Holyoke, Easthampton and Westfield] 102 [Westfield to the Westfield Marble Quarry] 104 [Optional Trips] 105 [Mineral and Rock Collections] 106 [The Minerals] 107 [The Vein Minerals] 107 [Minerals of Pegmatites and Igneous Rocks] 109 [Minerals of Metamorphic Rocks] 111 [The Minerals of Soils and Rock Decay] 111 [The Minerals of Sedimentary Rocks] 111 [The Rocks] 112 [The Sedimentary Rocks] 113 [The Igneous Rocks] 114 [The Dark Rocks] 115 [The Medium-Colored Rocks] 116 [The Light-Colored Rocks] 116 [The Metamorphic Rocks] 117 [Conclusion] 120 [Indexes] 121

Plates

[1. The Connecticut Valley as it is seen from Mt. Sugarloaf] Front. [2a. Air view of the ox-bow lake between Northampton and Mt. Tom] 4 [2b. Roches moutonnées of the Pelham Hills seen from Hadley] 4 [3a. Mt. Sugarloaf, a remnant of Triassic rocks disappearing grain by grain down the Connecticut River] 12 [3b. Mt. Monadnock, a hill surmounting the New England peneplain, seen from Mt. Lincoln] 12 [4a. A dinosaur walked from the raindrop marked surface at the right to a shallow pond at the left] 22 [4b. Volcanoes ejected much ash and many bombs to form the Granby tuff] 22 [5a. Columnar lava rests upon red sandstone in the cliffs at Greenfield] 32 [5b. Fissures were filled with liquid rock that became solid and bonded wall to wall at the Windsor Dam] 32 [6. View of the Holyoke Range from Mt. Lincoln] 52 [7a. View of the Deerfield River gorge emerging on valley lowland as seen from Mt. Sugarloaf] 58 [7b. View of the French King gorge as seen from the bridge] 58 [8a. View of Titan’s Piazza at Hockanum showing the columns resting upon the gently inclined sandstone] 60 [8b. View of the Springfield lowland from the Westfield Marble quarry] 60 [9a. The dinosaur track preserve at Smith’s Ferry near Holyoke] 66 [9b. Varved clays or calendar beds on river bank south of Hadley] 66 [10. View of the Deerfield gorge from the east summit of the Mohawk Trail] 92

Figures

Introduction

In every region there is an evening drive which lures the city dweller from the cramped vistas of the office, the home, and the dingy streets to the limitless expanse of hills and valleys, where mental tension relaxes and vision broadens as the physical horizon expands and acquires depth. In less favored localities, the drive may be long and the relaxation short, but not so in the Connecticut Valley. Half an hour of travel, either to the east or to the west from any large community, provides an escape to the hills, where people, cars, houses, and all the minutiae of urban civilization are blurred on the canvas of upland and lowland.

Local pride and personal prejudice may proclaim one view superior to another; but the praise so liberally bestowed upon the heights beyond Westfield, the Mount Tom Reservation, the land called Goshen, Shelburne Summit, and many another site, merely bespeaks the rivalry of equally favored vantage points. Perhaps the trail to Pelham would not be singled out for special mention by the undiscriminating enthusiast, but the connoisseur of New England’s scenic beauty returns and follows it again and again. A good road may take some credit for its popularity, but there is a deeper cause than this which brings him back; for, if there is drama in scenery, he finds it here. The road leads out of Northampton, and from the graceful arch of the Coolidge Memorial Bridge he views the flood-scarred lowlands that border the river, and across the flat plain into Hadley he sees visible reminders that river and farmer periodically struggle over ownership of the land. Then a rise in the road constricts the view but offers a promise of something different. Ahead, rolling fields stretch to the beckoning hills beyond Amherst, but the hills appear and disappear in tantalizing cadence as the car tops each rise and drops into the ensuing hollow. Soon West Pelham comes into view, and the rise to the highland begins. Beside the road a brook tumbles into the valley; and as the car climbs the heights to Pelham, and miles of wooded land are suddenly spread before the eye, the wayfarer realizes that here is the dramatic climax to his trip and to the murmured story of the brook. But the long ridges reaching out to the north and to the south, the deep valleys between them, and the sky which meets the farthest ridge do not enclose the panorama. It has a fourth dimension—time—a dimension as limitless as the horizon.

With just a dash of imagination, the wayfarer may journey backward through time; through scenes of infinite variety; through countless years of unceasing change; through situations so different that he would scarcely have recognized his New England. The scarred plain of the river, the brook, the soil, the rocks, the upland and the valley,—all tell a fascinating and a logical, if surprising, geological tale. A detour down this fourth dimension promises as much interest as a journey through the other three.

Today and Yesterday

From the Coolidge Memorial Bridge the broad lowland seems to reach out in all directions towards the encircling hills. Far down the river, the distant bank rises a sheer thirty feet from the water and is high enough to surmount even the worst of floods. Yet each year this bank recedes as the unconsolidated sediment at its base is sapped by the stream and is carried away. Three times the river road has been moved back from the insatiable Connecticut, and today the main Hockanum highway takes the long route far from the water’s edge.

The River Works

Nearer the bridge the land is lower, and it shows the effects of frequent inundation, but not of scour. A great sand bar lies in the curve of the stream, and the low parallel ridges suggest that they, too, were awash in the Connecticut before its eastern bank encroached so far upon the town of Hadley. The tongue of land which serves as Northampton’s airport is a succession of bars and abandoned channels which record the migration of the river away from its old bank along Bridge Street. The Connecticut is robbing Hadley to pay Northampton, but there was a time when Northampton was pilfered, too.

Swales line the landscape as far as Hadley; and each year, at the time of high water, they must now be content with the meager overflow, where once they sped the entire stream upon its southward course. But even now, in flood, their original function may be restored. For the swale just west of Hadley was a roaring torrent in 1938, 1936, and 1896. Indeed, it threatened to appropriate the entire stream, and each of the great curving hollows that furrow the lowland are scour-channels which were made at other times.

Fig. 1. The Connecticut River undercuts the Hadley bank at Hockanum.

Fig. 2. Natural levees border the Connecticut River south of the Sunderland Bridge.

The river has moved at will from one side of its alluvial plain to the other, and its threats to change its course are not to be taken lightly. Until 1830 it flowed past Northampton, around the great ox-bow to Easthampton and then back to the watergap between Mount Tom and Mount Holyoke. It served as the main line of communication to the Atlantic seaboard and was a much travelled route. In the spring of that year high water breached the narrow neck of land between the two ends of the meander loop, and practically overnight the route to New London was shortened by three miles. Although the event was not a source of rejoicing to the landowners, Northampton declared a day of thanksgiving because they were now, thanks be to Providence, three miles nearer the sea. How often the river has changed its course may never be determined, but the floodplain is grooved with swampy or silt-filled ox-bow lakes, not only near Northampton, but all the way from Brattleboro, Vermont, to Middletown, Connecticut. They tell of older shifts in the course of a river which still displays its brute power within the limits of its alluvial plain.

The inundation of 1936 did more than scour the river’s floodplain; it left thick deposits of sand and silt upon many of the fields. Each preceding flood has done the same sort of thing, dropping coarse sand in greatest abundance on the banks where the river flowed straightest. Flood by flood, the deposit has risen higher on these favored sites, where the swift main current slackens as it spreads over the broad, flat plain. Today the banks form natural levees sloping away from the river at many points southward from the Sunderland Bridge.

Just when the river started to shift back and forth across its alluvial plain is not revealed, but it was long before the white man penetrated the country. Indian graves and campsites have been laid bare as the high water of each new flood has removed the silt left during earlier inundations. The sites rarely yield any implement brought by the Europeans; they record long years of Indian occupation in the land called Norwottock, a land in which the red man found a river which temperamentally shifted its course in response to periodic floods.

The floodplain ends at a rise in the road not far east of Hadley. The rise is a scalloped embankment, reminiscent of the high bank on the river bend downstream from Hadley; even the long narrow swamp at the base looks like a filled ox-bow, and the scallops look like bites which the hungry river took from its banks. This embankment continues northward past Mount Warner, following the present channel closely through North Hadley, and it passes just east of Sunderland village. Corresponding banks are present on the west side of the stream in South Deerfield and Hatfield. Within the confines of those terraces the Connecticut has had free play, but its course has never strayed east or west of these well defined boundaries.

Wave-like hills of sand cap the embankments in several localities north of Hatfield and North Hadley. Some, perched on the terrace edge, were partly cut away when the river was establishing the limits of its floodplain. Wherever the pine trees are cut down, or the grass plowed under, the sand within these hills begins to drift. They look and act like those hills of the desert, the sand dunes, and they record the drift of wind-whipped sand across a naked land, before the river had established a floodplain within its present confines.

The Landscape Changes

Fine sand, silt, or clay is found beneath the windblown sand wherever the river banks undercut the dunes. The clays are especially widespread, for each of the numerous local brickyards has its clay pit, and there are many more clay banks which have no brickyard. The clays are rhythmically banded. One band, composed of very fine material which settles from suspension only after weeks of absolute quiet, retains moisture tenaciously; adjacent bands dry more rapidly, are somewhat sandy, and settle from suspension in less than a week. A large body of quiet water in which so much fine clay could settle must have occupied the valley before the river was there, and the only type of water body which could have provided the proper environment is a fresh-water lake, free from agitation during the long winter months when its surface was frozen over. These thin clay bands are deposits of a winter season, when streams are low and their load light. Then, even the finest particles can settle, during the many weeks of quiet water, as a paper-thin layer upon the lake bottom. The coarser sandy layer just above the finest clay records the spring break-up, the melting of the ice, and resuscitated streams flowing from the hills with a vigor that can be acquired only when the melt-water from the winter snow combines with the normal run-off. The sand which these freshets bring to the lake diminishes as the spring floods subside, and the sediment becomes progressively finer until next spring comes around.

Pl. 2. Features of the landscape which originated during comparatively recent time.

a. Air view of the ox-bow lake between Northampton and Mt. Tom.

b. Roches moutonnées of the Pelham Hills seen from Hadley.

Fig. 3. Block diagram showing the main features of central Massachusetts at the present time.

Fig. 4. Block diagram showing the main features of central Massachusetts during the recession of the Ice Sheet.

Each sandy layer is a spring; each clay band, a winter; and the two together mark the passage of a year. High spring floods are rarely local; floods on the Connecticut are usually matched by floods in the Merrimack watershed to the east and along Housatonic to the west. Floods of the past were much the same, and many of them can be identified readily in the banded clays of the Connecticut Valley. Each one can be traced in contemporaneous deposits which were formed in other parts of the lowland and in neighboring lake basins.

Some of the winter bands, together with the layers below them, are torn and folded, and the tops of the folds have been sheared off. Covering them invariably is the sand layer of the spring break-up. Plain from these features is a winter episode of freezing to the lake bottom, and of ice contorting the clays as it expanded and contracted in response to fluctuations in the surface temperatures. The normal cyclic repetition of sand and clay was resumed when these particularly hard winters came to an end.

At South Hadley Falls the lake clays rest upon a gravel bed, and the bottom layer records the lake’s first year of life in that locality. The overlying bands provide the evidence of a characteristic climatic sequence which can also be recognized in the clays at Chicopee and at other points still farther south in the lowland. But at Chicopee there are many layers which are older than the bottom layer at South Hadley Falls; and at Springfield many layers appear that are older than the basal band at Chicopee. From the sediment deposited in its waters, the story of the lake is not difficult to decipher. It existed at Springfield years before it appeared at South Hadley Falls; in fact, it flooded the meadows near Middletown, Connecticut, for nearly 6,000 years before its waters existed near Northampton.

These beds of clay hold the moisture close to the surface throughout the lowland, making it available to the fields of vegetables and tobacco. Towards the valley margins these crops disappear because the fine sediments end against the rocky shores of the adjacent hills which pass into and beneath sloping terraces of sand and gravel. In the numerous terraces which fringe the hills, the horizontal beds of gravel lie above lakeward-dipping beds of coarse sand; they underlie broad flats furrowed by channel-like depressions which radiate from the valleys at the apex of each flat. On these terraces one can easily picture sand-laden waters coursing through the channels and building deltas outward into the lake.

Deltas were built wherever streams from the highlands entered the valley, and they mark the ancient level of the lake. Strangely, their elevation drops from 315 feet at Montague to 300 feet at Amherst, and is only 268 feet at South Hadley. The changing elevation shows either that the lake surface sloped southward—and indeed this would be unique—or that the shoreline was raised in the north and that the lake drained southward. The latter surmise is plainly the more plausible.

Most deltas on the east side of the valley are pitted by numerous conical depressions. In a depression on a delta plain near Montague, an excavation, made to obtain road fill, disclosed a mass of disordered gravel which must originally have been deposited in the horizontal top-set beds of the delta, but which now lies in the bottom of a depression mingled with the fine sand of the underlying fore-set beds. The top-set beds seem to have been supported for some time and then collapsed as if the underpinnings were removed. The crudely circular or elliptical outlines of the depressions suggest that stray icebergs drifted upon the delta slopes, where they were anchored or buried by the sandy outwash. The buried ice-cakes survived until the lake was drained, and the baselevel of the streams was lowered, for the depressions have no outwash within them. They collapsed soon after the lake vanished, because water soaking through the delta sands melted the ice, much as it thaws the ground for dredging in the Yukon. Even today this gravelly ground, particularly the beach of the ancient lake, is well drained, and it forms the best land for the apple orchards of the valley.

Glaciers Came

The delta deposits and the clays form a thin veneer over a bouldery soil that comes to light along the delta-top margins and in gulches cut down through the gravel and sand. Some of the boulders are huge, attaining diameters of twenty feet; and all are strangers to their present resting places. Some are set upon a bare rock floor, scratched as though by sandpaper, and they teeter to the weight of a child; most are embedded in soil. These “erratics” seem to have been left like unwanted objects, picked up and carried for a time, and then dropped when the bearer wearied of their weight. The scratches on the rock floor are parallel grooves, all of which trend southward. They are unmistakable tracks left by glaciers, and the boulders are like the stones perched on glacial ice for a ride to the terminal moraine.

The land above the old lake shore is bare scratched rock or rocky soil called boulder till. Every hill farm has been cleared of more stones than trees, and it is only with the vogue of the rock garden that these erratics have found any merit in man’s estimation. It has been said with a considerable element of truth that the lake margin can be identified by the stone fences heaped up by exasperated farmers at the line where the water once lapped the slopes of the glaciated hills. Striations and erratics decorate the tops of Mount Tom and Mount Holyoke, and those who visit Mount Monadnock or Mount Washington will find they must inscribe their initials over the signature of the great ice sheet.

The stranger rocks or erratics, stranded promiscuously over the countryside, can be traced to hills farther north. Clearly the ice sheet was moving southward, picking up debris and abrading the countryside like a great sanding machine. Northern slopes were worn to long gentle inclines and the southern slopes kept their original forms or were steepened as the ice plucked fractured blocks from their moorings. One imaginative writer likened the glaciated rock hills to the wigs of sheep’s wool worn by the jurists of his day; the name stuck, and they are still known as roches moutonnées. Look at the Pelham Hills from the Coolidge Memorial Bridge and you will see the top of Jeffrey Lord Amherst’s wig facing towards Canada.

Within the Connecticut Lowland the moving ice often picked up a load of debris more cumbersome than it could drag along. It handled the situation most satisfactorily by dropping the load and streamlining it, and these piles of glacial debris with blunt north slopes and gentle southerly sides are drumlins. When next you pass the apple orchards of South Amherst, recall that the smooth elliptical hill east of the road to South Hadley is a drumlin, a relic of an overloaded glacier.

Just Before the Ice Age

The glacier advanced as far as Long Island and Martha’s Vineyard, and the lakes of the Connecticut Valley formed along the ice margin and spread northward as the ice front receded. The distinct layers, or varves, of clay mark off 25,000 years since the recession began, but for a million years before its final retreat, the ice covered all New England intermittently. This length of time transcends human comprehension unless one considers years in terms of what has been done. A million years is not too long for a sand-laden ice sheet, moving only a few feet each year, to grind tens of feet of solid rock off the north sides of the “everlasting” hills. To those who study the earth, “Before the Ice Age” has about the same significance as “Before the Hurricane” has to the average citizen of New England. It is in such terms that geologic time must be considered.

The ice sheet simply modified the pre-glacial topography; it changed symmetrical hills to asymmetric roches moutonnées and left boulder till spread over much of the bedrock floor. The greatest changes were effected in the White Mountains, where the steep-walled river valleys were changed to troughs with a U cross-section, as in the scenic notches; or with steep headwalls like that in Tuckerman Ravine, a typical alpine cirque. Within the lowlands boulder till was left as a blanket, concealing the irregularities which were made in the rock floor at an earlier geologic date. These irregularities may pass unnoticed unless some construction project happens to reveal them. Bedrock is rarely over seventy feet down at any point in the lowland, but work at the Sunderland Bridge and the Coolidge Memorial Bridge encountered masses of glacial debris in a deep fluvial channel more than three hundred feet below the river surface and at least two hundred feet below the present level of the sea. This deep trough is not over one hundred yards wide, and if it were fully exposed to view, it would look like a miniature Saguenay gorge. Similar trenches in every part of eastern North America, from Hudson Bay to Cape Hatteras, show that the land once stood higher than it does now, and that the main rivers flowed in deep, narrow canyons, although the upland surface between the rivers had its present characteristics. Thus, in Pliocene time, while primitive members of the human race were entering old England, New England rose high above sea level, and its lowlands were trenched by quickened streams.

The narrow gorges are an eloquent, if mute, record of rivers suddenly rejuvenated, their current accelerated and the exuberant waters cutting into freshly elevated rock. Massachusetts and the neighboring states along the Atlantic seaboard formed a plateau-like upland, perhaps one thousand feet higher than today, and the coastline lay fifty to one hundred miles out under the present waters of the Atlantic.

The Pliocene episode of stream incision was of short duration. The gorges are not wide, and only near the sea do they cut deep into the coherent crystalline rock which gives New England its solid foundation. Nowhere did the land remain elevated long enough to permit the rivers to widen their canyons through the plateau-like country and to modify the essential features of the landscape. The latter were acquired in an earlier geologic epoch called the Miocene, and the scenic pattern carved by running water in that relatively remote division of time still dominates the region’s topographic form.

Rivers Carried Off the Everlasting Hills

Every stream has its load of sediment, as the silt- and sand-filled reservoirs along the edges of the valley so effectively testify. Each sandy river bed is an aggregate of rolling grains, moving with the current, slow where it is slow and faster where the current is accelerated, but travelling always towards the sea. Every grain is a piece of the countryside lost to the land and soon to become a part of the ocean floor. Very little of this sand comes from the lowland itself, for the Connecticut may cut the bank below Hadley, but it leaves almost as much sand as it acquires on the opposite shore. The river’s burden is brought to it by swift tributaries—the brook at West Pelham and hundreds more like it. Their sides are cut-banks, but no extensive sand bars are built to balance their erosive work; what they pick up they carry to the lowland, and what they bring to the lowland is soon transported to the sea.

The contribution which the tributaries make to the lowland rivers was demonstrated only too conspicuously by the great fans of coarse debris spread across the valley of the Deerfield River and the West River during the floods that accompanied the torrential rains of the hurricane. Parts of the village of Townshend, Vermont, nestling in the flat floor of the West River valley, were buried in gravel wash, and the hillside roads above were gullied ten feet deep. One harassed traveler aptly remarked that the original road level could be recognized from the few concordant remnants of pavement beside the trout brook.

The hill slopes at Townshend rise and end near Jamaica, about one thousand feet higher in elevation. Here the roads are in good condition. There are no signs of erosion, and the rolling uplands extend for miles with no signs of gullying or wash by the heavy rains.

The debris handled by the West River now and for ages past has come from the steep hill slopes along the main valley. Each load of sand has cut these slopes back from the main stream and has widened the lowland floor. So, for millions of years, the tributaries of the Connecticut have pushed the valley walls farther from the main river, and their tributaries in turn have pushed their hill slopes back, while the valley floors have steadily widened. The Connecticut Lowland was broadened in this way, and the tributary Deerfield has developed its valley in similar fashion but to a lesser degree. Today streams near the headwaters acquire sediment, not from the upland across which they flow to reach the deeply entrenched valleys, but from the steep slopes in the most remote recesses of the upland on which they rise.

Flat valley floors are broadened in coherent rocks as well as in unconsolidated sand—less rapidly, indeed, but just as surely; and every region is worn down to the grade of the streams which drain it, except for those rare masses of resistant rock which defy decay and yield reluctantly to their inevitable fate. The rocks of the Mount Holyoke and Mount Tom ranges, Mount Warner, the Pocumtuck Hills and the highlands on both sides of the Connecticut Valley are made of tougher ingredients than the lowland, and even millions of years of incessant onslaught by running water did not suffice to level them by Miocene time, when the lowland was excavated.

Pl. 3. Erosion remnants or monadnocks surmounting base levelled surfaces.

a. Mt. Sugarloaf, a remnant of Triassic rocks disappearing grain by grain down the Connecticut River.

b. Mt. Monadnock, a hill surmounting the New England peneplain, seen from Mt. Lincoln.

Fig. 5. Block diagram showing the main features of central Massachusetts during the excavation of the lowland.

Fig. 6. Block diagram showing main features of central Massachusetts after the Triassic basins were filled.

The lowland extends beyond our immediate region. It continues southward with diminishing elevation to New Haven, where it joins another broad depression, now flooded by the waters of Long Island Sound.

Before the Rivers Cut the Valleys

Those who would see the land as it was before the rivers carved the lowlands must put back every grain of sand the waters carried away; they must fill in these valleys to the level of the Jamaica upland. Then only will the country be as it was before the streams were rejuvenated and started to cut deep trenches and to widen them as the Deerfield has done at Charlemont.

Broad, open valley flats or straths surmount the steep V-shaped notches of both the Deerfield and Westfield Rivers. Surely, everyone who has paused at the lookout on the east summit of the Mohawk Trail has seen the upland sloping gently towards the Deerfield and then breaking sharply at the top of the present canyon. The same view confronts the motorist who drives from Adams to Cummington, just after he leaves the village of Plainfield. Here the shallow bowl in front of him holds no hint of the deep notch in which the Westfield flows. The gentle contour of the land suggests only the slow but methodical sort of change which comes with maturity. Those who favor air travel will see, as they fly over Mount Tom, a similar but more dissected strath reaching into the hills northwestward from Northampton. Aeroplanes flying the Boston-New York route pass over straths which have been trenched by the Connecticut along its course from Middletown to New London.

The straths are part of a mature, but ancient drainage system, which was graded a thousand feet above the level of the present streams and only a few hundred feet below the main upland. Certain broad depressions through the highlands east of the Connecticut Lowland suggest that this drainage pursued a southeastward course to the Atlantic, and that the river did not establish its modern course until the straths were elevated and notched.

The land level above the strath-margins is a still older surface from which the rock-benches were cut. The higher surface stretches to the horizon at Pelham, but Mount Monadnock and Wachusett stand conspicuously above it. And on the Mohawk Trail one must ascend the tower at the eastern summit before any higher land comes into view. Greylock’s summit and the long chain of the Green Mountains attain greater elevations. The West River and Deerfield basins are graded to the level of this higher and older erosion surface, but farther north a chain of peaks including Stratton and Okemo swing eastward towards Ascutney. They appear to have formed a divide on this ancient land, as they do today; and beyond their crests rivers have run to the Saint Lawrence and Hudson basins from a time which antedated any of the familiar features of the New England landscape.

Although this flat upland surface is more complex than it appears to the eye, it dominates all of southern New England, and ramifying arms of it penetrate northward into the White Mountains of New Hampshire and Maine. Another great arm passes west of Mount Greylock and spreads out between the Catskill Mountains and the Adirondacks. During the long period of erosion when it was formed, New England was reduced nearer to the grade of the main rivers than at any other time either before or since, and only rocks which have effectively resisted all later assaults by the geologic processes of destruction surmount the surface. To the eye, the region appears so nearly planed that it has been called the New England peneplane.

The upland continues southward through the Berkshire and Litchfield Hills, descending in a series of almost imperceptible steps towards Long Island Sound and the Atlantic. A few miles south of Litchfield, Connecticut, its low angle of declivity increases abruptly, and the more steeply inclined surface passes beneath the waters of Long Island Sound. The sudden change in dip suggests that two erosional planes are present and that each was formed under somewhat different circumstances and in different periods of geologic time. The soundness of this surmise can be demonstrated in Long Island where sediments laid in a Cretaceous sea rest upon the older and more sharply inclined erosional plane and rise approximately to the level of the New England upland. The deposits form a wedge between the two planes, and their Cretaceous age supplies a series of dates that would otherwise be difficult to establish in New England’s geological history. Erosion fashioned the New England upland in the early and middle epochs of the Tertiary period, immediately following the deposition of sediments in the Cretaceous sea. And the southward sloping plane upon which those sediments rest records an even earlier episode of denudation—an episode lost in the shuffle of later events in Massachusetts but preserved in fragmentary form in Connecticut, thanks to the protection afforded by the sedimentary cover.

Had we lived in central New England when erosion of the upland and of the younger straths was in progress, we would have noted that the valley forms were well defined in the headwaters and lower reaches of the streams, which made their way through a country of light-colored or gray clayey soil. In the middle reaches the valley boundaries were blurred and indistinct, and the country through which they flowed was surfaced by red and sandy soil. The middle region is now the lowland, but even then it formed a depression athwart the topographic and hydrographic features of the country; and its distinctive red soil resembled alluvial wash or fill in a long basin. Its low relief would have been as impressive in early Tertiary time as its higher relief is today, for then it had little topographic competition anywhere between the present sites of New Haven, Connecticut, and Northfield, Massachusetts.

The land had one dominant characteristic—a relatively flat or faintly terraced surface. But this surface concealed a mosaic made of an infinite variety of rocks, each responding to the attack of weather in its own particular way. Erosion has brought out the pattern of the mosaic, and we have retraced the steps in its development. Viewing the evolution of the countryside in retrospect, we see its features take form much as a worker on an inlaid bronze might watch the design come out when it is etched. The creation of the mosaic or inlay is another part of the history, and the relief of the land now permits closer scrutiny of the pattern than would have been possible in Cretaceous time.

The Mosaic of Central Massachusetts

The great artisan incorporated three main features in the mosaic beneath the New England upland, and from them erosion developed the major pattern of the present landscape. The three units of the pattern comprise a somewhat heterogeneous but durable foreground in the east, a weak inlaid design in the center, and a moderately homogeneous and durable background in the west. The foreground and background are simply a suitable base for the younger, central feature of the design—an inlay which was completed in Triassic time, while the mighty dinosaurs were beginning to gain confidence as the new rulers of the earth. Skillful artistry and complicated technique were expended on the Triassic inlay, for in part it was rolled in, partly melted in, and some of it was cut in amid the tougher materials now found on either side.

The Red Rock Basin

The youngest ingredients which were incorporated in the inlay are a series of fine-grained red sandstones and consolidated clays or shales. They are horizontal layers, turned up slightly at the edges of the lowland, but elsewhere they lie in almost horizontal beds that extend from South Hadley through Chicopee (Chicopee shale), Springfield, and Longmeadow (Longmeadow sandstone) to a point just south of Hartford. Near the hills which form the eastern boundary of the lowland these fine-grained sediments locally give way to coarse tabular deposits of angular gravel, which appear along the base of the Wilbraham Mountains and again in Mount Toby and northward. The deposits are isolated or detached masses which resemble fans emerging from mountains, not unlike the more modern sands and gravels which the Westfield River left where it emerged from the western hills. But the Triassic gravels are red, and they are firmly cemented into conglomerate; yet it is plain that this part of the inlay was made by washing and rolling the red muds, sands, and cobbles into a depressed basin waiting to receive them.

The southern part of the basin was deepened, and the highlands were rejuvenated spasmodically from Springfield to New Haven. The sinking of the lowland on the west and the rising of the highlands on the east took place along a fracture plane, commonly called “the eastern border fault,” near the eastern limits of the red sediments throughout that part of the valley. The rocks composing the alluvial fans are flexed sharply downward east of Portland, Connecticut, like compressed pages in a book, where the great eastern mountain block pushed obliquely against them. In this way the mountain range was renewed as erosion wore it away, and the basin was deepened periodically as the wash from the highlands filled it. The intermittent uplift sustained the growth of the fans along the edge of the lowland, but the frequent recurrence of movement never permitted these graded accumulations of waste to extend far out from their mountain sources.

The great fracture, which sharply delimits rocks of different origins, and the deformation in the strata near Portland record, as surely as the writings of any human historian, a tale of periodic rock compression and paroxysmal release that must have been accompanied by violent tremors. Connecticut and Massachusetts had their earthquakes and had them as violent as any now originating in the western ranges of the United States and Mexico; but happily they shook a land which was overrun by the dinosaurs, and which was not yet ready for human habitation.

Fig. 7. Map of Mount Toby showing gorges filled with conglomerate.

Near the northern terminus of the Triassic basin the eastern boundary was not subject to intermittent and violent movements during the later stages of sedimentation, as it was in the south. Instead, the youngest part of the red-rock inlay consists, in some places, of unfractured boulder beds which were washed far out towards the center of the lowland; elsewhere, landslides brought masses of rock debris upon soft red and gray shales, which may have accumulated in shallow lakes; in still other localities, long stringers of red sediment reach far back into the eastern highlands. Many boulders in the conglomerate at the south end of Mount Toby are eight feet in diameter, and torrential mountain streams brought them to their resting place. A few are scratched and grooved, much like the boulders in the till left by the ice sheet; perhaps they signify the presence of snow fields and glaciers in the mountain range, but the scratches may have been acquired by avalanching. The landslide masses buried in the shales at the Sunderland caves show that the mountain front was steep, and the ancient talus or slide rock near the Central Vermont Railroad south of Roaring Brook shows plainly that the mountain front was a precipitous cliff of granite. The stringers of conglomerate extending eastward into the granite upland south of Montague, north of Leverett station, at Amherst, and again near Granby, are alluvial fill in ancient mountain gorges.

This old mountain mass stood out as a long, straight range extending from a point east of New Haven northward into New Hampshire. It was of moderate height in Connecticut, but it became higher and more rugged to the north; glaciers may have nestled around its crest east of Deerfield, and its front was an impressive slope of slide rock. Granite gorges with tapering gravel plains, dry one day and raging torrents the next, fingered eastward into the mountain block. At that time the Connecticut Valley was much like the land east of the Sierra Nevada in California, where greater contrasts in heights and depths are to be found than in any other part of the United States.

A Dinosaur Diary

Like the valley east of the Sierras, the depression in central Massachusetts contained playa lakes and intermittent streams. Sand brought by the mountain torrents clogged the channels and spread into broad alluvial plains, while silt accumulated in muddy lake basins. Black sandy shales now mark the sites of the lake beds, and their black color comes from the coaly remnants of Triassic plants. Some swampy lake margins supported peat bogs, which have been preserved in coal seams two to three inches thick between Granby and South Hadley. Many of the lakes lasted long enough to become stocked with half a dozen species of fish. But the fish led a precarious existence, and their skeletons were buried in great numbers in the upper lacustrine layers when the lakes dried up, and dust and sand drifted over the parched basins at Durham, Connecticut, and at Sunderland, Massachusetts. The remains were interred even more effectively when cloudbursts in the hills brought thick layers of gravel out over the ancient lake beds.

Most of the lakes and ponds were ephemeral, but the fact that their presence was more than a mirage in a Triassic desert is clear from the ripple-marks retained on their sun-hardened surfaces, and from the impressions of objects which touched them while they were still soft. Stray series of parallel furrows record the passing of drifting shrubs, and the abrupt disappearance of rain-drop imprints at a well defined line in the hardened mud marks the exact position of the water level in a few of these Triassic water bodies. Footprints register the activities carried on by a bizarre animal population. Beside the road to the French King Bridge and in the river bed at Turners Falls the ripple-marked surfaces contain the impressions of many feet, and the dinosaur tracks at “the Riffles” beside the Northampton-Holyoke highway are known throughout the country. In Connecticut, Middletown and Durham are famed for their tracks, and the impressions left in the playa beds by muddy feet are so widely distributed throughout the lowland that it must have taken a lot of walking by many generations of dinosaurs to leave such an ample record.

Pl. 4. Rocks of the Triassic basin and their record.

a. A dinosaur walked from the raindrop marked surface at the right to a shallow pond at the left.

b. Volcanoes ejected much ash and many bombs to form the Granby tuff.

Some of these three-toed animals were like the modern lizards and walked on all four feet; but the great majority walked on two feet and, like the kangaroos, used their tails to balance their bodies, and their short fore limbs to support them when they crouched. In any single playa deposit, variations in the sizes and kinds of footprints reveal that many individuals made them; yet strangely, most of the tracks at any one place are headed in a single direction. Apparently the herd instinct must have been strong in these reptiles, as it is in kangaroos or in a flock of turkeys, all following a leader, with only an occasional individual going off to one side or back-tracking in a display of independence. And so the dinosaurs dominated the life in the early Connecticut basin, as it sank and trembled, and as mountains rose to the east; on dry days and days of cloudburst, on hot days and days when frost crystals formed in the mud, they roamed the plain, as the lowland settled nearly two miles and filled to the brim with red sands, muds, and marginal gravels.

Volcanoes

Red is the predominant color in the central inlay of the New England design, but greens and blue-black lines have been worked into the pattern. The dinosaur-ridden basin has a rim south of Middletown in Connecticut, and another north of Holyoke in Massachusetts; it lies just west of the dinosaur-track ledge near Holyoke, and the tracks themselves are only thirty feet above the bottom of the basin. The rim is an odd ensemble—now red and now green; here solid and hard and black, there soft and fragmental and crumbly. The fragments may be angular or round; sandy or glassy; dense and solid, or full of bubble holes like molasses taffy. The whole looks like the spread-out ash dump from a giant power plant. And not only does it resemble an ash heap—it is the ash heap of a volcano; and the hard black layers within it are lava flows interspersed with the heavy falls of ash.

Fig. 8. Map showing agglomerate burying a fault scarp on the power line through the east gap of the Notch.

The ancient ash heap grows thicker east of the Connecticut River, and it is more than 3,000 feet from top to bottom around a series of massive blue-black rock-columns southeast of the Mount Holyoke Hotel. These are the lava-filled necks of craters which became quiescent with the dawn of the dinosaur days. The ash deposit, called the Granby tuff, grows thinner eastward away from the craters and disappears completely northeast of Granby, where a stream deploying from a valley in the eastern mountains washed it away as fast as it fell and left coarse gravel in the form of a huge fan.

The floor on which the ash came to rest was not everywhere the same. Where now it crosses the Northampton-Holyoke highway and the Amherst-South Hadley road it was a lava flow; but north of Granby and at numerous places between the Hockanum and Amherst-South Hadley roads the ash lies on conglomerate. Along the Amherst-Springfield power line, a block of the conglomerate floor was pushed up five hundred feet above the same beds farther west, forming a small block mountain which was entirely buried beneath the ash. Similar block mountains can be observed under the blanket of ash, especially on the south side of the Holyoke Range; and renewed movement subsequently affected many of the blocks north of Granby, where the ash deposit and even some of the sediments laid down in the earlier days of the dinosaurs were fractured and displaced. As a rule, along any one fault, the block on the east was pushed up and moved southward; and the block on the west was pressed down: as a group, the fractures may form the beginning of the great eastern border fault which bounds the basin farther south.

The volcanoes which made the Granby tuff or ash bed erupted intermittently for a long period of time. Usually, the river which emerged from the eastern mountain range brought so much fluvial debris that ash is not in evidence except in the immediate vicinity of the craters located between the Notch and the summit of Mount Holyoke. Even though alluvial sands and gravels supplant the tuff here and there, the river did not succeed in closing or quenching those fiery vents. The rocks now present recount a struggle in which, at times, the river encroached upon the cinder cones; at others, the ashes choked the stream and buried its alluvial wash.

While the volcanoes rumbled and erupted, earth forces intermittently thrust the eastern mountain range southward and upward, dragging the eastern margin of the lowland with it and upturning the sedimentary fill, much as a plow might upend a layer of snow at the roadside before shearing it off and pushing it out of the way. The relentless movement caused the entire eastern floor of the basin to be broken into blocks; the easterly ones were piled against the westerly, and their eastern edges were pushed down into the basin floor and the western borders rode up on their neighbors. Through all this tremendous disturbance the great stream pouring out of the mountain pass kept the elevated blocks cut down and the small basins filled in. Earthquakes, erupting volcanoes, and shifting rivers made life for the dinosaurs troubled and a bit uncertain.

Only once did the volcanoes dominate the situation in the valley, and that was very early in their history. A group of vents, localized along a southward trending zone about a mile west of the Notch, and another group along the present course of the Connecticut River from Turners Falls to Sunderland poured out billions of cubic feet of black basaltic lava into the center of the lowland. Eruptions followed in such rapid succession that the rivers never scoured the surface of the earlier flows. Lava piled up 400 feet thick in the center of the basin east of the Mount Tom Range; it moved eastward in a flow which thinned against the fans of rivers issuing from the eastern mountain, and it ended in a formidable wall of scoria confronting the mountain streams. Lava buried the northern basin from Sunderland to Turners Falls and beyond, while the southern basin filled from Northampton to New Haven. But lava dominance was short-lived, and even before its bubbly surface reddened to the weather, streams had covered it with gravel.

The lava flows are the most resistant materials used in the lowland design. They form the ridge east of Greenfield in the northern basin. The Holyoke and Mount Tom Ranges are remnants of these flows, tilted at moderate but varying angles by the recurrent movements which enlivened the epoch of dinosaurs and volcanoes.

Fig. 9. Block diagram showing the main features of central Massachusetts during volcanic stage.

Fig. 10. Block diagram showing the Triassic basins of central Massachusetts.

The most spectacular episode of lava extrusion was localized in a small volcanic center situated about one mile west of the Notch in the Holyoke Range. All flows in the range moved away from this center, and before the great outpouring took place, minor explosive outbursts had built cones of ash with bases up to a mile in diameter. Small lava tongues are interspersed with the ash beds, and mixtures of sand and lava tell of breaks through the 1,500 feet of sandy fill which was rapidly accumulating in the basin. Throughout this early period of volcanic activity the streams brought out so much wash from the eastern mountains that they soon dominated the scene in Massachusetts, and in Connecticut volcanoes gained ascendancy for one brief moment of geologic time, when an early flow covered much of the valley from Hartford south.

The Original Valley

The first and oldest ingredients in the central design are entirely red. The materials are fragments of older rocks—granite and gneiss, schist and pegmatite, feldspar and quartz. They are invariably coarse, for every layer of inwashed sediment has pieces over an eighth of an inch in diameter, and only the coarser particles were smoothed. The finer particles were not moved about enough to have their sharp corners worn away. The pebbles and clay in the thick layers of conglomerate at the French King Bridge were dropped by rushing, overloaded torrents deploying on a lowland—a situation not unlike the one at Townshend, Vermont, during the hurricane deluge. Only fine debris was transported across the fans to the far side of the basin. The western hills made small contributions of sediment; but their streams brought particles which never exceeded an inch in diameter, and in quantities so moderate that the fragments underwent some sorting and sizing as they were spread over the lowland. From the very start the valley was deeper near the east wall than the west; and the eastern mountain block was greatly elevated, whereas the western block was simply a hilly upland.

Fig. 11. Map of the old volcanic region near Mount Hitchcock and west of the Notch.

The edge of the eastern mountain mass is located at the French King Bridge and passes half a mile west of Montague. Its location beneath the younger fill is known less perfectly farther south, but it seems to extend through Amherst, certainly west of South Amherst and Granby and probably east of the Notch. At least two mountains rose above the ancient lowland floor; the northern one is a long ridge of schist between Bernardston and Mount Hermon, and the other is Mount Warner. Mount Warner is an island of highland rocks in a sea of red sandstone fill. The Bernardston ridge resembles a peninsula in somewhat analogous sedimentary surroundings. The two eminences reveal the form of the valley floor and the western hills at the dawn of the Triassic period, for they were spared from destruction by burial, until deep erosion exposed them again in Miocene time.

Hot Springs in Central Massachusetts

Hot springs the world over register their presence by leaving deposits of unusual minerals, and they have left this sort of record at Loudville. Here the coarse sandstones of the lowland rest upon gneiss, and at the south end of the Loudville lead vein barium sulphate crystals, called barite, formed in the sand before it was cemented into solid rock. The crystals are the product of highly charged mineral water, rising through the sands from a subjacent fissure. The fissure itself is also filled with barite, and with galena and quartz as well. It is the vein which was worked in the old Loudville lead mine. There are other veins in the western and eastern highlands at Hatfield, at the Northampton reservoir near Whately, and at Leverett. All are in fractures which were still partly open when the valley first took form.

The Marginal Uplands

The rocks which formed the high eastern mountain range of Triassic time and the rocks which made the old western hills and underlay the basin floor comprise essentially a single group characterized by its complexity. At one place the rock resembles sandstone, but the layers stand on end; at another, it looks like shale, but the stone breaks across the color banding instead of parallel to it; and at a third place a fissure seems to have opened and had a crystallizing melt poured into it. These tabular, filled fissures can be found nearly everywhere, coursing in every direction and at all conceivable inclinations to form a network that binds the older rocks into a firmly knit whole. The fillings, or dikes, are like reinforcing rods, holding the rocks together and withstanding the agents of destruction. Thus, the story of the highlands has three distinctive phases,—a relatively young phase when the interlacing reinforcements were poured into fractures; a somewhat more remote stage, when the bedded rocks were crumpled into their inclined positions; and an earlier stage, when the bedded rocks were deposited. The geologic dates of these three events may vary from one locality to another, and they certainly are different in the Eastern Upland as compared with the Western Upland; but the events always occurred in this sequence and constitute the broader aspects of the story at all places.

Fig. 12. Block diagram showing topography during formation of the lead veins.

The Eastern Upland

The Eastern Upland includes the land between the Connecticut Valley and the Atlantic Ocean. At present, it has the general form of a broad rolling highland with ridges and valleys that have a north-south trend. Close inspection shows that the rocks in the ridges are different from those in the long valleys. Also the layering of the materials ranges from a vertical attitude, as at Ware and Brimfield, to undulating and almost horizontal positions, as at Spencer and Worcester.

Through vertical and horizontal beds alike run those reinforcing sheets—some tabular and vertical, called dikes; others also tabular but horizontal, called sills; and some are just huge, irregular masses without visible bottoms, called stocks and batholiths. Some of them, composed of uniform, small, light-colored minerals, are granite; others are made entirely of large minerals over an inch across and are called pegmatite; a few, with cuneiform intergrowths of a dark mineral in a light one, arranged like Arabic writing, are known as graphic granite.

Pl. 5. Intrusive and extrusive igneous rocks.

a. Columnar lava rests upon red sandstone in the cliffs at Greenfield.

b. Fissures were filled with liquid rock that became solid and bonded wall to wall at the Windsor Dam.

Every one of these masses flowed into the rocks along fractures and other zones of weakness, crystallizing as they lost their heat and solvents to the hot springs of that ancient time. They are all invaders, or intrusives, which inserted themselves into the older beds. Whether they were squeezed into the fissures by the pressures that crumpled the original beds into their upturned positions, or whether they, like the liquid in a hydraulic press, transferred pressure from a deep reservoir to the walls of the fissures and so pushed the beds into their distorted forms, is unknown. Two features are clear; the distortion of the beds and intrusion of the liquid bodies were almost simultaneous, and the hot springs associated with them were still active at the dawn of Triassic time. These profound disturbances transformed the land into a series of elevated, wave-like folds, and rains promptly began to tear away at the summits of the newly raised mountains. From them was carved a serrate and rugged landscape, part of which was later buried beneath the Triassic fill.

Coal Swamps in Massachusetts and Rhode Island

Among the strata of the Eastern Upland which were folded, intruded, baked hard, and stewed in hot spring water, one group stands pre-eminent. It forms a broad band starting north of Worcester and reaching to Providence and beyond. Nearly everywhere it carries coaly material or impressions of plants which are now extinct, but which flourished in the Coal Age or Carboniferous period. Some of the coal seams were mined in the Providence basin, but they had been so heated by intrusive granite that they are partly graphitic and proved difficult to burn. The great extent of some of the coal seams suggests a panorama of immense swamps, and of land so flat that, for long periods, streams brought no sediment, and the trees and water-loving plants furnished the only fill. At other times sluggish rivers, flowing from the northwest, laid thick layers of sandy mud over the surface of the bogs. The alternating muds and coal seams are thousands of feet thick, and they record the story of a basin which sank as fast as it filled—a depression which was never built high enough to be a well drained plain, yet never subsided sufficiently to be inundated by the sea. The Carboniferous peat bogs and mud flats may have extended westward almost to the Connecticut Valley; and farther to the northwest they were bounded by a chain of rolling hills.

The rock floor of the coal basin contains a variety of ancient materials. Some rocks were river deposits, some were marine limestones, a few were lava and volcanic ash, and many were granite and gneiss which crystallized at great depths and became exposed only after streams had stripped away the thick overburden. The basin floor thus holds a complex story, in which land and sea, vulcanism and quiet, erosion and deposition, all played their respective roles. Only in the west, along the margin of the Connecticut Valley, is the involved story at all clear. And in the Western Upland across the red-rock inlay, it is possible to see some of the land as it was before trees took root in the swamps, and rivers brought sands and muds from the vegetated hills that hemmed in the coal basin.

The Western Upland

Many years ago, when transportation facilities were not what they are now, New England settlers mined iron ore from the hill north of Bernardston and smelted it in local charcoal furnaces. The rocks containing the iron are creased into sharp, close folds, and they came into such close contact with a hot granite intrusive that their minerals were changed by its action. This granite, however, is older than the one which is associated with the disturbed Carboniferous beds, for it was intruded when the Devonian sediments from Gaspé to Connecticut were deformed. It was this profound disturbance that turned the red rocks of Roche Percé from a horizontal to a vertical position and raised a mountain range which stretched through all of northern New Brunswick, Maine, the lowland section of New Hampshire, and a belt extending for some miles east and west of the Connecticut Valley. The eroded remnants of these Shickshock Mountains formed the backdrop for the great Carboniferous coal swamps in Rhode Island, Massachusetts, and Acadia.

The iron ore was a hot spring replacement of a limestone containing shells of sea organisms which lived when chordate animals first became abundant. This was the Devonian period in geologic history—the time when a backbone appeared essential in every really high-grade animal. The limestone rests upon a beach gravel, now consolidated into a quartzite conglomerate. The gravel consisted of small white quartz pebbles which came from the many veins in the steeply inclined slates of the adjacent coast.

Marine deposits of Devonian age are found as far south as Leverett, and scattered outcrops indicate that the old seaway reached northward up the Connecticut, entering Canada east of Lake Memphremagog. Thence it spread eastward to Gaspé and westward to Montreal, and around the north and west side of the Adirondack Mountains into New York State. A low rolling land where the Green Mountains stand today formed the western shore of the Devonian sea for many miles northward into Quebec. The Adirondack and Taconic Mountains were a fused aggregate of undulating uplands which limited the seaway on the south along the International Boundary. Its eastern shore lay far beyond the horizon of the region described in this brief account.

The rocks of the old Devonian coast in Massachusetts were chiefly slates, cut by many quartz veins. They are exposed along the Mohawk Trail in the ascent from Greenfield to Shelburne Summit, and they continue northward in an almost unbroken band through Bernardston, Brattleboro, and Northfield (Vermont) to Lake Memphremagog. They contain casts of planktonic life which inhabited the Ordovician seas in these northern latitudes, and the Ordovician strata, together with still older Cambrian sediments found below them, meet the Devonian beach deposits at a sharp angle, just as the slates along the coast of Maine meet the modern beach sands and gravels. Like the slates of Maine, they were eroded deeply before the beach existed, and their slaty structure and their steeply inclined attitudes were acquired in a still more ancient epoch of deformation.

The folded rocks of Ordovician age flanked the highland area which now constitutes the axis of the Green Mountains. West of the Green Mountains they make the Taconic Range, and to the east they appear in ranges that go under a variety of names, including the Northfield and the Lowell Mountains. In the Taconics the folds have the shape of waves advancing westward from the center of disturbance in the Green Mountain axis; within the Connecticut basin the Ordovician folds have wave-fronts which advance from the same axis eastward across the Memphremagog sea. Along the eastern margin of the old land a series of dark green intrusives called peridotite welled up from the depths of the earth, and they now cut through the rocks extending from Chester, Massachusetts, to Thetford Mines, Quebec; they are like giant boundary posts marking the ancient line of demarcation between sea and land in Cambro-Ordovician time.

Originally the folded strata in the Taconic region were deposited in clear marine waters, where calcium carbonate accumulated rapidly. But the sediments of the same age east of the Green Mountain land represent an unbroken succession of hardened muds, which rest on sandy muds, and on fine and coarse products of violent volcanic eruptions—tuffs and agglomerates—and lava flows. No lime-secreting animals could thrive in this sea, although they numbered billions in the western waters; for only floating plankton could escape the interminable mud, and they drifted up and down the coast from Quebec to Connecticut. One or two straits may have connected the clear waters of the west with the muddy waters of the east, for some of the planktonic organisms have been found in the muddier sediments of the westerly waterbody.

The Cambro-Ordovician sea lapped even older rocks, contorted and cut by intrusives which bonded them precisely as much younger invading liquid rock bonded the younger sediments of the Eastern and Western Uplands. The older rocks were also laid in a sea—a sea so much more ancient than the Cambrian and Ordovician seaways that its shoreline and even its form and extent are at best conjectural. And when we study these oldest marine beds, we find that their ingredients were in part derived from still more ancient sedimentary rocks, which accumulated in the sea, and that these old beds were elevated into the land that supplied the waste now found in the oldest coherent section of rocks in western New England. Indeed, the dawn of the Cambrian period, when life first became abundant, was merely a half-way mark through geologic time. Although half a billion years have elapsed from the Cambrian to the present, another half a billion years reach still farther back towards the beginnings of earth history, beyond which science has not yet peered successfully. These billion years are but a finite segment of history, bounded by the infinite past and the infinity of the future.

It seems appropriate, therefore, to end our journey down the fourth dimension at this point, and as we retrace our steps, we can profitably survey the chronologic succession of events and scenes which followed each other from Cambrian time to the Twentieth Century A.D.

The Story of Central Massachusetts

The protracted story of central Massachusetts might be that of many another section of eastern North America, except for minor details. In Cambrian time an inland sea, well stocked with simple marine organisms, washed the shores of an archipelago which extended north and south through the Berkshire Hills, the Green Mountains, and the Notre Dame Mountains. Composed of rocks which themselves had had a long and involved geological past, the islands rose intermittently as streams and waves wore them away. Clear water and sandy beaches stretched along their western shore, and the original Adirondack Mountains were just visible from the summits of the higher islands. Swift streams raced down their eastern slopes, carrying gravels, sands, and silts into the eastern arm of the sea, and only free-swimming animals could survive in its turbid waters. For a time, volcanoes erupted and fumed along the entire eastern coast from Thetford Mines, Quebec, to Plainfield, Massachusetts, but their activity was short-lived. Only the streams which drained the broad islands endured, and they never ceased to pour mud into the eastern ocean. Gaps in the island chain permitted some of the free-swimming organisms to migrate to the western sea, where bottom-living plants and animals were actively secreting the limy shells and skeletons which helped build thick deposits of Cambrian limestone.

These conditions continued into the ensuing Ordovician period of geologic time, but gradually the situation changed. Again the volcanoes renewed their activity, and masses of dark peridotite were intruded along the eastern shore; the island chain rose rapidly, and the straits closed. The elevated land began to expand outward, and folds spread eastward on the east and westward on the west, like waves from a center of disturbance. So great was the pressure that portions of the old land were sheared outward over the folded sediments. The Taconic disturbance was on from the city of Quebec to the city of Washington; and the streams, like ants, kept at their endless task of carrying sand and gravel into any and every depression they could find. They piled up great thicknesses of Silurian sandstone in Maine and New York, and so effectively did they tear down the Taconic Mountains that the Silurian sea was ultimately able to penetrate the region from Thetford Mines, Quebec, almost to White River Junction on the Connecticut River.

Fig. 13. Block diagram showing main features of central New England during middle Ordovician time.

Fig. 14. Block diagram showing main features of central New England at the end of Ordovician time.

Fig. 15. Block diagram showing main features of central New England during the Devonian period.

One period later a Devonian sea followed in the wake of the Silurian sea, but its waters penetrated even farther south to Leverett, Massachusetts. The quartz gravels of its advancing beach covered the worn flanks of the Taconic folds. Sea animals left their shells to form a bed of limestone which may be seen today at Bernardston. But again the sea was shouldered aside by the restive land, which rose from Gaspé to Virginia. Much of the region affected by the Taconic disturbance was elevated again, and a broad band of Devonian sediments was folded closely through northern New Brunswick, southern Quebec, northern Maine, northern and central New Hampshire, and central Massachusetts. Granites welled up into the sediments, and dikes filled all the fissures. The baking, stewing, and reinforcing they gave to the older sediments made them so firm that they are still one of the most coherent and resistant series of rocks in New England and maritime Canada. This was the Shickshock or Acadian disturbance. Meanwhile the first forests took root on the long piedmont plains that spread from the rising mountains westward into the Catskill Plateau of New York State (Catskill sandstone) and eastward to the coast of Maine (Perry formation).

The margins of the piedmont plain sank. Vast, luxuriant swamps succeeded the old forests in Pennsylvania on the western piedmont, and in Rhode Island, Massachusetts, and Acadia on the eastern piedmont. The swamp vegetation later became the coal seams of eastern North America, and well does this time merit its name—the Carboniferous period. The Shickshock Mountains remained in the hinterland forming highlands from Spencer, Massachusetts, westward into New York State; but they were shorn of their crags, and only on rare occasions were the streams swift enough to carry silt into the swamps and to bury the accumulated peat.

Fig. 16. Block diagram showing the main features of central New England during the Carboniferous period.

Fig. 17. Block diagram showing the main features of central New England in early Triassic time.

Fig. 18. Block diagram showing the main features of central New England during late Triassic time.

Torn and twisted as New England had been by the two previous disturbances, it was to suffer yet again. The entire northern section of the eastern coal swamps began to rise, and the movement spread southward through New Jersey, eastern Pennsylvania, Maryland, Virginia, the Carolinas, and Georgia. Granites insinuated themselves once more into fissures in the elevated landmass; the rocks were pushed outward from the raised block; and the sediments of the coal fields were thrown into folds which diminished in magnitude towards Ohio on one side and Cape Breton Island on the other. This was the Appalachian Revolution. When it was over, even the youngest sediments were interlaced with granite sheets and dikes; they were cooked hard in hot spring waters; and they were crumpled into close, long north-south folds. The landscape was changed completely: mountains had replaced the peat swamps; and from their summits alpine glaciers were plucking rock fragments which they dumped into the Boston basin. Streams, too, cut deeply into the mountainous upland, but there were no other local basins in which the fluvial debris could come to rest.

This was, in brief, the course of events which transpired in that era of geologic time called the Paleozoic. Twice as long as all ensuing time, the era was one of kaleidoscopic change, with placid seas, eruptive volcanoes, swift streams, and towering mountains competing for the lead roles in three rather similar historical cycles. When the Paleozoic era was over, the matrix of tough, resistant rocks was ready for the delicate inlaid design which was imposed upon it in the Triassic period.

There was nothing tranquil about Triassic time. While hot springs, born in the cooling granites, still oozed from rents in the mountainsides, a tremendous 100-mile-long rift tore through the east margin of the old Shickshock Mountain foundation. The rift was a clean break at some places, but elsewhere it was splintered and offset. Each northern sector of the break invariably ended west of the beginning of a southern one, and the intervening rock is characterized by multiple fissures with more or less displacement of their walls.

The block east of the rift moved south and rose, while that to the west was depressed into a tilted and asymmetric basin. Mountain streams flowing eastward to the Atlantic were caught at the base of the rift, and a new set of torrents dashed down the west-facing scarp of the elevated block. After every cloudburst these new streams left their contributions of boulders in screes along the east side of the basin. The gravels steadily increased in thickness, covering the hills and valleys that furrowed the lowland floor. Much of the ancient relief still lies buried beneath the fill, but some of the eminences were exhumed one hundred and fifty million years later and have received man-given names like Mount Warner and Bernardston Ridge. As the basin subsided vertically for more than a mile, the mountain streams spread fans westward across most of its floor, restricting the contributions of the western rivers to a zone which is now less than two miles wide. The largest of the eastern rivers wore a valley three miles wide where it entered the lowland northeast of Granby.

Then volcanoes broke loose in the basin floor. Lava oozed through the sand west of the Notch in the Holyoke Range, and it frothed out of the openings or was blown violently from them. But by sheer persistence the rivers still dominated the scene as volcanic activity waxed and waned, and 1,500 feet of alluvial wash piled up around the volcanic cones. The energy of the volcanoes was ultimately spent, but for some time lava poured out of craters along a line extending southward from the main eruptive center, and from a second center which approximates the course of the Connecticut River from Sunderland to Turners Falls. It flowed westward into the middle of the basin in a series of sheets until it was 400 feet deep; it pressed upward against the sand plains along the western hills; it surged east up the fan slopes where it ended in a frothy wall; and it spread southward from these two centers and from others to New Haven. The lava, now tilted, gives substance to the Greenfield Ridge, the Mount Holyoke and Mount Tom Ranges, and the long line of hills that pass through Hartford and Meriden.

Spectacular was this outburst in its time, and profound was its influence upon later scenery, but short was its duration. Before weather could redden the lava surface, streams washed gravel over it; and only at the main centers between the Mount Holyoke Hotel and the Amherst-South Hadley road were the volcanoes able to hold out against the relentless activity of running water.

The block east of the rift continued to move southward and to rise, while the streams draining it entrenched themselves in an effort to remain at grade with the basin floor. The moving mountain mass pushed the lava flow up on end and twisted its eastern edge around, dragging it along to the south. The rock splinters which were formed in the process sliced the basin sediments into small blocks, some of which can be seen north of Turners Falls and also at the Holyoke Range. Ultimately the upward and southwestward movement along the rift piled the eastern blocks against the more westerly ones, pushing the west side of each eastern block up on the east side of the adjacent western one, and depressing its eastern side more deeply into the basin floor. The many fractures which were made weakened the basalt lava sheet along certain zones where, in recent time, the elements have worn the notches in the Holyoke Range.

Fig. 19. Block diagram showing the main features of central New England at the opening of the Cenozoic era.

Fig. 20. Block diagram showing the main features of central New England at the present time.

Streams from the eastern highland stubbornly filled up the holes and planed off the raised blocks during the entire period of intermittent movement. In the midst of the tussle between earth forces and fluvial agents the volcanoes again broke into explosive eruptions, and volcanic ash filled many of the block-like depressions all the way from Granby to localities south of Holyoke. Then the fiery vents cooled, and the earth movements diminished in their vigor. But they left a mountain front so steep that talus and landslide deposits accumulated at its base near Mount Toby; and the block mountain range was so high that glaciers may have wreathed its summit. The mountain mass descended southward, and it was penetrated by at least one low pass northeast of Granby.

In the basin itself, alluvial fans encroached from the eastern mountain front, but out in the middle of the valley ephemeral playas and shifting lakes were numerous. Rushes fringed the lake shores; fish stocked their waters; and dinosaurs lumbered over the adjacent flats. The region was one of violent rains and seasonal droughts, of hot days and frosty nights—a semi-desert country lying in the lee of the Appalachian ranges, somewhat as the intermontane valleys of the West lie in the rain shadow of bordering mountains. Eight thousand feet of sediments poured into the Triassic trough while these conditions lasted, but the situation altered slowly as the Jurassic period dawned.

Throughout earth history, vulcanism and mountain-making have been spasmodic events; but so long as rain has fallen and water has run downhill to the sea, the unspectacular rivers have never relinquished their task of reducing the lands to the lowest grade on which water will flow. During all of the Jurassic and Cretaceous periods, and even into the Eocene epoch of the Tertiary, New England’s rivers worked towards this end, and they came as close to attaining their goal as the restless earth has ever permitted them to do. The region from the Atlantic to the bases of the Green Mountains and the White Mountains was reduced to a broad, faintly terraced erosional plain. Not all of it was leveled, for Mount Wachusett, Mount Monadnock, the summits of Mount Greylock and Mount Ascutney resisted the wear and tear of the weather and of running water, and retained some of their original stature. At the headwaters of the streams the Green Mountain chain and the White Mountains also withstood reduction to the common level, forming the divide between St. Lawrence and Atlantic drainage. Such rivers as the Merrimack, the West, the Deerfield, and the Farmington followed somewhat different courses than they do today, for some of the drainage heading in the Western Upland of New England flowed straight across the red-rock valley to the sea.

During Tertiary time the entire region rose vertically as a unit. The rise was intermittent, punctuated by long stillstands of the upland with respect to the sea. One of the earlier uplifts carried the land some 200 feet higher; and although the rivers maintained their courses, they deepened their valleys and ultimately widened them into broad, open plains far back towards their headwater reaches. In the resistant rocks on either side of the red-rock basin the valleys were sharp and well defined, but in the soft Triassic sediments the rivers cut wide swaths, nearly eliminating the low divides which kept them in their independent courses.

In Middle Tertiary time renewed uplifts occurred, and ultimately the strathed surface was elevated 1,800 feet inland at the Green Mountain divide. Once more the rivers started busily cutting down; but in a protracted stillstand, while the New England upland still lacked 700 feet of its present elevation, the Atlantic Ocean planed off the hills in southern Connecticut as far north as Middletown, and the Farmington River adopted a more direct route across the marine plain to the sea. Before the West, Deerfield, and Westfield Rivers could lower their channels to grade in the reinforced rocks of the Eastern Upland, a tributary of the Farmington worked headward along the poorly consolidated red rocks of the basin and diverted the waters of the northern streams into its own channel. This was the birth of the Connecticut River, and in late Tertiary time, the energies of the new-born stream were effectively expended widening the whole of the Triassic basin. Even some of its larger tributaries developed wide valley floors with steep walls in the hard crystalline rocks of the uplands. Only the lava flows and the buried old-rock mountains withstood planation in the red-rock basin. The flows form such trap ridges as Greenfield Ridge, the Mount Holyoke Range, the Mount Tom Range, the Hanging Hills of Meriden. Exhumed mountains are typified by Mount Warner.

All of northeastern North America was raised to great heights in late Pliocene time, and the Atlantic Ocean withdrew at least fifty miles southeastward from the present shoreline. The rejuvenated rivers deepened their valleys, forming narrow, sharply incised canyons like the gorges of the Hudson and the Saguenay; and the Connecticut made a deep groove in the lowland floor, cutting to depths which have been partly disclosed by drilling at the Calvin Coolidge Memorial Bridge and the Sunderland Bridge.

While the land stood in this high position, one winter’s snow in the White Mountains failed to melt before the next began to fall. Snowfall accumulated upon snowfall, covering not only the White Mountains, but all of Canada and New England; and the Ice Age was here to stay more or less continuously for a million years. The ice piled up against the highest mountains and ultimately rose so far above them that it slid over their tops without attempting to detour around them. Its surface may have been 13,000 feet above sea level in northern New Hampshire, and its surface slope, which is estimated at 150 feet per mile, would give a thickness of 10,000 feet at Northampton. The continent yielded slowly under this great load, and it sank until all of the elevation gained in the Pliocene movement was wiped out, and more besides. The ice radiated from the centers of maximum accumulation—at first from the White Mountains, and then from northern Ontario, and finally from Labrador. The continental glacier crept southward to Long Island and Martha’s Vineyard, where its front melted in the waters of the Atlantic as fast as new ice came up behind. It dragged and pushed and carried debris, only to dump it in a hummocky ridge, like a rampart, to mark its farthest advance.

At last the glaciers started to melt even faster than new masses moved down from the north, and the ice front began to recede 400 to 700 feet per year. The sea followed it, up the Hudson, up the St. Lawrence, in over the coastal lowlands for a short distance; and everywhere pounding waves made beaches at the water line. And in the path of its slow, deliberate retreat, the glacier left rock debris—boulders on the hills and in the valleys, boulders everywhere; all the landscape was marred and desolate.

The ice had weighed the pre-glacial valleys down more deeply in the north than in the south. One such valley was the Connecticut Lowland, in which water gathered to overflow-height at Middletown. Thus Lake Springfield came into being, and it spread northward as the ice front receded. North of the Holyoke Range another lake formed, and this northern body of water has been named Lake Hadley. Streams flowed off the ice, off the hills—flowed with unimpeded vigor, for there were no trees or grass to retard the run-off. Deltas grew out from the shores, and annual layers of clay settled on the lake bed.

The ice grew thinner, its area smaller, and its load lighter; and as Mother Earth lost her heavy burden, the land rose, more in the north than in the south. The differential rise decanted the water southward out of the lake basins, and the seas retired from the coastal lowlands. Old shores and sea beaches remained as flat terraces sloping gently southward. The rivers raced down the steep beach slopes to the old lake floors and sea bottom. They cut their channels deeply into the unconsolidated deltas and meandered back and forth over the flat, ungraded lacustrine plains, as if uncertain where to flow. They flooded the lands in the spring, leaving loose sand and silt for the winds to blow when the water was low. Sand dunes rose near the river banks at North Hadley, Sunderland, Hatfield, and South Deerfield; but the march of the dunes was arrested as post-glacial vegetation repossessed the land. It was at this point in the story that man found and settled the Connecticut Valley, becoming a witness to the geologic work of the river and an aid to the work of the wind as his plow bared the fertile soil to the elements.

Interesting Places

Books and periodicals supply dinner menus for the hostess and list theatrical offerings for the habitué. Surely suggestions of places for a picnic or an evening drive are equally in order. Experience, some of it painful, soon reduces the number of pleasant picnic sites: poison ivy or a deceptive bog may linger in the memory and automatically eliminate some otherwise delightful spot. But places suitable to every taste lie within the Connecticut Valley or along its fringing uplands. Some are near the highways and others are on woodland trails; a few are interesting for their immediate surroundings and many because of their expansive view. Here is a landscape which can be appreciated without leaving or stopping the car; but there is a sight which can be relished only from a trail, or from a pinnacle accessible to the agile climber. Drives satisfy some tastes; but places to stop, meditate, and conjure up the past appeal to others. The Valley and its environs have something for every temperament and every mood.

Mount Lincoln in Pelham

Mount Lincoln is remote enough from highways to offer some measure of retreat, yet it is not discouragingly inaccessible. The summit rises about 300 feet above the nearest road, which lies a mile away by woodland trail. It is Pelham’s highest eminence, and its height is enhanced by a fire tower which affords a magnificent view in every compass direction.

The gently undulating New England upland stretches off to the north and east for miles. The innumerable hills which compose it integrate to form a horizontal skyline, which suggests a flat erosional plane, originally formed at, or near, the level of the sea. To the northeast Mount Monadnock in New Hampshire rises prominently above the general level, for its extremely resistant rock withstood reduction by weather and water more effectively than the weaker bedrock on every side.

The valley lowland begins but three miles to the southwest. The range of hills stretching away like beads on a string is the Holyoke Range. Mount Toby, Mount Sugarloaf, and the Pocumtuck Hills are the prominences in the lowland to the northwest. The lowland was eroded out of the New England upland after the land was elevated far back in Tertiary time, and the disintegrating rock was carried to the sea by the rivers. The hills in the lowland were left where the rocks resisted destruction more successfully than elsewhere, but they only approximate the level of the upland of which they were once a part.

Mount Lincoln and the surrounding hills are strewn with boulders. Every slope is dotted with large irregularly shaped rocks, many of which have smoothed facets marred by minute scratches. The boulders were left by the Great Ice Sheet when it melted off New England, and the scratches were made when the ice dragged the boulders over hard rock surfaces. These stones came down from the north, and among them you may recognize types which you have seen in the ledges around Orange and Northfield. Early Pelham settlers found the boulders as much in their way as the trees; so they burned or used the trees, and they piled the stones in long rows to fence their fields. Stone fences characterize all glaciated regions, and here they follow the roadsides for miles, reaching to the edge of the deposits in glacial Lake Hadley.

Mount Toby

“Let’s go to Mount Toby” usually means to go to the camp ground along Roaring Brook at the east base of the mountain, or to one of the sugar camps on the west slope, or to the Sunderland Caves at the north end. All of these places are worth knowing, but the view from the mountain top deserves at least one trip, and the wood road from Roaring Brook is replete with interesting sights.

Pl. 6. View of the Holyoke Range from Mt. Lincoln.

Fig. 21. Map showing location of interesting places.

1. Davis pyrite mine 2. Plainfield manganese mine 3. Lithia spodumene pegmatite 4. Chesterfield tourmaline locality 5. Westfield marble quarry 6. Williamsburg galena vein 7. Hatfield lead mine 8. West Farms lead mine 9. Loudville lead mine 10. Westfield trap quarry 11. Bernardston magnetite mine 12. Gill dinosaur track quarry 13. Mount Toby 14. Sunderland Caves 15. Roaring brook 16. Whittemore’s Ferry fish quarry 17. Mt. Sugarloaf 18. Leverett lead vein 19. Notch quarry 20. Northampton granite quarry 21. Titan’s Piazza 22. Titan’s Pier 23. Ox-bow lake 24. Smith’s ferry dinosaur tracks 25. Varved clay pits 26. Mt. Grace 27. French King bridge 28. Mt. Lincoln 29. Pelham asbestos mine

The side road to Roaring Brook leaves the highway east of Mount Toby just north of the old cemetery, and the camp site is on the west side of the Central Vermont Railway tracks. The gray rocks east of the tracks are part of the ancient mountains of Triassic time. Their lofty summits have been worn away by the unceasing activity of weather and running water, and they are now lower than the fans of waste which was discharged from the ancient valleys. Roaring Brook is continuing the work of erosion as it tumbles down from Mount Toby, and frost has loosened the great boulders that lie on the mountainside.

The rock along Roaring Brook is very different from that east of the railroad. It looks a great deal like concrete, with a large assortment of aggregate materials mixed in with the cement. The rock is conglomerate, a mass of coarse stones washed out of the ancient Triassic mountains, deposited at their base and in contemporary stream valleys, and then cemented during the ensuing ages. Many of the pebbles in the conglomerate cannot be found in the old rocks east of the railroad tracks. Actually these rocks change in character at different levels in the uplands of today, and still higher changes which were present in this mountain group during Triassic time have been destroyed, though the record of their presence has been retained in the fragments which compose the conglomerate.

The woodland trail starts up the mountain about 100 yards north of the picnic grounds. The rock beside it is red granite, and the streams of Triassic time flowed over it as they carried the gravel which now makes the Mount Toby conglomerate. The latter first appears about 100 feet uphill, and it is virtually the only rock exposed from this point to the summit. Interspersed sandstone beds disintegrate easily and form quiet pools and basins in the adjacent brook; the pools end a few feet upstream where the water cascades over the edge of the next higher conglomerate stratum.

Mount Toby’s summit rises above any other eminence in central Massachusetts east of Ashfield and south of Mount Grace near Northfield. From it the entire country to the south appears low and flat, except for the teeth of the Mount Holyoke Range and the long ridge extending southward from Mount Tom. A slope rises westward from the lowland to meet the edge of the flat New England upland along a line that passes through Shelburne, Conway, Goshen, and Granville. East of Toby this same upland comes so close that it seems but a step across to it.

Many peaks may be seen rising above the New England upland. The one far to the east is Wachusett. Up there to the north-northeast are Monadnock and Mount Grace. Over in the northwest are Stratton and Glastenbury in Vermont, and much nearer and lower is Bald Mountain at Shelburne Falls. Mount Greylock, the highest point in Massachusetts, is almost due west.

The lowland was excavated after the New England upland was elevated, and the main features which distinguish the present landscape were carved out before the end of the Miocene epoch of Tertiary time. The high points which surmount the upland are monadnocks which, like their prototype Mount Monadnock, successfully resisted the ravages of time and New England’s changing but rigorous climate.

The Sunderland Caves

The Sunderland Caves are on the northwest side of Mount Toby, just a short walk and an easy climb from State Highway 63. They penetrate a cliff made of conglomerate overlying a shale which accumulated in a Triassic lake. The shale makes the floor of the cave. Joints, forming a right angle with the cliff, break the conglomerate into giant blocks. Frost, smooth shale surfaces, and gravity have caused the two end pieces to creep away from the other conglomerate blocks. The second block from the end has fallen against the end block, forming a high-roofed cave about 100 feet long.

Directly southwest of the lower entrance to the cave, the shale beds are highly distorted along the borders of a trough-like mass of angular conglomerate or breccia, in which boulders up to six feet in diameter are numerous. It is believed to be the record of a Triassic landslide, which avalanched down the mountain front immediately to the east, and into the old lake at the mountain base. It plowed up the clays in the lake bed, carried some of them away, and furrowed the others into the crumpled forms that are clearly visible along the path to the caves.

Mount Sugarloaf

Mount Sugarloaf does not offer Mount Lincoln’s retreat from crowds nor Mount Toby’s expansive landscape, but it is accessible, and it provides an unrivaled view of the valley between South Deerfield and the Holyoke Range. Its red sandstones and conglomerates rise almost sheer for 500 feet above the Sunderland-South Deerfield road. On the northwest and southeast sides the cliffs are determined by nearly vertical joint planes. During the Ice Age, the southward-moving glacier plucked away the loosely attached blocks facing the South Deerfield and Sunderland sections of the lowland, leaving Sugarloaf as a remnant between the joint surfaces.

The great bites which the meandering Connecticut River has taken out of the lowland are visible east of Sunderland village and south towards Hatfield. Each arc in the edge of the scalloped flood plain is the extremity of a meander loop which the wandering river carved in its bank and then abandoned by breaking through the narrow base or tongue, as it did at the Northampton ox-bow.

An area of low, rolling, sandy hills extends through the pine woods for a mile southward from South Deerfield. The hills are dunes which formed when the Connecticut was picking its channel across the newly exposed and barren bed of glacial Lake Hadley.

Fig. 22. Meander scarps form a margin to the Connecticut River flood plain at Sunderland.

The panorama from the west side of Mount Sugarloaf centers about the deep gorge of the Deerfield River. The top of the gorge widens out into a broad strath and affords a glimpse of the more remote upland. The river, emerging from this canyon during post-glacial time, built a huge delta into glacial Lake Hadley, and much of the delta still remains in the terrace which is utilized by the Boston and Maine Railroad as it descends into Greenfield.

Turners Falls

Rushing water has a fascination which was frankly recognized by the highway engineers who made the parking place facing the Connecticut where Route 2 passes along the north side of Turners Falls. Here the river drops over a series of sandstone ledges into a deep and narrow channel at the east base of the trap ridge. Waterfalls are not common in rivers flowing through lowlands; they indicate disturbances of normal stream development and sometimes change in course.

The Connecticut Lowland is old, but its ancient drainage lines were buried by the deposits left in glacial Lake Hadley. The river’s present course was established upon these lacustrine sediments, and the inner valley plain is excavated in them. Before entrenchment took place, the south-flowing reach of the river above Millers Falls was deflected westward across the lake plain by the delta of Millers River. It was turned southward once again by the trap ridge near Turners Falls. The river soon cut through the unconsolidated lake beds and found that it was out of its pre-glacial channel. The delta of Millers River had diverted the water from the old rock valley beneath the Montague sand plain, across a rock divide, and into the pre-glacial valley of Falls River. The lake-fill in Falls River has been almost completely removed, and Turners Falls now mark the spot where the Connecticut pours over the bank and into the channel of its pre-glacial tributary. The falls have receded upstream several hundred feet and have cut a deep gash in the Triassic rocks.

Pl. 7. Gorges, in highland and lowland alike, were formed when the rivers were superimposed on coherent rock.

a. View of the Deerfield River gorge emerging on valley lowland as seen from Mt. Sugarloaf.

b. View of the French King gorge as seen from the bridge.

Turners Falls are the product of a series of coincidences. First, the ice sheet and Lake Hadley buried all established drainage lines and forced the streams to adopt new routes over the bared lake bottom. While the lake existed, Millers River threw a weak obstruction in the path of the Connecticut, diverting it to that part of the lowland where one of its pre-glacial tributaries had excavated a slender rock gorge along a fault plane. The river washed the lake deposits out of the gorge, exposed the old bank of Falls River, and was busily cutting a new gorge back into this bank when the dam was constructed and its erosive activities were suddenly arrested.

The French King Bridge

The highway from Greenfield to Athol and Fitchburg passes Turners Falls and crosses the Connecticut River near Millers Falls by way of the French King Bridge. Here the roadway is more than 130 feet above the water level. A picnic ground and parking place at the west end of the bridge make it a particularly attractive place to stop and enjoy the view upstream towards Northfield.

The river occupies a narrow rock gorge for a mile north of the bridge, but at that point the valley widens out. This entire section of the river’s course was established on the old bed of glacial Lake Hadley; but after the unconsolidated deposits were washed away, the stream found itself flowing along the weak contact between the Triassic conglomerate on the west bank and the metamorphic rocks of the highlands on the east bank. The river deepened its channel on the weak contact zone and made the scenic cut over which the bridge was built.

The pre-glacial valley lies beneath the sand plain east of the river. Millers River crosses this old valley between Millers Falls and its confluence with the Connecticut, at the east end of the bridge. The rapids at the junction can be traced to the ridge of crystalline rock between the east bank of the present Connecticut and the west bank of the pre-glacial Connecticut. The resistant ledge forms a barrier which Millers River has not yet eroded to its grade.

The conglomerate beds on the west wall of the gorge dip steeply eastward towards the river and end against the crystallines. The beds were originally laid down with a gentle westward inclination. They were tilted steeply in the opposite direction against the crystallines by faulting, which elevated the ranges and pressed down the adjacent basin during Triassic time.

Titan’s Piazza and Titan’s Pier

Not so long ago, giants and the devil received the credit or the blame for such oddities in nature as rock-masses broken into six-sided columns. Ireland has its Giant’s Causeway, and Yellowstone National Park its Devil’s Post-pile. Titan’s Piazza and Titan’s Pier were likewise attributed to activities of the leader of fallen angels and were given names appropriate to such an origin by the early settlers. Dr. Hitchcock, in characteristic fashion, undertook the task of correcting the errors of puritanical psychology by renaming these places during one of the early Mountain Day trips from Amherst College. The entire college body sojourned to the west end of the Holyoke Range to hear the cliffs renamed and their true nature explained.

Devil or no devil, those huge columns had a hot origin. The dark rock in them is part of the main lava sheet which stretches across the valley in the Holyoke Range and swings southward in the Nonotuck—Mount Tom Range. The lava poured out of a series of volcanoes which were strung out along a fissure about three miles to the east, and the molten mass had a temperature of 1200° to 1300° C. The hot lava radiated its heat to the sandstone below and to the air above; and, as it cooled, it contracted like any other substance. The shrinkage was so great that series of cracks formed in regular pattern, with each crack perpendicular to the cooling surface. The stresses producing the fissures were equal in all directions and would have made circular cracks and cylindrical columns; but cylinders have non-cylindrical spaces between them, and the pattern in which the columns are most nearly cylindrical and yet completely occupy all space is hexagonal. So contraction broke the lava into hexagonal columns perpendicular to the cooling surface. The columns are parallel where the lava floor is regular but are curved or radial where the floor is rolling.

Pl. 8. Trap ridges, near and far.

a. View of Titan’s Piazza at Hockanum showing the columns resting upon the gently inclined sandstone.

b. View of the Springfield lowland from the Westfield marble quarry. The Wilbraham Mts. appear in the distance. The trap ridge extends through the middle and is breached by the Westfield River.

The columns on Titan’s Pier lie across the river from the Northampton-Holyoke road in the narrow gap at Mount Tom station. The basalt flow is inclined 15° southeastward, and the columns stand perpendicular to the surface—hence they are inclined with respect to the water level. Doubtless the devil docked his boat on the gently inclined rock surface of the cove on the downstream side of the pier.

Titan’s Piazza is situated east of the road to the Mount Holyoke House. It is an extremely narrow ledge backed by a stockade of columns. The front of the piazza is literally strewn with wreckage from the house, for a slope over 100 feet high is covered with angular pieces of basalt which have fallen from the back wall. The lower ends of the columns break off into shallow hexagonal saucers with the concave sides up. Many have slid down the slope, to the delight of the birds that bathe in them. Higher up the cliff, the saucers become deeper, and towards the top the columns scale on into bullet shaped masses.

Westfield Marble Quarry

Anyone who drives westward on the Jacob’s Ladder route from Springfield passes first through the open, rolling country of the Connecticut Lowland. Hills are in sight, but they seem remote until he leaves Westfield, and there the upland rises before him like a 900-foot wall. The road uses the gateway cut in the wall by the Westfield River, and the drive westward towards the headwaters of the river is one of the best known scenic attractions in western Massachusetts. But a greater treat awaits the person who will venture southward on the road along the Little Westfield River. It follows the canyon brink about 500 feet above the stream. Near the hilltop, a side road turns north to the Westfield Marble quarry, which provides a vantage point overlooking fifty miles of country to the north, east and south.

The Westfield River meanders eastward across the flat lowland. Its banks are terraced, each level cut in the lake beds or in the delta which the river built in glacial Lake Springfield. The scalloped margins of the terraces are the extremities of meander loops which developed when the river was not entrenched as deeply in the unconsolidated deposits as it is today.

The flatness of the twenty-mile strip of lowland is impressive, for it ends only at the Wilbraham Mountains, eight miles east of Springfield. Beneath the lowland lie soft and gently dipping sandstones and sandy shales, capped by a thin veneer of lake clays and river sands. The shales are the youngest Triassic beds remaining in the region, and they outcrop between Thompsonville and Windsor Locks, Connecticut. Younger shales above them succumbed to Tertiary erosion.

The Wilbraham Mountains are granite and gneiss which formed the roots of the ancient Triassic ranges. Their present accordant summits are a tribute to the leveling activities which running water performed on a quiescent land, whereas the deep V-shaped valleys incised in the level summits record uplift and quickened erosion in Tertiary and glacial time. Indeed, the lowland itself owes its existence to the power of rejuvenated streams working on non-resisting rocks.

The Holyoke and Mount Tom ranges are visible far to the northeast, and a chain of low hills connects Tom with the ridges between Hartford and Avon, Connecticut. These linear hills surmount the lowland because they are made of basaltic lava, which is better able to resist the rain and the weather than the sandstones and shales above and below. Scattered flat-topped hills between Southwick and Granby are sheets of basalt-like rock called diabase, which was inserted between a sandstone roof and floor. Nowhere can one better appreciate the highly individualized imprint which each geological element has made upon the central New England landscape.

The Old Lead Mines

The colonial period in our nation’s history was characterized by an ignorance of its mineral wealth and a dependence upon Europe for most raw materials, especially essential metals. During the War for Independence, European supplies were cut off, and Yankee ingenuity had to make the most of local deposits of metallic minerals. It was not long before mines were in operation on several lead veins in the Connecticut Valley, yielding a supply of lead for the duration of the war. But the mines were small, and most of them were soon abandoned, remaining only as historical sites, or as collecting localities for the mineralogist. Five of these old deposits are still accessible: four lie west of the valley at Loudville, West Farms, Hatfield, and Williamsburg; an important one is situated east of the valley at Leverett. All are very similar in geology and mineralogy, yet each possesses its own individuality.

The Loudville vein was worked intermittently as late as 1861. It follows a fault fracture between walls of gneiss, but at the southwest end of the vein some of the minerals are disseminated through the Triassic sandstone and conglomerate. This feature indicates that the sediments were unconsolidated at the time of mineralization. The fault zone resembles many analogous fissures which give forth hot mineral-bearing waters in the Basin and Range region of Nevada, for the charged waters have impregnated the sands which cover the fissures.

The Loudville vein contains numerous well-formed crystals. Barite was the first mineral deposited, and it is readily recognized as a heavy, easily scratched substance with one set of cleavage planes at right angles to two others. Gray metallic galena and resinous cleavable sphalerite or zinc blende occupy much of the space between the barite plates. Hard hexagonal crystals or white masses of quartz coat and even replace the barite plates. Spike-shaped crystals of calcite and siderite line many of the cavities and coat the quartz. A patient search will be rewarded by the finding of other minerals, including pyrite, chalcopyrite, pyromorphite, wulfenite, malachite and azurite.

The old shaft has been closed and the tunnel at the river level has collapsed, hence the only exposures are in the open cuts. The most interesting is the one at the south end, where the barite plates are disseminated through the sandstone.

Another series of pits can be found easily about 100 yards west of the road to West Farms and about one mile north of the Loudville deposit. The vein attains a maximum width of three feet between walls of gneiss, and it occupies a fault fracture which seems to be continuous with the Loudville zone. Included in the vein are many fragments of a black phyllite resembling the Leyden argillite, as well as pieces of gneiss. The minerals are identical with those found in the Loudville deposit, but the specimens of quartz, galena and sphalerite are more spectacular.

The Hatfield vein occurs in a rock of igneous origin, known as the Williamsburg granodiorite. It is exposed at the west edge of the valley, about 200 feet from Federal Highway 5, at the northern limit of the settlement called West Hatfield. The workings are full of water, and the very thorough mining activities carried on by mineral collectors and by Smith College and Amherst classes have reduced the waste pile to negligible proportions. Early collections and records reveal that the vein is essentially like those farther south. At Hatfield, West Farms and Loudville the fractures do not parallel the systems in the Triassic sediments and lavas.

A galena-bearing vein outcrops near the Whately-Williamsburg town line at the north end of the Northampton reservoir. Leyden argillite forms the walls of a fault fissure. Barite is absent from this vein, but fine quartz, pyrite and chalcopyrite coat the walls. Coarse comb quartz encrusts the older minerals, together with breccia fragments and cubes of galena. The vein is remote from the valley and differs in mineralogy and texture from those within the valley. Other deposits like it have been found in the nearby hills.

Fig. 23. Geologic map of the region in the vicinity of the lead veins near Leverett.

1. Only barite in these veins 2. Best mineral locality 3. Best place to see fault 4. Slickensides and tension cracks show direction of movement on fracture making opening for vein 5. Best place to see quartz replacing barite along crush zones in vein

The Leverett lead vein is the most interesting of the group because it is so well exposed that the nature of the vein system is admirably displayed. The deposit lies in a series of overlapping, nearly vertical fault fissures in gneiss. Slickensides and tension cracks on the walls of the veins indicate that the movement was nearly horizontal from northeast to southwest. Wherever a fracture begins to narrow and close up, another begins to widen and become conspicuous a few feet to the northwest of it. Several different fissures appear along the length of the mineral zone.

The same minerals are present as are found in the Loudville, West Farms and Hatfield veins, but barite is more abundant and quartz less so. Numerous cavities lined with crystals indicate that the vein formed close to the earth’s surface. Apparently the minerals entered fractures situated near the front of a range that bordered the basin in Triassic time. A fault zone so located would lack the great thickness of rock that once lay over the gneiss and would be free from any appreciable overburden of outwash within the Triassic basins.

The Dinosaur Tracks Near Holyoke

People still write from as far away as the Rocky Mountains to ask if the dinosaur footprints beside the Connecticut River are still in place. They are. Anyone may see them in that triangular area between the Boston and Maine tracks and Federal Highway 5 about one-quarter mile north of the entrance to Mountain Park. Marvelous as their preservation from the assaults of man may seem, it is even more amazing that they should have been preserved in rock at all.

Pl. 9a. The dinosaur track preserve at Smith’s Ferry near Holyoke.

Pl. 9b. Varved clays or calendar beds on river bank south of Hadley.

The footprint beds are shaly sandstones about thirty feet above the Granby tuff—a bed of volcanic ash formed in late Triassic time. They are inclined 15° towards the river, and even the higher strata which form the “Riffles” are footprint-bearing. The sandstones are ripple-marked, and they contain worm trails and a few casts of salt crystals. Some beds have impressions of reeds. The footprints range from half an inch to ten inches in length, and the stride of the larger animals was from five to eight feet. Most of the tracks are headed up the present slope, but a few are going in the opposite direction.

The sandstones were laid down as almost horizontal beds of sand which were occasionally covered and rippled by moving but rather shallow water. Rushes and reeds, which have left stray impressions in the rock, grew seasonally in the shallow waters, but in between the periodic rains and floods, the local climate seems to have been quite dry—and probably very warm. The sedimentary record suggests a lowland much like some of the tropical valleys in the West Indies, lying in the rain shadow of adjacent mountains.

The large tracks invariably have impressions of three toes. Even a careful search does not disclose the double tracks which would have been left by quadrupeds, and for years the bipedal impressions were called bird tracks. But birds have spurs which leave a mark behind the middle toe; these animals had no spurs and were not birds, but reptiles. Gregarious animals generally follow a leader, and only an occasional individual strays from the beaten path. The tracks at Holyoke suggest that these Triassic reptiles traveled in small herds.

The modern silts of the Connecticut Valley are not a good medium for the preservation of tracks because they lack coherence, and they drift with the wind as soon as they dry. Clays in a region of seasonal aridity are different. They are baked hard in the hot sun, and the water contains dissolved mineral matter which crystallizes in the clay and sand as the water evaporates, cementing the particles into a rock-like aggregate. Impressions in this sort of mud are preserved. The Connecticut Valley had the right kind of sediment and climate in Triassic time; impressions of salt crystals can be found in the shales where the tracks are clearest, not only in this locality but elsewhere in the neighborhood of Holyoke and West Springfield. These precipitated salts helped hold the clays together until they were effectively buried, and afterwards a firmer cement was deposited around the particles.

Footprints are known near South Hadley, at Turners Falls, at Gill, and along the highway to the French King Bridge; but they do not portray the character of the animals, their habits and the mode of preservation of their tracks as effectively as the tracks north of Holyoke. Certainly no occurrence of tracks in situ is as accessible, and no geological exhibit in New England has received so many visitors.

Fossil Fishing

Many years ago men were excavating to lay a foundation for a waterwheel at what was Whittemore’s Ferry, three miles north of Sunderland. They made a catch of some of the most ancient fish ever taken in New England, but the fish were petrified and did not put up a fight.

They were found in layers of black shale, in which skeletons and carbonized tissues were well preserved. Of the five genera identified, all but one were ganoids.

The shale accumulated as mud on a Triassic lake bottom, and it was covered by a coarse stream-laid gravel which has since been cemented into rock. The mud was not eroded by the stream which washed down the gravel, and the pebbles are not even impressed into the underlying shale. Apparently the fish perished as the waters evaporated and the lake became a playa flat. The limited variety of fish suggests that the connections with outside regions were restricted, and that living conditions within the basin were rigorous. The situation may have been like that found in the fresh water lakes along the western margin of the Great Basin in Nevada and eastern California.

Other lake deposits with fish remains appear at different levels from Whittemore’s Ferry up to the Sunderland Caves. Each is covered by a conglomerate layer, and at each place the lake clays had been partially hardened before the pebbles were washed over them. Seemingly dry alluvial plains followed transient lakes in kaleidoscopic but cyclic succession.

Calendar Beds

The lakes in which the fish lived and died date back to late Triassic time. Much younger were the lakes that followed the continental ice sheets, and in many valley localities these younger water bodies have registered their brief span of geologic life. For they, too, were settling basins for clays, which are characterized by annual depositional bands like the growth rings in a tree. These clays may be examined best in the clay pits at any of the brickyards, particularly at South Hadley Falls, or beside the high river banks rising above the Connecticut flood plain just south of Hadley.

The clays consist of alternating thin, dark, fine bands and thick, light, coarser ones. The coarser bands are sandy, and some of them have ripple-marks. The total number of pairs of beds is the number of years that glacial Lakes Springfield and Hadley inundated the valley, but it is not a simple matter to count them. Actually the lake bottom deposits are but a small fraction of the total volume of material brought to the lake. Lake shore deposits and deltas grew outward and buried the bottom deposits after a few hundred years had passed. Thus in the pits at South Hadley Falls, the clays rest upon glacial gravels, and a scant hundred layers intervene between them and the sands above. Shore encroachment is not encountered at Hadley, but the shallow depth of the present water table hinders deep exploration, and the Fort River has removed many of the upper beds.

Long winters result in thick winter deposits, and heavy spring floods cause thick sand layers. If the winter of any year is long at Northampton, it is usually long everywhere in New England; and if the Connecticut has floods, most neighboring drainage systems have them, too. In this way, similar layers, or similar successions of layers, are formed at different places at the same time; and the lake deposits at White River Junction, Deerfield, Hadley, South Hadley Falls, Chicopee and Springfield may be matched and dated with respect to each other. The complete record in the valley shows that, in the vicinity of the Holyoke Range, the lake came into existence about 18,000 years ago.

In each of the clay pits every set of lines exposed on the working faces represents a year, and the deposit as a whole is a calendar—in fact, it is also a thermograph for part of the region’s post-glacial history. Some bands at South Hadley Falls and along the Hadley river bank are highly distorted, and the distorted layers are planed off smooth. Spring sand covers the distorted beds. The disturbance can be attributed to ice which froze to the lake bottom and dragged the clay layers as it expanded and contracted with changes in temperature.

Locally the clays are exceptionally hard about certain centers, forming clay stones or concretions. A willow twig or shell or some organic substance is commonly present at their cores. Groundwater has deposited calcium and iron carbonate about the adjacent clay particles and cemented them into rock.

The Holyoke Range

For years it has been a popular outdoor pastime to “walk the Range.” The distance is neither so great nor the route so rugged that it cannot be covered in the course of an afternoon, even if ample time is allotted for stops at the many lookouts. The latter provide ever changing views of the valley from Greenfield and beyond, to Meriden, Connecticut. The buildings in Hartford are easily visible on a clear day. The trail follows the crest of the Range closely and only rarely leaves the basalt lava flow. The trip is somewhat less arduous from west to east than it is in the opposite direction, and the view from Bare Mountain is a pleasant climax for those ending their hike at the Notch.

At the toll booth the trail leaves the road which ascends to the Mount Holyoke Hotel and angles upward along the mountain slope. Overhead the dark basaltic lava columns rest upon red and white Triassic sandstone, and the path soon crosses the contact between the two types of rocks. A short distance above the contact the trail takes advantage of a col and climbs to the top of the ridge. Down the steep southeasterly slope Mount Holyoke College appears in the distance through a screen of oak trees.

The remainder of the climb is gentle, and soon the path enters the clearing around the hotel. The view is arresting. The Connecticut emerges from behind Mount Sugarloaf, wanders through the Hadley fields, flows through the watergap just west of Mount Holyoke, and disappears far to the south beyond Springfield. Northampton is spread out below. Automobiles on the Hockanum Road look like so many moving dots. The hills between the Range and South Hadley are made of volcanic ash and lava; many have pipe-like cores which were the necks of ancient volcanoes. Off to the east are higher points on the Range which lie on the route to be followed.

The path continues along the crest of the range and descends gradually to the toll road level at Taylor’s Notch. Here it is on sandstone, and the lava-sandstone contact is exposed on both sides of the gap. Sandstone cliffs rise fifty feet high a few yards down the road; and the fine arenaceous character of the rock and its bedding are visible at some distance.

The trail climbs steeply from this col and soon skirts the edge of an abrupt cliff, in which are carved the initials of many hikers who paused on the ledge to rest and to enjoy the panorama. Eastward the path might well serve as the model for a roller coaster in an amusement park. “The Sisters” are a series of hills separated by sharp, deep valleys; and no sooner has one attained a summit than a drop down the other side is in order. Abrupt 30-foot cliffs trending north and south form many of the valley margins; they are smooth joint surfaces where the rock is weak, and where blocks were plucked out by the great Ice Sheet. Each of “the Sisters” has a cleared lookout which affords a new picture of the Hadley-Deerfield lowland to the north.

The last lookout is some distance below the succession of summits, and it affords a view to the east. A cliff drops 200 feet vertically, and about one-quarter of a mile farther east other cliffs of red-weathering basalt face towards it. Almost all of the broad, low gap between the cliffs is underlain by a complicated mixture of volcanic ash, agglomerate and irregular lava flows. The cliff itself is thick columnar basalt, and at its base is a coarse sandstone. But the sandstone is thin and disappears in the depression, whereas the agglomerate and lava become very thick and extend northward to the top of “Little Tinker” and the “Tinker.” They are part of an ancient volcanic cone, buried in sandstone both to the east and to the west. Flow structures in the main sheet move away from this center, which is believed to have been one of the volcanoes on the line which supplied the basalt for the great lava field.

In the depression, the trail winds between hills of twisted lava and consolidated agglomerate. When the trees are leafed out and the surrounding hills concealed, it is easy to imagine oneself on the slope of a Pacific volcano. The trail divides at the lowest point in the depression, and the less used fork goes north to the Bay Road at the northern base of the Range. The other fork ascends Mount Hitchcock, and at a slight elevation above the low flat it crosses from the agglomerate to the Holyoke basalt sheet.

The best lookout on the Range between the Mount Holyoke Hotel and Bare Mountain is on top of Mount Hitchcock. A side trail leads out to a promontory, from which one may peer along the face of the Range, look down upon the “Tinker” and “Little Tinker,” and gaze over the lowland which the Connecticut has excavated in the New England upland through the long course of geologic time.

The east slope of Mount Hitchcock descends steeply, and many a hasty hiker has made the trip in less time than he intended. The path drops to a flat which measures about 1,000 feet across, and in which the sandstone lying below the lava sheet is sporadically exposed. Here the thick basaltic lava has been worn away; and erosion ceases both east and west at conspicuous fracture surfaces which locally become fault planes.

Beyond this low notch the trail leads irregularly upward and eventually comes out on Bare Mountain. The top is bare indeed; even scrub oak is absent from the summit. The long south slope of the Range is clearly visible, and to the west is the Mount Holyoke Hotel where the hike started. The Mount Tom Range, with the Connecticut River at its foot, is just to the left. Due south are the towers of Mount Holyoke College and the cities of Holyoke and Springfield. If the day is clear, the tall buildings of Hartford appear in the far distance. Six hundred feet directly below, the highway goes through the Notch, and across the road is the trap quarry in Notch Mountain, which supplies the crushed stone for the local highways. The face of Notch Mountain lies north of the main line of the Range because the basalt sheet has been displaced northward between fault planes that bound the eminences on either side. The notches utilized by the highway and by the power line are due to facile erosion of the crushed rock along the fault planes. Farther to the east, Mount Norwottock rises to the greatest height in the Range, and the view from its summit is at least the equal of that from Bare Mountain. The Hadley lowland stretches northward between the Pelham Hills on the east and the Berkshire Hills on the west, and protruding above its relatively flat surface are Mount Warner, Mount Sugarloaf and Mount Toby. The Deerfield gorge trenches the western upland just west of Sugarloaf, and on the skyline is Glastenbury far off in Vermont.

Fig. 24. Diagrams showing the stages in development of topography in the vicinity of the Notch.

a. The New England peneplain stage at the Notch.

b. The incoherent rocks are removed from the lava flow.

The flow of time in the Connecticut valley

The Flow of Time
IN THE
CONNECTICUT VALLEY

Contents

Plates

Figures

Introduction

Today and Yesterday

The River Works

The Landscape Changes

Glaciers Came

Just Before the Ice Age

Rivers Carried Off the Everlasting Hills

Before the Rivers Cut the Valleys

The Mosaic of Central Massachusetts

The Red Rock Basin

A Dinosaur Diary

Volcanoes

The Original Valley

Hot Springs in Central Massachusetts

The Marginal Uplands

The Eastern Upland

Coal Swamps in Massachusetts and Rhode Island

The Western Upland

The Story of Central Massachusetts

Interesting Places

Mount Lincoln in Pelham

Mount Toby

The Sunderland Caves

Mount Sugarloaf

Turners Falls

The French King Bridge

Titan’s Piazza and Titan’s Pier

Westfield Marble Quarry

The Old Lead Mines

The Dinosaur Tracks Near Holyoke

Fossil Fishing

Calendar Beds

The Holyoke Range

The flow of time in the Connecticut valley

The Flow of TimeIN THECONNECTICUT VALLEY

Contents

Plates

Figures

Introduction

Today and Yesterday

The River Works

The Landscape Changes

Glaciers Came

Just Before the Ice Age

Rivers Carried Off the Everlasting Hills

Before the Rivers Cut the Valleys

The Mosaic of Central Massachusetts

The Red Rock Basin

A Dinosaur Diary

Volcanoes

The Original Valley

Hot Springs in Central Massachusetts

The Marginal Uplands

The Eastern Upland

Coal Swamps in Massachusetts and Rhode Island

The Western Upland

The Story of Central Massachusetts

Interesting Places

Mount Lincoln in Pelham

Mount Toby

The Sunderland Caves

Mount Sugarloaf

Turners Falls

The French King Bridge

Titan’s Piazza and Titan’s Pier

Westfield Marble Quarry

The Old Lead Mines

The Dinosaur Tracks Near Holyoke

Fossil Fishing

Calendar Beds

The Holyoke Range

The Flow of Time
IN THE
CONNECTICUT VALLEY