Part 2

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.

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.

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.