Chapter I: Front Matter (1)

_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

COPYRIGHT, 1942, BY THE HAMPSHIRE BOOKSHOP

Contents

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

1. The Connecticut River undercuts the Hadley bank 2
2. Natural levees south of the Sunderland Bridge 2
3. Block diagram showing main features of central Massachusetts at
the present time 5
4. Block diagram showing main features of central Massachusetts
during recession of the Ice Sheet 5
5. Block diagram showing main features of central Massachusetts
during excavation of the lowland 13
6. Block diagram showing main features of central Massachusetts
after Triassic basins were filled 13
7. Map of Mount Toby showing gorges filled with conglomerate 20
8. Map showing agglomerate burying a fault scarp on Notch power
line 24
9. Block diagram showing main features of central Massachusetts
during volcanic stage 27
10. Block diagram showing the Triassic basins of central
Massachusetts 27
11. Map of old volcanic region near Mount Hitchcock and west of
the Notch 29
12. Block diagram showing topography during formation of the lead
veins 31
13. Block diagram of region during Middle Ordovician time 39
14. Block diagram of region at end of Ordovician time 39
15. Block diagram of region during Devonian period 39
16. Block diagram of region during Carboniferous period 41
17. Block diagram of region in early Triassic time 41
18. Block diagram of region in late Triassic time 41
19. Block diagram of region at opening of Cenozoic era 45
20. Block diagram of region at the present time 45
21. Map showing location of interesting places 53
22. Meander scarps at edge of flood plain, Sunderland 57
23. Map of the Leverett lead veins 65
24. Diagrams showing development of Notch and Notch Mountain 74

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.

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._

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.

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.

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._

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.

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.

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.

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_