BANDED CLAYS. 25 
the Ammonoosuc Valley. No contorted zones were noted at this Lisbon 
locality. 
An important generalization must be made at this point. The clays 
were not everywhere deposited across the valley continuously in all places. 
On one side of the valley fine clays may be present while on the opposite shore 
sands and even gravels may be found. In order to understand this difference 
in deposition the conditions in the valley at the time of the withdrawal of the 
ice from this region must be clearly understood. 
It is clear that the Connecticut Valley was a lake. The waters of the 
lake were probably held up on the north by the retreating glacier. On account 
of depression in the region described and in the St. Lawrence Valley to the north, 
the waters from the melting ice, instead of flowing rapidly away towards the 
south, in a glacial torrent, as they would do under the present conditions, were 
ponded back against the ice front, but forced, nevertheless, to flow southward 
on account of the lack of an outlet to the country under the ice to the north. 
Even as far south as Northampton, Massachusetts, the country was much 
lower than it is today, as proved by the glacial clays in that region. 
Regarding this region Emerson, 1917, writes: 
“As the basin of the Connecticut became free of ice a body of water was formed so 
broad and deep that laminated clays were deposited in it 180 feet deep, so long lived that it 
has cut deep notches and developed broad deltas at its shore line, and so slow in current 
that the thin-layered clays were formed even through the narrows between its broader water 
bodies. These narrows divide the lake into the small Montague Lake; the long Hadley 
Lake, north and west of the Holyoke Range, extending from Greenfield south past Northamp- 
ton into Connecticut; and south of the same range the Springfield Lake, 20 miles broad, 
reaching far south to the middle of Connecticut. The ice front still retreated northwest 
across the Berkshire Hills, with great lobes extending down the valleys and out into these 
lakes, where they calved icebergs, thrust the clays up in extreme confusion, and maintained 
an Arctic climate during all the life of the lake. 
“The lakes are bordered by a bench, which is well marked where it cuts into sand beds 
or drumlins and broadens in great delta flats at the mouth of tributary valleys. Its gravels 
grade through sands into the laminated clays of the lake bottom. Each stratum is double. 
Its lower half is composed of very fine sand, which grades up into a much finer blue clay, and 
the change is abrupt from the top of this layer of blue clay to the bottom of the next sandy 
layer. In places a film of coarser sand, an incipient ripple marking, a mica scale, or fossil 
leaves appear at the top of the layer of clay. 
“The sandy layer represents the flood waters of the opening spring and grades into the 
fat clay that settled from the stagnant water beneath the ice of the following winter. Each 
layer thus represents a year’s growth. As the clays are about 180 feet deep and each layer 
about one-third of an inch thick, the lake may have remained about 6,000 years. 
“The bench stands about 400 feet above the present sea level at the north line of the 
State and 200 feet above it at the south line. As there was almost no southward current in 
