18 SEASONAL DEPOSITION IN AQUEO-GLACIAL SEDIMENTS. 
crosses the Ammonoosuc River, is the brick-yard and clay-pit of E. M. Lamarre. 
The bottom of the clay at its contact with the underlying till is, by aneroid, 
twenty-eight feet above the Connecticut River. The actual contact is not, 
at present, visible, but till outcrops about 100 feet to the north, and the present 
bottom of the clay-pit is estimated to be about seven feet above the top of 
this till horizon. There are so many characters in this Woodsville locality 
which resemble those found in the slate at Squantum that a careful description 
will be given. 
As remarked above, there are about seven feet of clay under the present 
bottom of the lowest part of the pit. The first layers visible at the bottom 
average one fourth of an inch in thickness and this width of the annual deposits 
among the first few feet is repeated with an extremely even interval. This first 
group of bands is four feet six inches thick (Fig. 1, 1, no. 1).1_ Near the top, 
the layers increase to one half inch in thickness. At this point there appears 
a layer of rock-flour mixed with pebbles which resembles till. This material 
appears to have dropped from floating ice, whether ice of an advancing glacier 
or of a large berg it is not possible to say. The thickening annual deposits 
just below might indicate an advancing glacier. The lack of contortions in 
this till layer and in the lower deposits and the even upper surface of the till 
layer prove that the water at this point was deep enough to float the ice above 
it. On the till deposit is a layer of rock-flour ten inches thick (No. 2). This 
would appear to indicate a retreat of the glacier and that when this rock-flour 
was deposited, the glacial stream was not far off, for without a near supply of 
material, such a thick deposit of the rock-flour could not have been laid down, 
in what appears to be a single year. Above the rock-flour come six inches of 
annual deposits averaging one half inch each (No. 4). Above these again 
appears a deposit of rock-flour (No. 5) nine inches thick. Either the glacier 
advanced again or the glacial stream shifted so as to bring once more a thicker 
deposit. That stream action was the agent in the deposition of this rock-flour 
deposit is indicated by a gravel layer two inches thick (No. 6) resting on the 
rock-flour. This gravel is composed of well-sorted pebbles which have been 
scarcely water worn at all. They are mostly angular fragments of small size, 
very few being over one fourth of an inch in diameter. Annual deposits rest 
on this gravel layer to a thickness of fourteen inches (No. 7) with thicknesses 
averaging three fourths of an inch each. -Such thick annual deposits, of such 
very fine material, three times as thick as the lowest ones below, might indicate 
1See also Plate 1. 
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