MODIFIED DRIFT ALONG ANDROSCOGGIN RIVER. I4!I 
of the river. They consist almost wholly of gravel, which is often very 
coarse, and in the highest terrace is sometimes but slightly water-worn, 
and scarcely distinguishable from till. At the sharp bend of the river, a 
mile north-west from Gorham village, three terraces occur on the east 
side, 10, 20, and 40 feet in height. The latter appears to represent the 
ancient continuous flood-plain at the close of the Champlain period. The 
village of Gorham is built on a lower terrace, 25 feet in height, which 
extends nearly level for a mile between Moose and Peabody rivers. Re- 
mains of the ancient flood-plain form terraces of coarse gravel, from 20 to 
30 feet higher, which occur on the north side of the Androscoggin oppo- 
site the mouth of Moose river, on the south side of the railroad in the 
west part of the village, and on Academy hill, which is an isolated rem- 
nant that escaped erosion because partly protected by ledges. 
Peabody river, for a mile before entering this valley, is bordered by 
steep banks of extremely coarse modified drift, or perhaps till, from 40 to 
100 feet high. The space between these banks was formerly filled with 
similar material, which has been excavated by the stream during the 
recent or terrace period. 
In Shelburne the modified drift occurs principally at two heights. The 
upper terraces are the remnants of the river’s flood-plain in the Cham- 
plain period. They are from 50 to 60 feet above the river, with a nearly 
level surface, and bordered by steep escarpments. Their material is 
usually gravel, which is frequently very coarse, but in some places it is 
mainly sand. A mile and a half east from Shelburne village, several 
small ponds occur in hollows upon this terrace plain. The lower terrace 
is interval, being only from 5 to 15 feet above the ordinary height of the 
river. 
It is a noticeable feature of the intervals of this part of the Andros- 
coggin and of the upper portion of Saco river, that they are often com- 
posed of a substratum of coarse gravel, containing pebbles one foot or 
more in diameter, above which is a layer of fine silt three to six feet 
thick forming the surface. The coarse gravel is like that which often 
forms the river’s bed in the vicinity of the mountains; and these sections, 
which are exposed in the banks now being undermined by the river, show 
that it formerly had its channel in nearly the same place as now but at 
a greater height, having flowed upon the surface of the layer of gravel, 
