MERWIN: SHORE-LINES. 319 
plain are 20 feet higher than those on the New York side warrants 
the two conclusions that uplift has been greater on the Vermont side, 
and that the line of maximum tilting slopes S. S. W. 
SHORE-LINES IN THE VALLEYS OF THE HIGHLAND OF NORTHWESTERN 
VERMONT. 
GENERAL STATEMENTS — Sections in glacial deposits of several of the 
valleys in the highlands of northwestern Vermont show beds of well- 
laminated clay scores of feet in thickness. "These are undoubtedly 
quiet water deposits. In several localities such clays are found to be 
overlain by till, or are much disturbed at the surface, as if they had 
been overridden by ice. In other localities gravels having a kame 
topography overlie clays. It seems, then, that either local or more 
widespread advances of the ice took place which must have effaced 
the shore-lines of the bodies of water in which the clays were laid 
down. For this reason only those structure sections which could be 
consistently related to existing topographic features of shore-lines 
have been given weight in the following discussion. 
From what has previously been said about the tongues of ice pushing 
eastward through the water-gaps of the Green Mountains, and from 
the topographic relations of the valleys east of the mountains, and 
also from the facts — which are discussed later — concerning the 
water-laid deposits in the valleys, the following synopsis of the devel- 
opment of drainage in the valleys during the last stages of their occu- 
pancy by ice, may give the reader a means of correlating some of the 
apparently isolated facts which are mentioned later. 
If we consider a valley already partly filled with water-laid deposits 
to be over-ridden by ice which moves up the valley, then, when the 
ice begins to retreat, a lake may form between the ice and the head 
of the valley, discharging either down the valley under or around the 
ice, or across a divide into another valley. 
In such a lake outwash from the ice might be spread in broad sand- 
plains at approximately lake-level around the tongue of the glacier 
during a period of halting. Such sand-plains might be so effective 
-a barrier as to prevent the water of the lake from falling immediately 
to a level appropriate to the next halt of the ice. If a complete barrier 
was not formed the lake would fall to its next level during the with- 
drawal of the ice. ‘Then a new outwash-plain and other shore-features 
would develop, giving the former lake basin two sets, if the water- 
