GEOLOGY OF THE PARADOX LAKE QUADRANGLE 47I 



and the same distance north of Sherman Corners, is the flat bed of 

 what was probably a small glacial lake. This lake was of short 

 duration, not lasting long enough for the development of shore 

 features. It was formed by the damming of a preglacial channel 

 by the retreating ice, and its waters were supplied in part from the 

 melting edge of the ice and in part from the eastward flowing drain- 

 age of the valley. At the margin of the ice, stratified drift hills 

 were deposited which blocked the valley on the east after the ice 

 had retreated. The water speedily found a new outlet farther south 

 and the lake was drained. 



At present the stream meanders over the old lake flat, having cut 

 its channel and built a flood plain below the lake level. Its pre- 

 glacial outlet is blocked by the ridge of stratified hills, and where 

 it meets them the stream turns southward. The road to Crown 

 Point now runs through the preglacial valley, and a branch road 

 to the north has cut through one of the stratified hills, whose 

 material is now being removed for gravel. In this exposure beds 

 of coarseness varying from very fine silt to pebbles of about two 

 inches are seen, with some cross-bedding. Farther east beyond the 

 line of these hills typical boulder clay is found. 



The stream has cut a postglacial channel around the hills that 

 blocked its old valley, and after rounding them to the south it turns 

 northward again, cascading over ledges of Potsdam sandstone and 

 cutting a little canyon. The drift dam was formed at the top of a 

 steep hill, which leads downward to Lake Champlain, and the stream 

 descends this hill through a postglacial valley. After reaching 

 the lower level it turns northward and reenters its preglacial valley. 

 At the foot of the hill is another small flat which may represent 

 another temporary lake, but its complete interpretation needs investi- 

 gation beyond the limits of this quadrangle. Stratified deposits are 

 also present along the valley leading northward from this glacial 

 lake to Towner pond, these deposits being extensively eroded post- 

 glacially. Like the hills of the dam just described, these deposits 

 show great variation in size of material and often cross-bedding. 

 They were evidently formed by swift waters, and probably repre- 

 sent glacial outwash. 



