PLEISTOCENE GEOLOGY OF MOOERS QUADRANGLE 25 



district almost entirely in road and railway cuttings, but many 

 along these lines of travel are also natural exposures, particularly 

 in the zone of wave action. 



The natural exposures are mainly due to the sweeping away of 

 the drift and beach materials along the beds and banks of streams, 

 and in the low grounds from elevations of 600 feet downward, to 

 the scouring action of waves. Their distribution serves to show 

 that over most of the area the covering of glacial deposits and the 

 wave-modified drift derived from them are on the whole thin. 

 Where these small exposures are crowded, the surficial deposits 

 are thinner than in regions where the outcrops are widely 

 scattered. 



LATE AND POST-WISCONSIN LAKE AND MARINE DEPOSITS 



The complicated course of events attending the disappearance 

 of the ice sheet from the northern slope of the Adirondacks can 

 perhaps be understood if it is remembered that, while the tor- 

 rents which produced the spillways were discharging along the 

 ice front over the district from the south side of Covey hill to 

 the Little Chazy, the ice sheet was gradually receding from this 

 position, that over the site of Lake Champlain a glacial lake 

 was expanding northward foot by foot with the recession of 

 the ice front, and that standing water crept in between the ice 

 front and the eastern margin of the flat rock areas. As the 

 ice still further withdrew, an open lake existed for a time with 

 an ice barrier for its northern shore, stretching in an ill defined 

 line from Covey hill to the northern versant of the Green moun- 

 tains. It was still the Wisconsin glacial epoch. The ice next 

 disappeared from the entrance to Lake Champlain, and the sea 

 came in and began a new series of processes. The Wisconsin 

 epoch locally had closed, and a new epoch with essentially non- 

 glacial processes of change had been introduced. This epoch 

 is the only true " Champlain " epoch of the Pleistocene period. 

 The sea did not apparently stand as high against the land as 

 did the earlier lake shores. The beaches of both series are 

 preserved on the Mooers quadrangle, and it is difficult to (lis 

 tinguish between them as one traverses the wave-modified belt 

 from the lowlands near Lake Champlain to the upper limit of 



