PLEISTOCENE GEOLOGY OF MOOERS QUADRANGLE 55 



the northern margin of the Mooers quadrangle at about 450 feet 

 and on the southern margin of the area at about 370 feet. 



Such a tilted plane agrees very closely with the rate of falling 

 off in elevation of the fossil shell localities from Montreal to 

 the southernmost localities known on the New York shore of 

 Lake Champlain. 



The land in this district was at an undeterminable elevation 

 during the time it was ice covered. When the ice began to 

 disappear from the region a glacial lake formed along its front 

 in the Champlain valley and it is evident that the land in the 

 southern part of the State was higher than it is now in relation 

 to the Champlain district. During the existence of this glacial 

 lake, changes of level apparently were in progress, but they can 

 not well be discussed without more detailed reference to the glacial 

 retreat on the south than can be given in this local report. 



After the sea came in from the north, the land at least began 

 or perhaps continued to rise gradually, causing the sea to 

 retreat from the area. As the land rose, the streams extended 

 their courses, building noticeable deltas at particular levels; 

 and gradually the existing state of physical features of the area 

 was established. There are some reasons for believing that the 

 changes of level are still in progress, though no local measure- 

 ment of such a movement has been detected. 



The general discussion and a more complete account of the 

 glacial lakes and the marine submergence in this area and 

 throughout the Hudson and Champlain valleys will be found 

 in Museum Bulletin 84. 



EXPLANATION OF THE MAP OF THE MOOERS QUADRANGLE 



The southwestern part of the Mooers quadrangle everywhere 

 above the elevation of 900 feet, and in many places from about 

 700 feet upward is more or less thickly coated with typical till, 

 here and there taking on a hummocky aspect where thickened 

 in the manner indicative of recessional moraines. There is but 

 one stratified sand deposit in this field, that near Alder Bend. 



The mapping of the general sheet of surficial deposits below 

 the limits of this clearly demonstrable unmodified glacial drift 

 must be regarded as provisional. After the work was begun 



