GEOLOGY OF MOUNT MARCY 6/ 



Local Glaciation 



The study of lateral moraines in the brook valleys, the poorly 

 developed and incipient cirques on the mountain slopes and hanging 

 tributary valleys has convinced the writer that local glaciation has 

 occurred in the Adirondacks. In 1916 Doctor Johnson demonstrated 

 to the satisfaction of the writer that such action took place after the 

 withdrawal of the continental ice sheet.^ In the cirque on the eastern 

 slope of Esther mountain, a portion of the Whiteface massif, in 

 the Lake Placid quadrangle, we found the remnant of a local moraine 

 convex down stream. This cirque valley slopes northeast offering 

 a favorable opportunity for the continental ice to force a tongue 

 into it and to deposit a recessional moraine; but this would have a 

 crest declining southwest, while that found has the opposite inclina- 

 tion. In the valley of Slide brook lateral moraines are situated on 

 both sides of the stream and appear to assume similar positions and 

 forms. 



Rich ^ has shown that local glaciers existed in the Catskills which 

 is a region less likely to support local glaciers than the Adirondacks, 

 thus lending support to the writer's contention. 



Extinct Glacial Lakes 



There are extensive sandy plains within the quadrangle that 

 undoubtedly owe their origin to the continental ice. Unless shore 

 line features and outlet channels can be found to show that they are 

 of lacustrine parentage they are regarded as outwash plains formed 

 in front of the melting ice, the debris being swept into the valleys by 

 the glacial streams. Such plains are often dimpled with ice-block 

 kettle holes in contrast to lake flats and bottoms. The great sand 

 plain of the South Meadows country, in the northwest corner of 

 the quadrangle, is an excellent example of this type of glacial deposit. 

 When first observed it was regarded as an outwash plain but rem- 

 nants of concordant beaches were found on Scotts Cobble and 

 Pitchoff mountain to question such interpretation, and thus the 

 plain is explained as a glacial lake deposit. It is quite reasonable to 

 believe, however, that it may have been an outwash plain modified 



1 Johnson, D. W., " Date of Local Glaciation in the White, Adirondack 

 and Catskill Mountains," Bui. Geol. Soc. Am. 28:543-552, 1917 



2 Rich, John L., " Notes on the Physiography and Glacial Geology of the 

 Northern Catskill Mountains," Am. Jour. Sci., 39 Iv, Feb. 1915, p. 154; 

 "Local Glaciation in the Catskill Mountains," Jour. Geol., 14:113-21, 1906; 

 " Local Glaciation in the Catskill Mountains," 29th Annual Meeting, Geol. 

 Soc. Am., paper 12, Dec. 27, 1916. Abstract Bui. 28:133, 1917. 



