GEOLOGY OF THE SCHROON LAKE QUADRANGLE 85 



1 6 S 15 E. On Marcy anorthosite near the creek three- fourths 

 of a mile northeast of Boreas river. 



17, 1 8, 19, 20 S 10 E. Four records on Marcy anorthosite by 

 the road between I and 1^4 miles east-northeast of Boreas river. 



It will be seen from this list that the extreme range in direction 

 of the glacial striae is from S 15 E to S 30 W. Further, all but 

 two sets of the striae run from N-S to S 15 E. It is evident, 

 therefore, that the general direction of movement of the ice over 

 the quadrangle, except possibly its northeastern one-fourth where 

 no striae were observed, was a little to the east of south. This 

 harmonizes closely with the sixty sets of glacial striae observed by 

 the writer 1 in the North Creek quadrangle next to the south, the 

 average direction of which is almost exactly N-S. 



Regarding the Paradox Lake quadrangle which lies just east, 

 Doctor Ogilvie says : 2 ' The more southerly and easterly parts of 

 the quadrangle were in the region of the southwesterly moving ice 

 current.'' Professor Kemp 3 has reached a similar conclusion 

 regarding the southeastern portion of the Elizabethtown quad- 

 rangle, and further observations there by the writer reinforce this 

 view. In the Blue Mountain quadrangle, the second to the west of 

 the Schroon Lake quadrangle, the writer 4 has recently shown that 

 the general direction of ice movement was southwestward. Pro- 

 fessor Gushing 5 reached the same conclusion regarding the Long 

 Lake quadrangle. As shown by the writer, 6 the general ice cur- 

 rent was southwestward across the Lake Pleasant quadrangle in 

 the south-central Adirondacks. 



From the above facts it is evident that the southward to even 

 slightly southeastward movement of the ice across the Schroon 

 Lake and North Creek quadrangles was rather strikingly excep- 

 tional, having been surrounded by the great sheet of generally 

 southwestward moving ice. The writer has no explanation for this 

 puzzling fact. Local topographic control of the ice current in the 

 Schroon Lake area can not have been the cause of the deflection 

 because most of the prominent ridges and valleys have a north- 

 northeasterly strike and the others vary from east-west to north- 

 west, so that the ice moved across these sets of valleys at angles of 

 from 20 to 90 degrees. The location and strike of striae in valleys, 



*N. Y. State Mus. Bui. 170, p. 66. 1914. 



2 N. Y. State Mus. Bui. 96, p. 470. 1905. 



3 N. Y. State Mus. Bui. 138, p. 95. 1910. 



* N. Y. State Mus. Bui. 192, p. 48. 1916. 

 8 N. Y. State Mus. Bui. 115, p. 495. 1907. 



N. Y. State Mus. Bui. 182, p. 63-64. 1916. 



