6-4 NEW YORK STATE MUSEUM 



over the major part of the State, reaching as far south as New York 

 City. In order to provide a sufficient gradient for such an expanse 

 of ice the surface of the ice that moved over the quadrangle has 

 been estimated to have been from 8500 to 12,000 feet above sea 

 level.-^ To this enormous load upon the land surface is attributed 

 the well observed phenomenon of deformation, to which we shall 

 return later. 



Movement 



Two occurrences of glacial striae have been noted in the quad- 

 rangle; they are situated beside the highways in the valley of the 

 East branch of the Ausable river. The direction of both of these 

 striae is due south, indicating that the topography was the controlling 

 influence affecting the course taken by the waning ice lobes lying in 

 the valleys. The more general direction of the ice flow would be 

 shown by striae on the mountain summits, but their records have 

 been destroyed by weathering. It is believed, however, that the ice 

 that covered the quadrangle flowed southward with a slight deviation 

 to the west. 



Erosional Work 



The residual soil resulting from weathering during interglacial 

 periods was completely removed by the ice, the mountains smoothed 

 and their contours subdued. This effect of ice action is recorded 

 in the comparatively fresh condition of the rocks on exposed ledges, 

 and in the dignity of the round dome of Marcy probably due to 

 glacial erosion. 



The many amphitheaters and little rocky pockets on the mountain 

 sides are due, in all probability, to the plucking action of the ice. 

 These cirques have been attributed to the combined work of the 

 continental ice bodies and to local glaciers.^ "An amphitheatre with 

 steep walls ... is a favorite form for the Adirondacks, being 

 well shown on . . . the Gothics," ^ the Cascade- Porter massif. 

 Big Slide, Haystack and Noonmark. Occasionally small ponds are 

 located on the southern or lee side of the mountains, apparently 

 occupying basins plucked out by the ice. Lost pond in the south- 

 western corner of the Ausable sheet, the pond on Clements moun- 

 tain in the quadrangle to the north, and the Giant Washbowl and 

 Dipper are examples. 



1 Fairchild, H. L. Bui. Geol. Soc. Am., 24:136. 1913. After Shackleton. 



2 Ogilvie, I. H., " Glacial Phenomena in the Adirondacks," Jour. Geol., 

 10 :4o6. 1902. Johnson, D. W., " Date of Local Glaciation in the White, 

 Adirondack, and Catskill Mountains," Bui. Geol. Soc. Am. 



Mvemp, J. F., N. Y. State Mus. Bui. 21, p. 63. 189S. 



