30 NEW YORK STATE MUSEUM 



Seneca, Keuka, Canandaigua, Canadice, Conesus and Hemlock. These 

 lakes are all of glacial origin, being the drainage valleys of a preglacial 

 river system. At the close of the ice age their outlets to the north were 

 blocked by extensive deposits of drift dropped by the retreating glacier, 

 causing the general line of lakes with their outlet system to assume a 

 direction parallel with the margin of the great Ontario lobe of the ice sheet, 

 the lake valleys running radially to the edge of the ice lobe and extending 

 mostly in a north and south direction. With the exception of the three 

 westernmost lakes of the chain, they drain through the Canandaigua- 

 Seneca-Oneida-Oswego system into Lake Ontario. Thus, the country under 

 consideration is practically the basin of the Oswego river. The lakes 

 lie at altitudes ranging from 364 feet to over 700 feet in the case of the 

 smaller southern and western members of the chain. The northern and 

 eastern portions of this country average about 500 feet in elevation. 

 About the southern ends, after Oneida and Onondaga are passed, lie the 

 hills which mark the northern slopes of the Alleghanian plateau. Many of 

 these hills surpass 2000 feet in elevation. This lake country is well settled, 

 and extensive forests are nowhere in evidence except in the larger swamps 

 and on the more elevated hills. Characteristic trees are the beech, maple, 

 elm, ash, basswood, sycamore, oaks, chestnut, sassafras, hornbeams, shad 

 tree, flowering dogwood, thorn trees, white pine, pitch pine and red cedar. 

 Arbor vitae and tamarack swamps are of frequent occurrence. In the 

 gullies, hemlock, yellow birch, mountain maple and striped maple are 

 common, especially on the shaded slopes. There are numerous deep-cut 

 ravines in the shaly rock of the Hamilton and Chemung periods, well 

 typified by the famous Watkins glen. Their prevailing east and west 

 direction causes the southern sides to lie mostly in shade, and at the same 

 time percolating waters from the outcropping strata on the sides of the 

 glen, and the tumbling waters of the glen streams, cause a high moisture 

 content in the glen atmosphere. Consequently, there is both a lower tem- 

 perature in the glen and a slower rate of evaporation from the surface of 



