340 



HISTORICAL GEOLOGY 



conditions, as perhaps along longitudinal crevasses or fissures. 

 Two of the finest and most extensive exhibitions of drumlins in 

 the world are in New York, between Syracuse and Rochester, 

 and in eastern Wisconsin, where thousands of them rise above the 

 general l Q vel of the plains and give rise to a unique topography. 



Another type of glacial deposit in the low hill form is the kame, 

 which, in contrast with the drumlin, always consists of stratified 

 drift. Karnes are seldom as much as 200 feet high, and typically 

 they have nearly circular bases, though frequently they are of 



Fig. 214 



A group of kames in New York state. (From Norton's " Elements 



of Geology," by permission of Ginn and Company, Publishers.) 



very irregular shapes. At times they exist as isolated hills or in 

 small groups (Fig. 214), while often they are associated with the 

 unstratified deposits of the moraines. When grouped, deep depres- 

 sions occur between the hills to form what is called the knob and 

 kettle structure. Kames were formed at or near the margin of the 

 retreating ice, and so are found in all parts of the glaciated area, 

 but more especially where there is considerable relief, as in New 

 York and New England. They most generally are located in vahW 

 bottoms, but sometimes on hillsides or even hilltops. They are 

 especially abundant along the line of the great terminal moraine 

 (e.g. Long Island) and along the fines of the more important 

 recessional moraines. They were formed as deposits by debris- 

 laden streams emerging from the margin of the ice, the water 



