164 ROCHESTER ACADEMY OF SCIENCE. 



were advanced to account for them. By some they were explained 

 as ancient sea shores (Hisinger, Martins (69), Chambers (15), 

 Erdman (33), Torell, etc.). Ramsay refers to them as "those 

 marine gravelly mounds, called kames or eskers" (78). Another 

 idea was that a "vast deposit of sand and mud covering the country 

 which had been cut thru by rivers, whose beds were gradually filled 

 Avith stones and gravel. Later the sand and mud were washed away, 

 leaving the stone and gravel deposits of the rivers in the shape of 

 ridges" (109). They were also regarded as being due to a great 

 diluvial flood (91). Again they were thought to have been formed 

 by marine currents during the submergence of the land (117). 

 Another very early idea compared them to the submarine banks 

 formed in the pathway of tidal currents near the shore. Under the 

 old idea of the aqueous origin of the drift they were referred to 

 iceberg action (73). Jamieson explained both kames and eskers as 

 moraines of gravelly debris deposited at the edge of an oscillating 

 icesheet ; the ridge-like form he considered due partially to the ice 

 on its advance pushing the material before it (58). In certain 

 localities in this country they are popularly believed to represent the 

 work of the aborigines, hence the name "Indian roads" applied to 

 them. 



Hummel of the Geological Survey of Sweden seems to have 

 been the first one to recognize the fact that the existence of an inland 

 ice sheet must be presupposed as the indisi)ensable agent in forming 

 such ridges. He regarded them as being formed beneath the ice in 

 tunnels excavated by percolating waters (1874) (57). In 1876 Hoist, 

 another Scandinavian, published his theory of their origin in the 

 beds of supra-glacial rivers (56). The same view was advocated by 

 Upham in 1878 in this country (115,117). Dana regarded eskers 

 as being subglacial moraines. The idea of glacio-fluvial origin of 

 this type of glacial phenomena has long been entertained, and there 

 is general agreement on this point by all glacialists. 



Geologists in this country who have made notable contributions 

 to the subject are N. H. Winchell, I. C. Russell, Warren Upham, 

 G. H. Stone, W. O. Crosby, T. C. Chamberlin, R. D. Salisbury, 

 W. M. Davis, Frank Leverett and J. B. Woodworth. 



Occurrence of Eskers. General Occurrence. Eskers occur 

 only in glaciated regions and are limited to areas that were covered 



