BULLETIN OF THE GEOLOGICAL SOCIETY OF AMERICA 

 Vol. 7, pp. 17-30 November i4, 1895 



DRUMLINS AND MARGINAL MORAINES OF ICE-SHEETS 



BY WARREN UPHAM 



{Presented before the Society August 28, 1895) 



CONTENTS 



Page 



Introduction 17 



North American areas of drumlins 19 



Accumulation of drumlins from englacial drift 21 



North American marginal moraines 23 



Conditions of formation of marginal moraines 24 



Drumlins and moraines both referable chiefly to the Champlain epoch 26 



European drumlins and moraines 27 



Recognition of the Champlain epoch in Europe 28 



Contrast of the growth and decline of the Pleistocene ice-sheets in their depo- 

 sition of drift 28 



Comparison of present ice action in Alaska and Greenland 29 



Introduction. 



The chief characteristic of the present stage of investigations of the 

 Ice age and its glacial and modified drift deposits seems to consist in the 

 search, through observations and study, for explanations of the methods 

 in which the ice-sheets of North America, northern Europe, Patagonia, 

 and other glaciated areas, acted in eroding, mingling, transporting and 

 depositing the various drift formations. 



All the diverse phases of the till or ground moraine, also called boulder- 

 clay, from its heterogeneous materials, and including much englacial 

 drift, which was allowed to fall loosely on the ground from the ice dur- 

 ing its stages of retreat, are classed together as direct products of the 

 action of land ice, without modification by the assorting, transporting 

 and stratifying agency of streams and lakes formed by the glacial melt- 

 ing and accompanying rains. Most drumlins in their entire mass, and 

 all others in their superficial part, consist of till, an unstratified deposit 

 of intermingled boulders, gravel, sand and clay, in which usually the 

 largest ingredient by measure is the very finely ground rock flour of the 

 glacial grist. Though called clay, the rock flour, on areas of sandstone, 



III— BuLi,. Geol, Soc. Am., Vol. 7, 1895. ■ (17) 



