18 W. UPHAM — DRUMLINS AND MARGINAL MORAINES. 



granites, gneisses or quartzose schists, is made up principally of exceed- 

 ingly finely comminuted quartz particles. 



Likewise the marginal moraines, which record the history and work 

 of the ice-sheets during the fluctuating stages of their wavering final re- 

 cession, are, along the greater part of their extent, composed mainly of 

 till, with multitudes of boulders. Nearly everywhere also they inclose 

 occasional lenticular or irregular beds of gravel and sand, with here and 

 there superficial knolls and short ridges of similar gravel and sand, called 

 kames. The inner stratified beds and the kames were laid down by 

 streams from the ice melting and from rains, while the till of the moraines 

 was borne and pushed forward by the slowly advancing ice to the limit 

 where the equilibrium of climatic conditions temporarily held the glacial 

 border nearly stationary during any series of years. Less frequently 

 some considerable extent of the marginal drift belt, though amassed in 

 hills 100 to 200 feet high, consists almost wholly of modified drift, being 

 stratified gravel and sand, with only rare inclosed or superficial boulders, 

 forming a prolonged series of gigantic, massively rounded kame deposits, 

 as in the great frontal moraine on Long island, from Roslj^n east to Na- 

 peague, a distance of about 75 miles. 



The purpose of the present paper is to inquire how the ice amassed its 

 prominent, round or oval, and sometimes more elongated, hills of till 

 called drumlins, and how it brought and heaped up the till in its equally 

 conspicuous, but more confusedl}^ grouped, marginalmoraine hills, dis- 

 tinguished notably by their irregularity of contour, abundant boulders 

 and extension in series which are traced hundreds and even thousands 

 of miles, from Nantucket, Marthas Vineyard and cape Cod to Wisconsin 

 Iowa, Minnesota, South and North Dakota, Manitoba and the northwest- 

 ern plains of Assiniboia, Saskatchewan, and Alberta. Both tlie drundins 

 and the moraines are found referable to the Champlain e[)och or closing 

 part of the Glacial period, when the country, heavily laden by the ice- 

 sheet, had sunk from its high pregiacial and Glacial elevation, being de- 

 pressed mostly somewhat below its present height, so that the reign of 

 the Arctic climate, which had dee])ly covered the land with snow and 

 ice, was rapidly brought to an end by mild tem})erate conditions nearly 

 like those of the present time in the same latitudes. 



For Europe, as well as North America, the drumlins and moraines are 

 shown to be referable to this final Champlain epoch of the Ice age ; and 

 the whole history of the Glacial period, in its beginning, successive stages, 

 and end, appears to have been, in a general way, S3nichronous througliout 

 its series of stages on the two continents. During the growth and culmina- 

 tion of the ice-sheets in both North America and Europe the conditions 

 of glacial action in transportation and deposition of drift were very un- 



