DRUMLINS 01^ CENTRAL WESTERN NEW YORK 413 



larger drumlin ridge, has 15 feet depth of till over a base of sand ; 

 but the sand substratum is restricted to the small ridge. 



In a recent extensive examination of the internal structure of 

 drumlins, to be described below, a bed of sand was found in the 

 interior mass of a drumlin, situated 2 miles northeast of Fairhaven 

 bay and south of Juniper pond. The waves of Lake Ontario have 

 dissected the drumlin obliquely, exposing a section of till about 100 

 feet high. About midway in the hight of the cliff is an irregular 

 layer of sand, 2 to 3 feet thick and of considerable but indefinite 

 extent. The sand shows no clear bedding and seems to have been 

 crushed and worked over by the ice rubbing. The extreme rarity of 

 such inclusions of water-laid drift in the drumlins of New York is a 

 conclusive argument against the theory that they are erosional 

 forms, produced by overriding and reshaping of terminal moraines. 

 This point will be discussed later. 



The drumlin till, specially in the deeper layers, is decidedly more 

 compact and harder than the ordinary sheet till, and the included 

 stones of all sizes are more generally abraded. The material gives 

 evidence of movement under pressure ; it is emphatically the glacial 

 grist. 



The proportion of crystalline and far-brought material is appar- 

 ently less than in terminal moraine deposits, but examination has 

 not been sufficiently thorough to indicate percentages. In any belt 

 it will probably be found that the proportion of material derived 

 from the subjacent strata or the rocks immediately northward is 

 larger in the drumlins than in the moraines. In other words, 

 drumlins represent, at least in central New York, the subglacial or 

 " ground moraine " drift. 



Rocdrumlins. Between Palmyra and Syracuse the foundation of 

 the drumlins is Salina shale, mostly the soft red and green beds 

 called Vernon shales. All the deeper valleys are cut in this shale, 

 which may be seen on the slopes as bare patches of bright colors, 

 red and light green. An excellent exposure may be seen at the 

 " blue cut " on the south side of the West Shore and the New York 

 Central Railroads midway between Newark and Lyons ; and at the 

 time of this writing (September 1905) the electric road building 

 in that district is making many exposures. At the "blue cut" 

 the Vernon reaches 60 feet above the railroad, or to the hight of 

 about 480 feet, judging from the map contours. In the region of 



