Acoiiii nltifioit of Di'K mlliiK. — rphani. '341 
capped by the rounded niiiss of till for tlie iipi)er half of the 
hill. 
Again, lenticulai- slopes of till, iiaviug the same smoothly flow- 
ing outlines as the drumlius, are sometimes accumulated on the 
lee side of hills of rock; the hill and the detritus sheltered Ixdiind 
it being known as '-crag and tail.'' A large numlier of such 
slopes were mapped by Ww writer in 1878 in New Hampshire, 
besides about half as many similar slopes of till lying upon the 
northern sides of rock hills, where they were most fully exposed 
to the ice-current. The knobs of rock in each case may be said 
to have combed the drift from the ice by which it was being borne 
forward. More rarely the slopes wx^re gathered upon both north and 
south sides alike, lilending together and assuming the form of a 
drumlin, but having outcrops of rock at the top. In Massachu- 
setts, however, though almost equally a region of pU'ntiful rock 
hills, Mr. (jreorge H. IJarton, in mapping the drumlins. finds very 
few of these till slopes. 
Most instructive variations from the usual constitution of the 
drumlins are presented where anticlinally stratified beds of gravel, 
sand, and clay or fine silt, form their inner part, reaching in a 
dome-shaped accumulation from the Itase upward to comprise 
sometimes the greater part of the section, with a deposit of till, 
which may be from a few feet to 25 feet or more in thickness, 
spread over these beds so as to form the entire surface. Among 
many sections of drumlins observed by me in New England, the 
only examples of this structure are Thir<l and Fourth Clitl's, par- 
tially eroded drumlins in Scituate, Mass., on the shore of Massa- 
chusetts l)ay.* These rounded, low hills, rising respectively about 
7(1 and (iO feet above the sea, consist of till upon their whole sur- 
face and to a depth that varies from 15 to 25 feet and nioi'e, but 
below include beds of modified drift that attain in Third (Mitf a 
thickness of at least HO to -tO feet, reaching to the boulder-strewn 
shore, and in Fourth (Mitf a thickness of 1<I to 20 feet, being 
seen there to be underlain by til! and to boalso in part interbedded 
with it. 
In Madison. Wisconsin, and its vicinity, dnindins Juiving thus 
an anticlinal nucleus of modified drift and surface of till are 
more frequent, as I am informed by Prof. T. C. ('liaml)erlin and 
■"'I'l-oceedings of the boston Society of Nntnral 1 1 islory. N"ol. w i v. 
pp. 2L'f^-24"J, with niaf) and sections; April 17, iSS!'. 
