[AX] Geological Survey of Ohio, vol. iii, p. 385,
Fig. 26.—Mohegan Rock.
Portions of New England present the best illustrations anywhere afforded in America of what are called “drumlins.” These are “lenticular-shaped” hills, composed of till, and containing, interspersed through their mass, numerous scratched stones of all sizes. They vary in length from a few hundred feet to a mile, and are usually from half to two-thirds as wide as they are long. In height they vary from twenty-five to two hundred feet.
But, according to the description of Mr. Upham, whatever may be their size and height, they are singularly alike in outline and form, usually having steep sides, with gently sloping, rounded tops, and presenting a very smooth and regular contour. From this resemblance in shape to an elliptical convex lens, Professor Hitchcock has called them lenticular hills to distinguish these deposits of till from the broadly flattened or undulating sheets which are common throughout New England.
Fig. 27.—Drumlins in Goffstown, N. H. (Hitchcock).