GLACIAL DRIFT. 205 



the years following scarcely any thought was bestowed upon the subject; 

 and it was almost by accident that, in 1875, I found decisive evidence to 

 prove the passage of the glacial sheet over the summit of Mt. Washing- 

 ton. Very shortly afterwards the story of the discovery was communi- 

 cated to the public, as follows, at the Detroit meeting of the American 

 Association for the Advancement of Science : 



The first suggestion of this novel proposition came to me the last clay of July, 1875, 

 from an examination of the somewhat rounded stones of small size lying along the car- 

 riage-road upon the north-east side of the mountain, about two hundred and fifty feet 

 below the summit. I stumbled upon two boulders of granitic gneiss foreign to the 

 mountain, one nearly ten and the other six inches long. This raised the altitude at 

 which transported materials existed to above 6,000 feet. Observation showed that 

 these boulders came invariably from the earth underlying the conspicuous angular de- 

 bris common all over the peak above the line of trees. In repairing the road, the 

 workmen usually dug beneath the surface blocks before obtaining a material suitable 

 for their purposes, and there always seemed to be a plenty of it. This earth proves to 

 be the ordinary grotmd moraine of modern glacialists, full of the worn angular and 

 roundish stones, which have been fashioned peculiarly by being shoved along. Large 

 boulders are not common in it, though abundant elsewhere. These stones are usually 

 of the same mica schist and gneissic rocks that compose the adjacent ledges ; and this 

 kind of ledge extends to Israel river, five or six miles distant from the top of Mt. Wash- 

 ington in a north-westerly direction. Were these deposits situated in the lowlands, 

 they would be pronounced at first sight by any one to be the common drift heaps of 

 the neighborhood. I did not discover satisfactory evidences of striation upon the few 

 stones picked up near the two boulders of granite just mentioned, but they possess the 

 characteristic shapes of those that are covered with scratches elsewhere. Some are 

 pointed at both ends, being either flattened or round along the middle. Others are 

 squarish or trapezoidal, with rounded corners. Many resemble perfectly the shapes 

 figured, by Geikie in his recent work on The Great Tee Age; and, in fact, they are 

 of the constantly occurring forms familiar to all glacialists. The rock is quite soft, and 

 that fact may explain the absence of striation. 



The question naturally arose, as I lifted up these stones. Are these the shapes result- 

 ing from the cleavage of ledges by frost? No, it could not be ; some agency of trans- 

 portation other than the falling down a slope has worn off the edges, smoothed their 

 surfaces, and mixed them with earth. The glacial ice must have transported them, 

 though they cannot have travelled more than five or six miles, or the limit of the extent 

 of this kind of rock. If this were so, then the whole of Mt. Washington was covered 

 by the glacier ice. Thus I reasoned with myself, and began to look further. Remem- 

 bering that these glaciated stones came from below the surface, I sought for localities 

 where the lower earth had been excavated. The first case examined was the founda- 

 VOL. in. 27 



