Observations on the Recent Qlacial Drift of the Alps. 263 



The ground moraine here consists mainly of rounded and 

 scratched bowlders, gravel and sand, with but little clay, and only 

 a small proportion of angular blocks that cannot be traced dis- 

 tinctly to the medial or lateral moraines. The surface contour is 

 slightly, though not conspicuously, ridged. The more abrupt side 

 of these little ridges is toward the glacier and their trend is in the 

 main approximately parallel to the edge of the glacier, though 

 sometimes notably oblique. This relationship suggested that they 

 might be due to annual oscillations of the glacial margin. There 

 is also discernable a feeble tendency of the material to arrange 

 itself in heaps and ridges parallel to the lines of movement of the 

 ice. 



3. If we now approach the foot of the glacier, we shall fiad this 

 moranic sheet of detritus passing without notable change or inter- 

 ruption beneath the ice. The appearance is as though a stationary 

 mass of ice had formed on the surface of a bed of bowlders and 

 gravel and was now quietly melting away. More critical exam- 

 ination would, of course, show that any given particle of ice was 

 advancing. The edge of the glacier is thin and sloping and we 

 may walk directly up on it. The edge seems to rest lightly upon 

 the drift below. This last is not a mass of debris frozen together, 

 or imbedded in the base of the ice — although individual bowlders 

 are — but an independent underlying bed of bowlders, and finer 

 material and open interspaces. These observations of course re- 

 late to the immediate edge of the ice. Some of the crevasses enable 

 us to see a short distance farther io, where the same condition pre- 

 vails. An artificial tunnel, styled an ice grotto, shows the same 

 through a break in the ice. 



The marginal portion of the glacier rests, so far as could be 

 ascertained, not upon the bed rock, but upon its own basal mo- 

 raine. How thick this bottom accumulation was, I had no means 

 of ascertaining, but from the configuration of the valley, I should 

 judge it was considerable. 



4. The surface contour of the ground moraine seems to some 

 extent to take shape beneath the glacier. At one point I observed 

 a diminutive hillock, about six feet high, half enclosed in the edge 

 of the ice, which was here nearly vertical. The appearance was 



