Erratics of the Alps. 



287 



limestone rock (L in the small section, figure 1 below) is washed at 

 the foot by the Aar (r), which it overhangs, and the surface on which 

 the blocks (6) rest is extremely steep. To the upper ones* about 

 300 feet above the river, I could only ascend by using both hands 

 and feet. Some of them contained one Or two cubic yards of stone, 

 and were in situations from which a slight force would precipitate 

 them to the bottom. I was agreeably surprised, for I did not ex- 

 pect to meet with facts illustrative of the erratic formation so easily. 

 The granite blocks came from q, or some place within the boundary 

 line I m n — that is, they had travelled twenty miles or more. In 

 this simple fact I had presumptive evidence that the agents which 

 transported them were not currents of water; for currents strong 

 enough to bring them hither would not have left them on a steep 

 ledge of rock from which a slight impulse would detach them. 



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At b in the map, on the south side of the lake, near the village of 

 Bonigen, there is a projecting mass of a conical form, which leans 

 against the mountain, as if it were an outer portion of the rocks 

 above, which, having lost its hold, had slid downward, and in sliding 

 downward had been pushed outward. The hollow above it has some 

 resemblance to a corry. This semi-cone is 600 or 700 feet in 

 height; its base projects perhaps 1000 feet from the side of the 

 mountain, and its circumference may be nearly a mile. Three de- 

 pressions like terraces, one above another, are seen on its surface, 

 which is everywhere covered with clay, earth, or gravel, though there 

 is in all probability a nucleus of displaced rock below. Figure 2 

 above, is a section of the lowest of the three terraces ; B, the lake of 

 Brienz ; L, the limestone of the hill, assumed to be the nucleus of 

 the cone ; 6, blocks resting at various heights on its surface. Ascend- 

 ing by the east side, I met with a block of granite 3 yards long, 3 

 broad, and 1} yards thick, measuring of course about 10 cubic yards, 

 and weighing twenty tons. It was resting on the soil, 120 feet 

 above the plain, on the side of a declivity dipping at 50° or 60° 

 — so steep, indeed, that if it had fallen even from a height of 

 3 feet, it would infallibly have slid or rolled to the bottom. It had 

 travelled 20 or 30 miles, but the agent which transported it must 

 have set it down as cautiously as a nurse deposits a sleeping child in 

 its cradle. Its position suggests the idea either that it must have 

 been stranded here by floating ice, or that it and the soil under it 



U2 



