286 DENUDATION OF THE LAND. CHAP. VI. 



boulder-clay and moraine rubbish. Nor, as 

 far as I could judge, was the formation of 

 these little cliffs at all closely connected with 

 the trampling of cows or sheep. It appeared 

 as if the whole superficial, somewhat argil- 

 laceous earth, while partially held together 

 by the roots of the grasses, had slided a little 

 way down the mountain sides; and in thus 

 sliding, had yielded and cracked in horizontal 

 lines, transversely to the slope. 



Castings blown to leeward by the wind. We 

 have seen that moist castings flow, and that 

 disintegrated castings roll down any inclined 

 surface ; and we shall now see that castings, 

 recently ejected on level grass-covered 

 surfaces, are blown during gales of wind ac- 

 companied by rain to leeward. This has been 

 observed by me many times on many fields 

 during several successive years. After such 

 gales, the castings present a gently inclined 

 and smooth, or sometimes furrowed, surface 

 to windward, while they are steeply inclined 

 or precipitous to leeward, so that they resem- 

 ble on a miniature scale glacier-ground hillocks 

 of rock. They are often cavernous on the 



