Scientific Intelligence — Geology. 377 



the sides of the galleries, as these are much affected by the air 

 circulating in the vicinity, which, also, being itself exposed to so 

 many disturbing causes, cannot be regarded as giving more than 

 a very distant approximation to the real temperature of a given 

 spot. — W. J, Henwood^ Esq. in Records of Science^ Sept. 1836. 

 15. The Uniformity of t/te Form of Mountain Slopes in the 

 Higher Alps, with an attempt to explain the facts., and an ex- 

 position of the resulting consequences. — Everywhere, at the 

 height of about 5000 feet above the level of the sea, in that line 

 in which in the Alps the region [of forests terminates, and gives 

 place to that of pasturage, there appear, as if by enchantment, 

 great smiling plains of about a mile broad, and sometimes man}^ 

 leagues long, which are bounded by vertical walls of rocks, 

 by fields of snow, or by slopes covered with debris, or rolled 

 pebbles. On the contrary, if we descend lower, to the region 

 where the forests cover the soil, there we everywhere find rapid 

 declivities, cut into the shape of gorges and of funnels. This 

 constant difference in the form of the slopes is owing to the differ- 

 ence of the vegetation by which they are covered. In those re- 

 gions where the forests exist, not only do their roots protect the 

 rapid declivities of the rocks from the action of atmospheric in- 

 fluences, but their trunks also arrest the descent of the debris 

 which fall from the more elevated rocks. These debris in the 

 long run undergo a change, and are converted into vegetable 

 mould, which is ever making an addition to the soil which co- 

 vers the rock. Under these circumstances the valley which the 

 mountain forms continues to be straight, having all the characters 

 of a narrow defile. On the contrary, in those places in which 

 the forests are wanting, the sides of the mountains being freely 

 exposed to all the vicissitudes of the weather, are unceasingly 

 undergoing the process of decomposition, the bottom of the 

 valley is gradually filled up with the debris which are constantly 

 descending, whilst the lateral slopes are ever gradually receding 

 from each other. Attentive observation, continued for several 

 successive years, and directed to the decomposifion and rolling 

 down of the slopes which are not protected by forests, would 

 supply the data for an approximate calculation of the length of 

 time which would be necessary for the formation of the entire 

 valley. From these considerations we may at once perceive how 



