RECENT CONTRIBUTIONS TO THE GEOLOGY 

 OF THE WESTERN ALPS. 



A LARGE scale geological map is usually recognised 

 as occupying the same position in the geological 

 study of a country as a trigonometrical survey does in its 

 geography ; but it is much less often realised. In moun- 

 tainous countries it is an ideal at which it is especially 

 necessary to aim, and which is especially difficult of attain- 

 ment. In regions like the Alps, where much of the ground 

 is covered by snow and ice, by forest and debris, where 

 artificial sections or the plough do not come to the aid of 

 the geologist, and where unscaleable cliffs bar his approach 

 to many of the finest sections, a complete map is often 

 impracticable. Moreover, the geological interpretation of 

 the structure of a country may be at any time modified by 

 the raising of the snow line after a dry, hot summer, 

 whereby rocks are exposed to view which have not been 

 seen for decades, and will, on the first winter's snow, be 

 covered for decades again. Professor Bonney has clearly 

 pointed out the reasons why a detailed, petrographical map 

 of the Alps of Switzerland will be long delayed, 1 even if the 

 difficulties be finally overcome at last. And in- the Western 

 Alps of Northern Italy lack of accommodation and the 

 suspicions of the frontier guard place further obstacles in 

 the way. 



It is therefore not surprising that in the study of the 

 geology of the Alps hypothesis and speculation have been 

 more than usually rampant. Nor is it strange that anti- 

 quated theories and unscientific notions still linger amid 

 these mountain fastnesses, with the ghosts and goblins that 

 survive in the minds of the superstitious peasants of the 

 upland chalets. This is especially the case in the Western 

 Alps, which, in addition to the previously mentioned 

 difficulties, have special ones of their own. The Central 



1 Quart. Jour ?i. Geo/. Soc, vol. xlvi., pp. 187-188, 1890. 



II 



