Vol. 54.] THE STETJCTUfiE OF THE DAVOS VALLEY. 279 



:22. The Steijcttjee of the Davos Valley. By A. Yatjghan Jenntn^gs, 

 Esq., F.L.8., F.G.S. (Read January 5th, 1898.) 



[Abridged.] 



In several of the high Alpine passes and valleys there are certain 

 structural features which show that important changes in the process 

 of denudation have taken place, and that in many cases there has 

 been an alteration or complete reversal of the drainage-system. 



Among a considerable number of instances, that of the Upper 

 Engadine or source of the Inn is perhaps tlie most familiar. 

 Prof. Heim,-^ Prof. Bonney," and others have called attention to 

 this area as showing the way in which the gorges of the southern 

 side of the Alps are cut back with far greater steepness than the 

 river-valleys of the northern slopes. While Prof. Bonney regards 

 the difference as due to the greater rainfall and more rapid current on 

 the southern side, and the consequently greater erosive power of 

 the torrents, Dr. Preller'^ believes that it is not possible to account 

 for the present condition of the district without presupposing a 

 -subsidence on the south. Whichever view may be held, however, 

 there is no doubt as to the facts. It can hardly be disputed that 

 the Inn once took its rise beyond ITaloja, and that the glaciers on 

 the south once contributed to its formation streams now diverted 

 towards the Italian plain. The valley has in fact been decapitated, 

 and its feeding-streams have been diverted into a new and opposite 

 course. 



The object of the present paper is to call attention to the con- 

 ditions which exist in the adjacent area of Davos : conditions which 

 .are to some extent parallel, but, on the other hand, are distinctly 

 more complicated and less easy of explanation. 



Though the term ' Davos Valley ' is commonly used, it is not 

 strictly accurate, or at least conveys a wrong impression in sug- 

 gesting a similarity to the structure of the Engadine. The district 

 is an almost level area some 4 miles in length ; and the rivers 

 which flow from either end, a tributary of the Landquart on the 

 north and the Landwasser on the south, ultimately fall into the 

 Ehine near Chur. The Landwasser is fed by three principal streams 

 from the east — the Pluela, the Dischma, and the Sertig ; and just 

 below the influx of the latter it descends steeply towards Glaris and 

 the great Ziige gorge. It receives also streams from the western 

 side, and a very insignificant outflow from the deep lake which 

 occupies the northern fourth of the area. The northern outlet is 

 only by the Lareter Bach, descending from the slopes of the Todtalp 

 . and dropping through a steep cleft to Klosters. There is thus a 



"^ Heim, Schweis. Alpenclub, 1879. 



» Alpine Journal, vol. xiv, p. 221 ; aeol. Mag. 1888, p. 540. 



' Geol. Mag. 1893, p. 448. 



