280 THE STRtrCTUBE OF THE DAYOS VALLET. [Aug. 1 898, 



very marked difference between the whole formation of the * valley ' 

 and that of the Upper Engadine. 



The level area is occupied by a river running southward, and the 

 lake is a deep one, of very different character from the Silser and 

 Silvaplana Lakes. 



It is possible that, as Prof. Theobald held,^ the Landwasser once 

 had its source on the Rhatikon ridge, but was subsequently severed 

 from it by the back-cutting of the Landquart. There are, I believe, 

 difficulties in the way of accepting this theory, but I do not propose- 

 to discuss it at present, since such changes belong to a geological 

 period far more remote than that in which the Davos area acquired 

 its present characteristics. There can be little doubt that the 

 present great valley-systems were defined before the glacial epoch,- 

 but it seems that the present features of this district are due to 

 causes operating during and since that time. A short description of 

 the region will, it is hoped, make this clear. 



A survey of the district divides itself naturally into three sec- 

 tions : — The central level, with the lake, the upper Landwasser 

 and its tributaries; the northern ridge, forming the watershed 

 towards Klosters; and the southern outlet, where the rushing 

 waters of the Landwasser and the Sertig Bach have carved out the 

 striking Clavadel-Frauenkirch terraces. 



The central level is about 4 miles long, reaching from the 

 head of the lake to the southern end of Davos Platz. Round the 

 margin of the lake runs the contour-line of 1560 metres, and if the 

 same line is traced southward it will be found at the mouth of 

 the Sertig Thai to lie along the level of the Wildboden. In other 

 words, the flat-topped terraces so conspicuous opposite Prauenkirch 

 are on the same level as the surface of the Davoser See. 



Between these two points the river runs entirely on superficial 

 deposits. There is no spot between the lake and Prauenkirch, or 

 indeed far south towards Glaris, where the two banks of the river 

 are composed of solid rock in situ. The whole extent of the level is 

 a mass of detritus, filling in a steep-sided valley, in which the real 

 rock-floor is nowhere visible. It is true that Davos does not stand 

 on an alluvial flat in the usual sense of the term, owing to the 

 presence of great talus-fans on both sides ; but the appearance of 

 the central area is such that one finds the unscientific visitor quite 

 ready to believe in the former extension of the lake. The stretch 

 of level which produces this effect is not, however, at the head of 

 the lake, but on the side of the present outflow. 



On the western side several streams flowing from deep-cut gorges 

 have poured their burden of detritus in spreading fans over the foot 

 of the mountains. The Schiatobel, between Davos Platz and Davos 

 Dorf, forms the convex surface on which much of the new town is^ 



^ ' Naturbilder d. Rhat. Alpen ' ; see also Lubbock, ' Scenery of Switzerland,' 

 London, 1896, p. 456. 



^ The term is used in this paper merely to signify the latest time of glaciationt 

 of the district. 



