264 A. V. Jennings — The Landwasser and Landquart. 



Again, a study of the geological map may suggest that the rapid 

 back-cutting of the Landquart was due to the more rapid erosion 

 of the grey Biindner Schiefer of the Pratigau, in comparison with 

 that of the crystalline rocks, limestones, etc., which formed the bed 

 of the ' Landwasser.' The grey Biindner Schiefer, however, lay only 

 at the base of the ridge, and it is the through-cutting of the ridge 

 itself that is the difBculty. It was only after the cutting of the 

 ridge that the Landquart would in the critical area have arrived at 

 the underlying shales, and this brings us to a consideration of the 

 nature of the ridge itself. 



Although the district is a difficult one, owing to its being the 

 point at which the simple outcrop-line of stratified works running 

 south-east to Klosters fi-om the Scesaplana district passes into the 

 complex folds traceable near Davos, yet a study of the present 

 outcrops of the various formations gives us a fairly accurate idea of 

 what must have been the structure. Its most conspicuous feature 

 was doubtless the band of ' Hauptdolomit ' now seen to form the 

 Casanna on the south of the Pratigau and the Calanda on the 

 north. A line drawn from the present top of the former, doubtless 

 then considerably higher, to the upper limit of limestone on the latter 

 gives a height above the sea of 2,650 metres. This would be about 

 4,800 feet above the present level of Klosters, and 2,800 feet 

 above the Drusatch Alp. The limestone series was accompanied by 

 a gi'eater or less thickness of Verrucano and Casanna Schiefer, with 

 probably a band of serpentine ; and the whole series was thrust 

 over the grey Biindner Schiefer, which dipped south and east 

 below it. Above the limestone and its associated rocks there was 

 in all probability a capping of the schists and gneisses belonging 

 to the older crystalline series, such as now overlie it to a vast 

 thickness on the Eastern Ehatikon, and still remain to form the 

 peak of the Madrishorn. What may have been the thickness of this 

 crystalline covering it is impossible to say. Even, however, if we 

 suppose it to have been removed before the period under consideration 

 there would still remain a barrier of a height and constitution to 

 render it a formidable task for a few rivulets to attempt in com- 

 petition with the forceful river on its further side. 



Lastly, when one considers that the ancient ' Landwasser ' repre- 

 sented not only the combined Schlappina, Upper Landquart, and 

 Landwasser of to-day, but almost certainly a far greater volume of 

 water owing to the wider extent of the snow and ice-fields on the 

 eastern mountains — a difference of conditions that would not have 

 had proportionate effect on the Calanda-Cotschna ridge — the 

 inequality between the two agencies at work becomes still more 

 conspicuously marked. 



Such are some of the difficulties which, it seems to me, one must 

 overcome before accepting Professor Heim's view. When we 

 endeavour to get an idea of the bed of the ancient * Landwasser,' and 

 attempt to derive from it the present conditions between Klosters 

 and the Davos- Glaris region, we meet with considerations no less 



