Vol.540 TSE STRTTCTTTRE OF THE DAVOS VALLEY. 289 



Wolfgang moraine ; while the powerful Sertig river was cutting 

 rapidly through the great mass of detritus at Frauenkirch. 



The result of this would be a breaking-down of the southern 

 barrier, and the flow of the lake-waters in that direction, carrying 

 with them the currents of the Dischma and the Fluela. The 

 lowering of the lake-level would stop any outflow over the Wolf- 

 gang saddle, and the present conformation of the area would be 

 established. 



Discussion. 



Prof. Bonnet said that he thought that the Author was quite 

 right in his main contention, namely, that the flow of the water from 

 the trough at Davos had been to the north, and that the blockage 

 north of the Davoser See was quite unimportant, though he believed 

 that he had seen rock in situ. He thought, however, that the 

 original watershed had been well to the south of Frauenkirch, 

 and quoted a number of similar cases of beheaded valleys. That 

 seems clear from the north-western course of the tributaries which 

 join the Davos trough from the east. In other words, he thought 

 the Glacial and post-Glacial changes superficial, and that the main 

 sculpturing of the region was done in earlier times. 



Mr. Haemer wished to add, as a case in point, that the old valley, 

 from the centre of which the Waveney and the Little Ouse took 

 their rise, flowing the one eastward and the other westward, was 

 occupied, near the present watershed, by a considerable thickness 

 of the Chalky Boulder Clay. 



The President and Mr. Whitaker also spoke. 



The Author said he was very glad to have Prof. Bonney's support 

 on the main principles of his paper. As regarded details, he was 

 prepared to admit that the old watershed might have been somewhat 

 south of the Sertig river, and that that river might once have 

 belonged to the same system as the Eluela and the Dischma. The 

 depth of the Ziige gorge indicated that the watershed could not have 

 been much farther south. In the northern part he admitted that 

 the solid rock occurred near the river at Laret, but still far from 

 the eastern rock-slope ; and he believed that it could not be found 

 in the etream-bed south of Selfranga. 



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