1873.] B0NNEY ALPINE LAKES. 387 



Karls Eisfeld (the only glacier of any size now left) ever scooped 

 out the Wildbachthal (which is the smaller of the two valleys), it 

 must have followed a very tortuous course, and have left but little 

 trace behind on that part of the channel which it occupied for the 

 longest time. 



Again, from the head of the Traunthal and all along the south 

 end of the present lake, a magnificent limestone wall extends 

 without a break, rising to a height which I should estimate 

 (including the slopes of debris below) at not less than 2000 feet. 

 The uniformity of this wall (the strata of which run tolerably level) 

 is only interrupted by five cirque-like recesses, the largest of which 

 is exactly at the head of the present lake*. This cirque lies 

 precisely in the line which we might fairly expect the principal 

 glacier of the Dachstein (if it cut out the Hallstadt lake) to have 

 taken. In that case, we must suppose a glacier capable of cutting 

 out a vertical precipice with a steep slope below, together full 2000 

 feet high. But if this be impossible, the cirque must be either pre- 

 glacial or post-glacial. If the former, then the valley must have 

 existed nearly in its present condition before the glacier occupied it, 

 and thus the glacier's share in eroding the lake must have been 

 small ; for if it had been powerful enough to erode the basin, say to 

 its present depth of about 600 feet, surely it must have worn back 

 the great cliff, over whose edge it descended, into a slope of more 

 moderate inclination, as shown in the annexed diagram (fig. 3) by 

 line ABD. If the cirque is postglacial, and 

 the glacier formerly descended some such slope Fig. 3. 



as AKC, then the materials since cut away c ,.— 7 D 



by the stream (composing the part ABCK) 

 ought to have formed a considerable delta at 

 the head of the lake. Apart, however, from 

 this, I am convinced that the existing talus 

 heaps are a full measure of the total post- 

 glacial denudationf . Finally, the Traunthal 

 itself cannot have been cut out by a glacier, 

 because the mountains above the cliffs at its ■ A - 



actual head are comparatively low, and slope rather the wrong way, 

 and because the Traun descends through a true river-valley from 

 land of no great elevation. 



North of the village of Hallstadt, at Gosauniuhle, the lake 

 receives the drainage of the western face of the Dachstein from the 



* A steep ascent of perhaps 800 feet leads from the lake (by a curious hollow 

 named the Kessel) to a small alp below the cliff. This rises full 1000 feet 

 above the floor of the cirque, now almost wholly covered with debris taluses 

 from the cliff, which is stained by lines of rain-drip, furrowed by three or four 

 watercourses, the largest of these having cut for itself a small Klamm. 



+ If there ever was a moraine in the cirque it is buried beneath the taluses ; 

 for the cirque is filling up. All the water which descends into it is swallowed 

 up (as is common in the North-Eastern Alps) ; so there is little power to remove 

 the debris from the floor. I may add that repeated investigations since those 

 described in my communication (Quart. Journ. Geol. Soc. vol. xxvii. p. 312) 

 have convinced me that the cirques are in their essential features preglacial. 



K/ 



