630 Grohf/ical Society : — 



ice, such extensive basins as those of the principal Alpine lakes, from 

 2 to 8 miles in width and from 470 to 1020 feet in depth, the 

 quantity of water to be dis))laced and expelled in the individual 

 cases ranging from 3500 million to 90,000 million cubic metres or 

 tons. 



5. As regards the more recently-enunciated argument of the 

 Deckenschotter and overlying gravel-exposure in the Lorze Valley, 

 the author points out that, apart from the difficulty of differ- 

 entiating the second and third glaciation-materials in that locality, 

 it is obviously hazardous to deduce from a purely-local phenomenon 

 of this kind, and more especially from ain dip of loose gravel — in 

 contrast with rock or compact conglomerate, — the date of the zonal 

 bending affecting six valley-systems, and extending over more than 

 200 miles along the edge of the Alps. 



6. The author's investigations point to the conclusion that the 

 deep-level Limmat gravel-beds, overlain by the moraine-bars of 

 the third glaciation, were deposited by a river during the second 

 inter-Glacial period ; that the lowering of the valley-floor was 

 initiated in the course of the third glaciation, probably when the 

 lilacier had already reached its maximum extension, about 10 miles 

 below Zurich ; that the zonal subsidence continued throughout the 

 retreat of the ice ; and that the simultaneous formation of the lake- 

 basin should therefore be assigned to the end of the Glacial Period, 

 after which the original basin was, notably at its upper end, 

 restricted to its present dimensions by post-Glacial alluvia. 



7. In conclusion, the author shows that the same arguments 

 apply, in the main, also to the origin and age of the other princijial 

 zonal lake-basins, which he illustrates by longitudinal sections. In 

 his view, the position and depth of these basins, as well as the 

 intervening ground, point to the probabilitj^ that the bending took 

 place not only along one line, bnt along several, more or less 

 parallel, not always continuous lines within the zone between the Alps 

 and the Jura ; that the bending was by no means of uniform depth ; 

 and that, therefore, the Alps did not subside as a rigid mass, but 

 that the zonal bending along their edge merely extended locally for 

 some distance from the deepest points of the lake-basins along the 

 floors of the principal Alpine river-valleys. 



2. ' On a Shelly Boulder-Clay in the so-called Palagonite- 

 Formation of Iceland.' liy Helgi Pjetursson, Cand. Sci. ISTat. 



There is no equivalent in the Tertiary basalt-plaieaux of Britain 

 of the great palagonite-formatioii of Iceland, which Prof. Thoroddsen 

 has shown to be younger than the basalt-formation of the latter 

 island. The basement-layer of the breccia-formation, resting 

 directly upon the basalts, contains glaciated blocks of all sizes, up to 

 6 feet and more in diameter. These ground-moraines are followed 

 by tufaceous sandstones, conglomerate, columnar basalts, other 

 ground-moraiues and volcanic tuffs and breccias. At Burlandshofdi 

 a shelly Boulder-Clay, 70 to 80 feet thick, rests upon the fundamental 

 basalt, which here shows a glaciated surface. Unbroken shells are 

 very rare. Astarte horealis is the most common shell, and Saxkaca 



