Geological Society of London. 237 



reversed dip of the disturbed molasse-strata between the lakes of 

 Zurich and Zng. During tbe second and third Ice-periods, the 

 original lake-basin was gradually rilled with glacial and fluviatile 

 deposits at both ends, and was finally restricted to its present 

 dimensions by a post-Glacial bar deposited at its lower end by 

 a tributary river. In the author's view, the other Subalpine lakes, 

 extending from the Lake of Constance to Lac Bourget in Savoy, 

 owe their origin and present limits, in the main, to the operation of 

 similar causes. 



(6) With regard to the main question, the author averred that the 

 Lower and Middle Pliocene period was, in Switzerland, entirely one 

 of erosion and denudation on a prodigious scale. Irrespective of the 

 evidence he had adduced, he was therefore driven to the conclusion 

 that at the advent of the first Ice-period in Upper Pliocene times, 

 the principal Subalpine valleys must have been already excavated 

 approximately to their present depth ; and that ever since then the 

 action of the great Alpine and Subalpine rivers has been, as it is 

 still in our own day, mainly directed to regaining the old valley- 

 floors by removing those enormous accumulations of glacial and 

 glacio-fluviatile material, which are respectively the direct and 

 indirect products of three successive and general glaciations. 



3. " Notes concerning certain Linear Marks in a Sedimentary 

 Eock." By Prof. J. E. Talmage, D.Sc., F.G.S. 



The marks described in the paper occur in a fine-grained argil- 

 laceous sandstone referred by the U.S. Geological Survey to the 

 Triassic or Jura-Trias period, which is found on a low tableland 

 within two miles of the bluffs overlooking Glen Canyon. The 

 marks commonly appear as straight lines intersecting at right angles, 

 but some have a pinnate distribution, suggesting engravings of frost- 

 flowers. A description of the markings is given ; and various experi- 

 ments made in the laboratory to illustrate the effects of formation of 

 crystals formed over sediment are described. 



III.— March 25th, 1896.— Dr. Henry Hicks, F.E.S., President, in 

 the Chair. The following communications were read : — 



1. " On Submerged Land-surfaces at Barry, Glamorganshire." 

 By A. Strahan, Esq., M.A., E.G.S. With Notes on the Fauna and 

 Flora by Clement Beid, Esq., F.L.S., F.G.S., and an Appendix on 

 the Microzoa by Prof. T. Eupert Jones, F.E.S., F.G.S., and F. 

 Chapman, Esq., F.E.M.S. (Communicated by permission of the 

 Director-General of H.M. Geological Survey.) 



Excavations for a new dock at Barry have disclosed a series of 

 fresh-water or slightly estuarine silts with intercalated peats, below 

 sea-level on the north-eastern side of the island. The site of the 

 excavation was overflowed by the tide until the year 1884, when the 

 docks were commenced. The newest deposits seen are therefore 

 Blown Sand, Scrobicidaria-c]ny, and sand or shingle with recent 

 marine shells. 



These rest on an eroded surface of blue silt, with sedges in 



