374 Reports and Proceedings — 



tioii which will enable even the non-scientific visitor to appreciate 

 more fully the teachings to be derived from the study of the remains 

 here preserved illustrative of the past life of the globe. 



A general notice is given of the geologieal characters of the 

 different formations, including the geology of Leeds, as well as brief 

 descriptions of the natural history and relation to existing forms of 

 the more important fossil plants and animals in the collection, and a 

 list of works and papers on Yorkshire Geology, the whole guide re- 

 flecting much credit on the Curator who prepared it. 



Geological Society of London. — June 25th, 1873. — Joseph 

 Prestwich, Esq., F.E.S., Vice-President, in the Chair. — The following 

 communications were read : — 1. " On six Lake-basins in Argyll- 

 shire." By His Grace the Duke of Argyll, K.T., F.E.S., President. 



The author referred to the part ascribed to glacial action in the 

 formation of lake-basins, and described the basins of six lakes in 

 Argyllshire, the characters presented by which seemed to him in- 

 consistent with their having been excavated by ice. Among these 

 lakes were Loch Fyne, Loch Awe, Loch Leckan, and the Dhu Loch. 

 The upper part of Loch Fyne was said to be cut off from the rest by 

 a bar of islands, with only one or two deeper passages. The country 

 about Loch Fyne was described as consisting of Upper and Lower 

 Silurian mica-slates, which have been violently contorted, their 

 normal strike being indicated by the direction of the valleys. Loch 

 Fyne occupies a niche in the slope of the rocks, having an escarp- 

 ment on one side and the shelving strata on the other. The exist- 

 ence of a fault along the line of the loch was probable, but could 

 not easily be ascertained. Its greatest depth in this part was said 

 to be 84 fathoms. Its banks show marks of glaciation, whereon the 

 surface is well adapted for their preservation ; the strongest marks 

 are on those rock-faces which look up the loch. Between Loch 

 Fyne and Loch Awe the mica-slates are interstratified with granite, 

 which the author believed to have been forced up between the 

 planes of stratification by the pressure caused by the falling in of 

 the mica-slates, as fragments of the latter rock are imbedded in the 

 granite. The author described the different structure of the two 

 banks of Loch Awe, the upper part of which seemed to him to lie 

 in a synclinal trough ; and its waters were only prevented by a low 

 col from finding their way to the Atlantic in this direction, instead 

 of from the lower end. The formation of the basin of Loch Awe 

 seemed to the author to be due solely to geological structure, as was 

 also the case with another lake beyond the head of Loch Awe. The 

 surrounding country was said to be full of smaller lake-basins, the 

 formation of which might be due to the denudation of the softer 

 mica-schists lying below the granite ridges, but in some cases the 

 basins were excavated in the latter. Loch Leckan was mentioned 

 as an example. It is about a mile long, from 100 to 200 yards 



