Beports and Proceedings — Geological Society of London. 135 



Further to the eastward the important glaciers of the valley of 

 Argeles and of Aure are described, and then the glaciers of the 

 Garonne, the most important of the Pyrenees. The portion of the 

 range drained through this valley has an average elevation of 

 2560 m. (8400 feet). From the evidences of the ice action in the 

 higher districts of the Garonne, the conclusion is arrived at that the 

 line of permanent snow in the Glacial period was about 1700 m. 

 (5576 feet). 



On the south side of the Pyrenees the author describes the course 

 of two of the ancient ice-streams ; that of the valley of the Gallego, 

 which had a length of 45 kilom., and that of the Ara valley 40 

 kilom. in length. These correspond with the glaciers of Ossau and 

 Argeles on the north side, which have respectively an extension of 

 40 and 55 kilom., but whereas these latter advance beyond the foot 

 of the mountains to the level of 400 m. (1312 feet), the former, on 

 the south side, do not descend below 800 m. (2624 feet). 



The ancient glaciers on the south side of the Pyrenees, not only 

 terminated at a higher level, but they were also far shorter than 

 those on the north side, and these differences arise, not from the 

 configuration of the ground, but in the different intensity of the 

 glacial phenomena on the two sides. It is therefore probable that 

 the ancient snow-line on the south side was 300 m. higher than on 

 the north, or at a level of 2000 m. (6560 feet). The ancient snow- 

 line was also higher from west to east, and the evidence shows that 

 the ancient phenomena were developed under similar conditions to 

 those now existent, and may be considered as an intensification of 

 the present. 



Sections showing glacial deposits of different periods do not occur 

 in the Pyrenees, as almost everywhere the moraines rest directly on 

 the older rocks, but indirect evidence of more than a single glacia- 

 tion is shown by the enormous accumulations of gravels, clearly of 

 different ages, which cover the surface beyond the base of the 

 mountains on the north side, sometimes reaching a thickness of over 

 100m. (328 ft.). 



The concluding part of this important paper contains some sug- 

 gestive reflections on the development of the cirques and smaller 

 lakes in the higher portion of the Pyrenees and their relations to each 

 other. A list of the directions of the glacial striae observed by the 

 author is given in an appendix ; and a map of the Pyrenean range 

 and the country on both sides, in which the glaciated areas are 

 distinctively coloured, is of great service in following the author's 

 descriptions. G. J. H. 



lanjiPOi^TS J^isrT:> iPiaooEiEiDiiNra-s. 



I. — Geological Society of London. 



January 28, 1885.— Prof. T. G. Bonney, D.Sc, LL.D., F.R.S., 

 President, in the Chair. The following communications were read : 



1. " The Boulder-clays of Lincolnshire : their Geographical Range 

 and Relative Age." By A. J. Jukes-Browne, Esq., B.A., F.G.S. 



The author commenced by referring to the late Mr. Searles V. 



