Reviews— Prof. Forel—On Glaciers. 



569 



Mr. Gunn, and he has found in the red sandstones, which extend 

 along tlie eastern shore, and across the southern half of the island, 

 a contemporaneous volcanic group. It is considered highly probable 

 that these beds are of Permian age. 



The older rocks and the Tertiary dykes of the south-east ot bkye 

 have been mapped by Mr. Clough, while Mr. H. B. Woodward has 

 been engaged in the survey of the Jurassic rocks along the north- 

 eastern borders of the island. With Mr. Symes in Cantyre, Mr. 

 Wilkinson in Islay, Mr. Hill in the region between Loch Fyne and 

 Loch Awe, Mr. Grant Wilson in Banff and Elgin, and Mr. Greenly 

 (who has since retired) in Sutherland, the Geological Survey has made 

 progress in various parts of Scotland. 



In Ireland the work of revision has been carried out in different 

 areas by Messrs. Egan, Kilroe, McHenry, and SoUas. The Croagh 

 Patrick quartzite is now assigned to the Llandovery formation. 

 In the tract of ground between Clifden and Oughterard there is a 

 complex series of rocks which are considered to be equivalents of 

 the Dalradian rocks of other regions. In the district of Pomeroy, 

 in Tyrone, there is a belt of igneous rocks, lying between the 

 Silurian and Old Red Sandstone rocks on the south and the 

 crystalline schists on the north; and it has been found that they 

 include lavas interleaved with cherts and jaspers exactly like those 

 associated with the igneous rocks at the edge of the Highlands. It 

 is surmised that the cherts, and certain overlying shales, etc., may 

 prove to be of Arenig age. 



II— Les Yakiations periodiques bes Glaciers. Disoours pre- 

 ' LiMiNAiRE. Par F. A. FoREL, President de la Commission 

 Internationale des Glaciers. Archives des sciences physiques 

 et naturelles. Geneve. Vol. xxxiv, p. 2U9. 



PROFESSOR FOREL commences by relating the formation of his 

 committee, " sur I'initiative " of the writer of this notice. Each 

 member, he tells us, is to organize— as seems best to him, and after 

 the most useful fashion— historical, present, and future studies ot 

 glacier phenomena, and publish such in the periodicals of his own 

 country ; and a summary is to appear annually in the Archives des 

 sciences, etc., of Geneva. He then proceeds to the consideration of 

 what the phenomena to be studied consist in. Much of this ground 

 has already been put forward by the writer, but there are points 

 and extensions dwelt upon by Professor Forel which it may be 

 acceptable to touch upon. 



He rightly emphasizes the importance of concentrating our energies, 

 more especially at first, upon the observation of actual advance, 

 retreat, increase or diminution in bulk of glaciers, and to the sunn - 

 taneity or otherwise of their variations in both hemispheres and all 

 latitudes, as also to their relation to meteorological records. 



As regards the study of neves, to the extent and quantity ot 

 which, ot course, much of glacier variation is due, he thinks that, 

 great as is the importance of such observations, we had better for 



