Llandovery and Associated Rocks of Montgomeryshire. 467 



March 22nd.— Prof. W. W. Watts, ScD., M.Sc., F.R.S., 



President, in the Chair. 



The following communication was read : — 



1 Some Observations on the Eastern Desert of Egypt, with 

 Considerations bearing upon the Origin of the British Trias.' By 

 Arthur Wade, B.Sc, E.G.S. 



This paper deals chiefly with phenomena observed in the En stern 

 Desert of Egypt, bordering the Gulf of Suez and that part of the 

 Red Sea which is adjacent to its junction with the Gulf. The mounds 

 of igneous debris which flank the coastal hill-ranges are described, 

 and their origin is discussed and connected with the raised-beach 

 phenomena present in the area. The distances to which fragments of 

 igneous rock derived from these hillshave travelled in Egypt are shown. 



The shore-sands are next dealt with, and their origin ascribed 

 mainly to the breaking down of local rocks, and not necessarily to 

 the denudation of Nubian Sandstone areas as has been supposed. 

 In the marly beds connected with the recent shore-deposits, tiny 

 dolomite-rhombs, similar to those found by Dr. Cullis in the Keuper 

 Marls, are present. Some effects of wind-blown sand are described, 

 especially the wedging of the sand-grains into cracks produced by 

 other forces of disintegration. 



Deposits of rock-salt and gypsum are being laid down at present 

 in the area. The alteration of the calcium carbonate in recent 

 shell-beds to gypsum, with the accompanying destruction of organic 

 remains, is noted ; and its significance with regard to the origin of 

 gypsum-beds and the concurrent absence of fossils in some of the 

 older series of strata is pointed out. Analyses of different deposits 

 are given, and the presence of sodium carbonate and epsomite- 

 crystals is proved in the encrustations upon recent fossil shells. The 

 characters of the massive older gypsum- and rock-salt deposits are 

 described, together with the distribution and lithological changes in 

 the beds when traced across the area by means of borings and 

 outcrops. The origin of the gypsum series is shown to be connected 

 with inland salt-lake conditions, and evidence is presented which 

 suggests that these conditions were contemporaneous with the 

 Oligocene continental period in Egypt, and with the formation of 

 the well-known beds of the Eayum in the Western Desert. A 

 sketch-map showing, for the first time, the geology of the islands 

 situated in the mouth of the Gulf of Suez accompanies the paper. 



April 26th.— Prof. W. W. Watts, Sc.D., M.Sc, F.R.S., 

 President, in the Chair. 



The following communication was read : — 



' The Llandovery and Associated Rocks of North-Eastern Mont- 

 gomeryshire.' By Arthur Wade, B.Sc, E.G.S. 



The area dealt with in this paper is in the neighbourhood of 

 Welshpool. It comprises part of the Severn Valley and the whole 

 of the Vale of Guilsiield. A summary of the work done in the 

 area is first given, and the deficiencies of the present geological 

 map are pointed out. 



