﻿502 Geological Society : — 



(quartz-chlorite-schists) which cut the Trias, and are therefore 

 post- Triassic. 



(3) The contorted beds in the Clos des Morts Valley are fossilife- 

 rous limestones, and it is from them that the fallen blocks previously 

 recorded were derived. The only recognizable fossil is Calamo- 

 phyllia fenestrate, Eeuss, a characteristic coral of the Gosau Beds. 

 In spite, therefore, of the doubts of Kilian and Diener, the opinion 

 expressed by Neumayr as to the existence of Cretaceous rocks in 

 this part of the Alps is confirmed. 



(4) The earth- movements of the mountain are described : they 

 include ordinary folds, inversions, faults, and an important thrust- 

 plane. 



(5) It is suggested that in addition to the two series of intrusive 

 rocks above-mentioned as pre- and post-Triassic, a third series of late 

 Cretaceous or Tertiary date maybe represented in the MontGeiuvre 

 and Hocciavre masses. 



3. ' Cone in Cone ; its Structure, Varieties, &c.' By W. S. Gresley, 

 Esq., E.G.S. 



The author describes cone-in-cone structure occurring in the 

 Portage Shales of Pennsylvania, and gives details concerning the 

 nature of the structure as seen in these shales. He criticises the 

 explanation of Mr. J. Young as to the origin of the structure, and 

 concurs in a great measure with the views of those who have 

 suggested that the formation was due to pressure acting on con- 

 cretions. 



May 23rd.— Dr. Henry Woodward, F.R.S., President, 

 in the Chair. 



The following communications were read : — ■ 



1. ' On the Stratigraphy and Physiography of the Libyan Desert 

 of Egypt.' By Captain H* G. Lyons, K.E., E.G.S. 



The Nubian Sandstone, wherever seen, rests unconformably on 

 the old rocks called by Sir J. W. Dawson Archaean, and the 

 author finds no case of alteration of sandstone by these rocks, 

 though in one case it is altered by an intrusive dolerite. 



The author considers the Nubian Sandstone to be an estuarine 

 deposit which was formed on an area afterwards gradually invaded 

 by the Cretaceous sea. He considers the whole of the sandstone in 

 the region which he has examined to be of Cretaceous age. 



He describes a series of anticlinals, one set running W.N.W.- 

 E.S.E., and the other N. by E. and S. by W. Many springs of the 

 oases seem to occur along these anticlinals, owing to the beds which 

 contain the water being brought nearer to the surface. Historical 

 evidence is discussed which points to the Nile having reached a 

 higher level in Nubia than it does at present, and it is suggested 

 that variations in the level of the river were caused by earth- 

 movement opposing obstructions to the river's flow. 



The sandstone of Jebel Ahmar near Cairo is described, and its 

 occurrence over a wide area west of Cairo is recorded. The author 

 considers its age to be later Miocene. He believes that, with the 



