404 PBOCEEDINGS OF THE GEOLOGICAL SOCIETY. [May 10, 



those of Sutherlandsliire and Assynt. If this were the case the 

 nomenclature of the Geological Survey would have to be altered, 

 and the rocks of Pistyl and Holyhead no longer termed metamor- 

 phosed Cambrian rocks, but Laurentian. 



Mr. Hicks, in reply, stated that the quartziferous breccias form- 

 ing the central ridge contained so many rolled pebbles, and were, 

 moreover, in places so distinctly bedded, that there could be no 

 doubt of their being sedimentary. Other beds, described as Green- 

 stone in the maps of the Geological Survey, were also distinctly 

 laminated. The non-occurrence of fossils in the more sandy beds 

 he attributed to their having been deposited in very shallow water. 

 The fossils occurred principally in fine-grained beds of a flaggy 

 nature. 



2. On the Age of the Nitbian Sandstone. By Ralph Tate, Esq., 

 Assoc. Linn, Soc, F.G.S. 



Mr. Baueeman, in a recent number of the Quarterly Journal of this 

 Society (vol. xxv. p. 27), has discussed at some length the opinions 

 advanced respecting the age of the sandstone strata underlying the 

 Cretaceous limestones, and resting upon the granitic and schistose 

 rocks, in Sinai. These rocks belong to the same series of sandstones 

 described by Russegger as occurring in Egypt, Nubia, and Arabia 

 Petrsea, un^er the name of " Nubian Sandstone." 



Though the facts that I have the honour to submit to the Society 

 may be stated in a few words, yet it seems desirable to recapitulate 

 briefly the views that have been advanced as to the period of depo- 

 sition of the strata in question, the better to explain away those in- 

 ferences which are so much at variance with my own. 



In the first place, it appears, from the circumstance of the 

 Nubian Sandstone being overlain conformably by approximately 

 horizontal strata of Cretaceous age, that this formation has been re- 

 garded, in the absence of palaeontological evidence to the contrary, 

 as forming part of the Mesozoic group of rocks. Thus Russegger 

 colours and describes it as Lower Cretaceous in his maps ; and Bauer- 

 man, guided by the lithological similarity of its strata to the Lower 

 New Red Sandstone about Chester, has placed it on the horizon of 

 the Trias ; whilst Eigari Bey seems to have regarded the tripartite 

 arrangement and lithological features of the series as sufficient tests 

 by which to assign the whole to the Trias, " taking the limestone as 

 representing the Muschelkalk, although the evidence for this de- 

 termination (other than lithological character) is not very clear "*. 



In the second place, the fossils which have been obtained from 

 the limestone separating the sandstone into two great masses are, 

 for the most part, fragmentary, in bad condition, or otherwise unde- 

 terminable. Hence the palaeontological evidence is of a most con- 



* Bauerman, he. cit. p. 27. 



