On the Age of the Nubian Sandstone

Abstract

M r . B auerman , 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 Petræa, under 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 deposition of the strata in question, the better to explain away those inferences 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 regarded, in the absence of palæontological 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 Bauerman, guided by the lithologieal similarity of its strata to the Lower New Red Sandstone about Chester, has placed it on the horizon of the Trias ; whilst Figari Bey seems to have regarded the tripartite arrangement and lithological features of the series as suflleient tests by which to assign the whole to the Trias, “taking the