1866.] HOLLAND SINAI. 491 



Head ; and at its north-west extremity the Old Ked Sandstone, 

 in the neighbourhood of Peel, coming against the Skiddaw slates. 



May 23, 1866. 



The following communications were read : — 



1. Notes on the Geology of Sinai. 

 By the Eev. F. W. Holland, M.A. 



[Communicated by Sir R. I. Murchison, Bart., K.C.B., F.G.S.] 

 (Abstract.) 



The peninsula of Sinai may be divided into three geological districts, 

 named from the granitic, limestone, and sandstone rocks of which 

 they are composed. 



The whole of the northern portion of the peninsula is occupied 

 by an extensive plateau of limestone, supported on the south by the 

 range of Jebel-et-Tyh, and sloping gradually towards the Mediterra- 

 nean Sea. 



A broad belt of sand, called the Debbet-er-Raraleh, separates this 

 limestone from the southern portion of the peninsula — although 

 small patches of it, apparently underlying the sandstone, are found 

 further south in Wady Badera and Wady Mokatteb, and in the 

 neighbourhood of Jebel Hummam, and also on the north-west of 

 Jebel Serbal, there occur large tracts of a limestone more cretaceous 

 in its character, and abounding with bands of flints. At the latter 

 spot I observed one mountain of Nummulitic limestone ; and a 

 limestone of more recent formation, which abounds with fossils, 

 occurs near Tor and Ras Mohammed. 



The granitic district forms, as it were, the backbone of the southern 

 portion of the peninsula. Its mountains are frequently seamed from 

 top to bottom with veins of porphyry, greenstone, and basalt, which 

 give them a peculiar striped appearance ; this is especially remark- 

 able on the east of Wady Mokatteb, the north-west of Jebel Serbal, 

 and in the wadies between Jebel Musa and Ain Hudera. They are 

 also in some parts capped by a stratum of sandstone of considerable 

 thickness and perfectly horizontal stratification, proving that an 

 enormous denudation has taken place. Both the limestone and sand- 

 stone, when found in close proximity to the granitic rocks, exhibit no 

 change in their structure ; and thus, as well as by their uniform 

 horizontal stratification, they show that they must have been depo- 

 sited subsequently to the upheaval of the latter. The only traces of 

 active volcanic agency which are now to be found in the peninsula 

 are the boiling sulphur-springs and hot caves at Jebel Hummam, and 

 the two warm mineral springs near Tor. The mountains of the 

 granitic district appear to be chiefly composed of syenite; but 

 granite, porphyry, gneiss, mica-schist, and quartzose and horn- 

 blendic rocks occur in many localities. I did. not succeed in finding 

 any traces of metallic ores in this district. 



