1134 Capt. Newbolcts Geological Specimens. [No. 132. 



shores of the Red Sea by Gebel Ezzeit, and the semi-active volcano of 

 Gebel Tir, through the Straits of Babel Mandel to Aden. My friend 

 Lieut. Cruttenden, I. N., informs me, that volcanic rocks occur on 

 the opposite shore of Abyssinia. 



The singular gulf of the Red Sea is on the direct line of this volca- 

 nic zone, the existence of which is doubtless connected with the pro- 

 fuse growth of its submarine zoophytic forests. 



The limestone cliffs on each side, like those of Dover and Calais, 

 bear a striking petrological resemblance to each other ; and, if we sup- 

 pose them to have been once continuous over the tract now covered by 

 the waters of the Red Sea, and engulphed, like the centre of the Val del 

 Bove, by some great subterraneous displacement of matter, we need 

 not go far to search for the sub-marine quarries, whence were derived 

 the materials of these curious and beautiful calcareous productions.* 



The beds of limestone extend easterly, far beyond the borders of the 

 Red Sea into Arabia and the Holy Land, interrupted in a few places by 

 volcanic and plutonic rocks, and probably into Syria ; where, in the 

 vicinity of Beyroot, I have seen a rock very much resembling the com- 

 pact, buff, waxy limestone of the Gebel Ataka range, flanking the 

 western shore of the Gulf of Suez. Mr. Weaver* states the compact 

 limestone rocks in the North of Arabia to be, in the mass, composed of 

 coral animalcules of the European chalk, of which Mr. Lonsdale found 

 about a thousand in a pound weight of rock, chiefly fragments of 

 minute corallines ; others entire foraminifera and cytherinae. These 

 animalcules, however, Mr. Lonsdale informed me, were not confined 

 to the chalk, but existed also in supra-cretaceous limestone ; hence they 

 cannot be received as deciding the question of continuity or identity 

 of strata. A large portion of the sands of the Libyan desert consists 

 of bryozoa, a marine animal resembling sand grains ; marine shells 

 also occur in it, which may be regarded as additional proofs of their 

 pelagic origin : since they are distinct from those found in the rocks 

 whence the sands were derived. 



Mr. Bowerbank has found vast numbers of foraminifera in the 

 Egyptian agate (Egyptian pebble, No. 2,) unequally distributed through 

 the layers composing the stone ; but could not detect, in any of the 



* London Philosophical Magazine, for April, May, and June, 1841. 



