NA TURE 



ZZ1 



THURSDAY, AUGUST 13, 1908. 



GEOLOGICAL EXPLORATIONS IN SINAI. 



The Topography and Geology of ihc Peninsula of 



Sinai {Western Portion). By T. Barron. Pp. 241; 



illustrated. (Cairo : National Printing Department, 



190;.) 

 r \ Xatui;e for .September iq, 1007, we directed at- 

 •L tention to the memoir by Dr. W. F. Hume on 

 I he topog-raphy and geology of south-ea.stcrn Sinai. 

 We have now before us an account of the western 

 ])ortion of the peninsula by the late Mr. T. Barron, 

 who was assisted in the topographical part of his 

 work by Mr. S. T. Hardwick. This new volume does 

 not compare in interest or lucidity with the previous 

 one, but any defects must be dealt with gently when 

 we bear in rhlnd the transfer of Mr. Barron to the 

 Sudan, and the termination of his promising career 

 by death in that region. He has given us, at any 

 rate, a detailed account of his observations on the 

 topographv and geology of western Sinai that will 

 be useful enough to anyone visiting the ground, but 

 otherwise difficult to follow. Thus, too few names 

 are given on the geological map, and it is by no 

 means easy to define the lines of geological section 

 that are given in four folding plates. 



The geological formations include gneiss and 

 schists, great masses of red and grey granite, diorite, 

 and Carboniferous Limestone and Sandstone, which 

 together form the higher grounds of the interior. On 

 the coast at Gebel Abu Darba there is a fringe of 

 red granite bordered inland by Nubian Sandstone with 

 overlying higher Cretaceous and Tertiary strata. As 

 shown in one of the sections, this belt is separated 

 from the main group of older strata in the interior 

 by the plain of El Qa, and further east by another 

 tract of Cretaceous rocks, which are bent into a broad 

 anticline with steep westerly inclination towards the 

 plain, and faulted on the other side against the 

 gneiss. 



The plain of Qa, described as a gravellv expanse, 

 wind-swept and without shelter, is formed of a very 

 mixed series of fluviatile, lucustrine, and marine de- 

 posits of Pleistocene and recent age, with a cover- 

 ing of igneous boulders from the hills and blown 

 sand. Raised coral reefs and breccia border the greater 

 part of the coast. Some of the sands of the nlain 

 are bound together with common salt and carbonate 

 of lime. 



The record of Pliocene strata is new. They consist 

 of limestones with many pectens and echinids, and 

 also teeth of Carcharodon megalodon, a form familiar 

 to workers in the nodule-bed of the Suffolk Crag. 



Particulars are given of the Eocene strata, with 

 their nummulites, also of the Cretaceous divisions, and 

 the author acknowledges his indebtedness to Mr. R. 

 Bullen Newton for the determination of fossils from 

 these and other strata. Some well-known European 

 forms are recorded from the Carboniferous rocks, but, 

 as is customary nowadays, the species are identified 

 less confidently than in the earlier quoted lists. 



The grey granite is regarded as one of the most 

 NO. 2024, VOL. 7(S1 



valuable ecoijqmic products, being suitable for 

 statuary purposes. Iron and manganese ores are like- 

 wise of some importance. There are also turquoises, 

 which, in the author's opinion, might be worked to , 

 more profit with improved methods of mining. He 

 inclines to the view that they were form&d By per- 

 colating water, the precipitate being afterwards sub- 

 jected to enormous pressure. The gems occur in 

 " pockets " in sandstone of Carboniferous age in a 

 region that has been affected by considerable earth- 

 movements, as evidenced by the faulting and folding. 



.'\ few remarks are made on the age of the rift of 

 the Gulf of Suez, assigned by Neumayr and Blancken- 

 horn to the Middle Pliocene. The area of the gulf 

 appears to have been a land surface in early Tertiary 

 times, but at the close of the Oligocene or during the 

 Lower Miocene it became depressed so as to form 

 an arm of the Mediterranean — the Miocene fossils 

 having affinities with the fauna of that sea and none 

 with the Indian Ocean. 



.After subsequent elevation and denudation of the 

 area, and towards the close of L'pper Pliocene times, 

 were formed the faults which bound the igneous and 

 sedimentarv ranges on either side of the gulf and the 

 Isthmus of Suez. Subsidence then took place, and 

 the Red Sea, which had by this time come into exist- 

 ence, invaded the depression. After this were pro- 

 duced the faults which bound the present gulf parallel 

 to the older dislocations, and these are evidenced by 

 raised beaches at different levels. The faults on the 

 eastern side are somewhat older than those on the 

 western side, as the series of beaches on the western 

 side indicate a gradual rise after the actual fracture 

 took place on the Sinai side. At the close of the 

 Pliocene or beginning of Pleistocene time, sub- 

 mergence is again evidenced by various beach-de- 

 posits and by the brackish-water beds of El Qa. In 

 conclusion, the author points out that " although geo- 

 logically the Gulf of Suez was in existence before the 

 Red Sea, in point of age the fractures bounding the 

 former are vounger than those which produced the 

 latter." ' H. B. W. 



.4 TREATISE ON AERIAL FLIGHT. 

 Aerodynamics : Constituting the First Volume of a 

 Complete Work on AUrial Ftiglit. Bv F. W. 

 Lanchester. (London : A. Constable and Co., Ltd., 

 1907.) Price 21S. net. 



THE book before us is the first volume of a com- 

 plete treatise on aerial flight, and is to be fol- 

 lowed by a volume on " aerodonetics," a word coined 

 by the author to denote the theory of the motion and 

 equilibrium of bodies in the air. The author, by the 

 way, is rather fond of coining new words; some of 

 them — aerofoil, for example — are very happily chosen, 

 and we hope that they may be adopted by subsequent 

 writers on the subject. So far as mathematical theory 

 is concerned, aerodynamics as applied to problems of 

 flight does not differ from hydrodynamics, for with 

 the small changes of pressure that accompany the 

 motion of a flying machine, the compressibility of the 

 air does not sensibly affect the motion. The first 

 chapters, which deal with the theory of aerodynamics, 



Q 



