Revieivs — Topograijliy and Geology of Northern Sinai. 471 



orograpliical maps, etc., and sixty-nine photographs, which are 

 really plates though not numbered as such. Two photographs are 

 usually printed on a page, but there are also several folded panoram.ic 

 views representing features of special interest. A straight line 

 drawn from El Arish to a point on the gulf about 40 kilometres south 

 of Suez passes through the centre of the area, which is over 60 kilo- 

 metres across at its widest part, closing in to about 15 kilometres 

 on Wadi el Arish and 30 at the Gulf of Suez.^ 



The authors begin by giving a succinct account of the route 

 followed. Anyone who reads this account, referring constantly to 

 the maps and photographs, will obtain a vivid impression of the 

 physical features and geological structure of the area, especially 

 if he has previously made himself familiar with the general succession 

 as described in Chapter II. 



The region contains two large plateaux of Eocene limestone, 

 Raha and Muksheib ; three massifs of Upper Cretaceous, Giddi, 

 Fallig, Yellig ; and one of Jurassic and Lower Cretaceous partially 

 encircled by Upper Cretaceous. The Eaha, Giddi, and Muksheib 

 highlands follow each other from south to north at elevations of 

 1,800 feet and over. Though separated by low passes, they may be 

 regarded as one orographical group. This group and the other high- 

 lands are surrounded by vast stretches of sand and gravel at lower 

 levels. The western edge of the Raha plateau is sharply defined by 

 a north-south fault, running approximately parallel with the eastern 

 shore of the Gulf of Suez, at a distance of about 25 kilometres, and 

 known to extend far to the south. Between this fault and the shore is 

 a belt of Miocene rocks traversed by numerous faults parallel to the 

 main one. East of this fault-zone the whole of the area surveyed 

 is dominated by structural features of an entirely different kind. 

 Broadly speaking, the rocks are gently folded so as to form anti- 

 clinal and domal structures along slightly curved lines, bulging 

 towards the south and extending from the zone of north-south- 

 faulting right across the area to Wadi el Arish. In the west these 

 lines run nearly east and west, but as they are traced eastward 

 they become E.N.E.-W.S.W. Three such lines or axes are 

 recognized ; the Giddi- Yellig-Hellal axis in the south, the 

 Maghara axis in the middle, and the Hamaiyir-Reisan axis which 

 is only slightly north of the last. Although gentle folding is 

 characteristic of the district as a whole, there are " steep dip zones " 

 and local disturbances of great intensity, as well as many faults. 

 In Chapter III the authors give detailed descriptions of the 

 topography, stratigraphy, structure, and palaeontology of nine 

 separate districts, carefully recording any evidences of oil- 

 impregnation and the occurrence of domal structures. 



^ Readers should, refer to the paper by Dr. Hume and others on " The 

 Jurassic and Lower Cretaceous Rocks of Northern Sinai ", and especially to 

 the maps which illustrate that paper. Geol. Mag., Vol. LVIII, 1921, 

 pp. 339-47. 



