Reviews — Egyptian Geology. 277 



and their origin ; (5) tlie detailed description of the solid rocks ; 

 (6) the detailed description of the drifts. 



Then we come to the section Economic Geology — to the subject of 

 mineral lodes, building materials, water supply, and agricultural 

 geology. 



Treated economically, the drifts are composed of blown-sand 

 (forming saudy hillocks), recent intake (forming silt and made 

 ground), alluvium, silty and loamy river-flats, peat and peaty- 

 deposits. Raised beaches, pebbly sandy flats, river-gravel terraces 

 (these are usually from 1 to 3 feet of loam on gravel). Late Glacial 

 flood-gravel (forming stony loam on gravel tending to be water- 

 logged). Sands and gravels of mounds and Eskers (forming dry 

 stony loam on gravel, usually full of limestone). Sand and gravel 

 intercalated in Boulder-clay (forming soil nearly like that of Boulder- 

 clay). Boulder-clay containing much limestone (forming clayey 

 loam with stones). Clayey drift mainly of non-calcareous material, 

 including later hill- wash (forming a light, stony soil, varying with 

 character of subjacent rock). 



The five plates are admirably reproduced and well printed. There 

 are also 21 sections and illustrations in the text, including a figure of 

 Oldhamia, which is a very old friend indeed. The memoir will prove 

 a very useful addition to the series of Geological Survey publications. 



V. — Egyptian Geology. 



Survey Department, Public Works Ministry [Egypt]. Geological 

 Survey Eeport. Topography and Geology of the Eastern Desert 

 of Egypt, central portion, by T. Barron and W. F. Hume. 

 8vo ; pp. xii, 332, with maps, plates, and sections. (Cairo, 

 1902 [so dated, but issued May, 1903]. Price 400 milliemes 

 (8s. 4d.).) 



IN this Eeport, which has been expected for many months, the 

 excellent arrangement of previous reports is followed of first 

 giving a complete topographical survey of the region to be 

 geologically surveyed. This brings together a great deal of useful 

 material relating to Egyptology, meteorology, botany, and zoology, 

 of considerable value when dealing with a new area, the features 

 of the country being illustrated by a series of beautiful photogravures 

 of striking scenery and points of geological interest. 



The geology is the result of an examination by two parties of the 

 staff during 1897-98, and the succession of beds dealt with includes 

 Pleistocene, Pliocene, Miocene, Eocene, Cretaceous, all resting on 

 volcanic and metamorphic rocks. The whole of the volcanic and 

 metamorphic beds (with the exception of a few noted in the text) 

 have been planed down by marine erosion, and the Nubian 

 Sandstone has been laid down on the smoothed surfaces. This 

 Nubian Sandstone is considered by the authors to be of Santonian 

 age (Upper Cretaceous), there being no proof of beds older than 

 that period in the district. The Cretaceous limestones overlying 

 the Nubian Sandstone are mainly Middle Senonian (Campanian). 



