328 Revieus — Geology of Cape of Good Hope. 



There are appendices containing notes on the quick determination 

 of common rainei'als, descriptions of common rocks, notes on topo- 

 grapliical and geological maps, and suggestions for itineraries. 



The illustrations are profuse, well - executed, and effective, 

 llefereuces to literature are given at the ends of chapters, and there 

 is a good index. 



II. — South Afeican Geology. 



Geological Survey of the Cape of Good Hope. — The fifteenth 

 Annual Report of the Geoloiiical Commissioners of this Province, 

 under the direction of Dr. A. AV. Rogers, contains records of the work 

 accomplished during 1910 (Cape Town, 1911). Dr. Rogers describes 

 portions of the divisions of Beaufort West, Fraserburg, Yictoria West, 

 Sutherland, and Laingsburg. lu dealing with the physical features 

 he describes the 'pans' or bare, mud-covered surfaces on which water 

 stands to the depth of an inch or so after rain ; a f(^\v ai'e well-defined, 

 but most are ill-defined, measuring from 5C0 yards or less to over two 

 miles in width. The clearh' marked pans in the district are entirely 

 surrounded by dolerite, the ill-defined and shallow pans occur on 

 mudstone and sandstone. The depressions in the dolerite appear to 

 be due primarily to rapid local disintegration of the rock, and to the 

 wind having probably removed the loose material. Dr. Rogers gives 

 some account of the Beaufoit Series, and also of its many vertebrate 

 lemains from data sup])lied by Dr. R. Broom ; he also describes the 

 Xieuweveld coal, which occurs in fissures of a sandy mudstone, and 

 near the southern end of great intrusions of dolerite. Professor 

 Schwarz lias suggested that the coal was carried to its present position 

 by heated water. Analyses show that the coal, compared with other 

 South African coals, contains low amounts of ash, but usually large 

 amounts of moisture and also of volatile hydro-carbons. Paiticulars 

 are given of the dolerites and also of granophyres, of the screes 

 resulting from the weathering of the dolerite crags, and of other 

 superficial accumulations. 



Mr. A. L. Du Toit contributes an account of Maclear and portions 

 of Engcobo, Mount Fletcher, Qumbu, and Mount Frere, a district 

 formed of the Beaufort and Stormberg Series, with numerous sheets 

 and dykes of dolerite. The higher part of the Stormberg Series 

 consists of the Drakensberg volcanic beds, basaltic lavas with 

 occasional thin beds of sandstone and volcanic ash, 3,000 feet and 

 more in thickness. The great escarpment of the Drakensberg rises 

 from 4,000 to more than 8,000 feet above sea-level. The Molteno 

 Beds, which form the base of the Stormberg Series, beneath the Cave 

 Sandstone, contains seams of coal, many plant-remains (j^%/«??/<;W/ff, etc.), 

 and blocks of silicified wood. 



There is also a report by Mr. Du Toit on the copper-nickel deposits 

 of the Insizwa, Blount Ayliff, East Griqualand. In this region the 

 Beaufort Series, consisting of shales, flagstones, and thin sandstones, is 

 penetrated by sheets and dykes of the Karroo dolerites, including 

 gabbro ; and the copper-nickel ores are confined, more or less, to the 

 contact of gabbro with the altered sediment, but mostly to the igneous 

 rock. The surrounding Beaufort Beds have been metamorphosed into 

 biotite and cordierite horufels. 



