82 REVIEWS 
masses, causing considerable metamorphism, and resulting in a great 
variety of schists. ‘This series is classed as Archean. 
The great group of rocks resting unconformably on the Archean, 
and below the Cape System (the upper part of the pre-Karroo group), 
has not yet been correlated with the formations of other countries. ‘They 
consist of slates, quartzites, grits, conglomerates, and dolomites. In the 
Transvaal the group has a thickness of 35,000-40,000 feet, and includes 
three unconformable systems; the lower one of which, the Witwatersrand,. 
consists of twelve formations and has a thickness of 20,000 feet. ‘The 
conglomerate beds of the Witwatersrand contain valuable gold deposits, 
having an output, in 1904, of about $70,000,000. ‘The second system 
of the group is largely volcanic; the third is made up of clastics and dolo- 
mites. 
The Cape system consists in its best development (south Cape Colony) 
of three conformable series of slates, quartzites, shales, and sandstones. 
The middle series, the Bokkeveld, contains the oldest recognizable fossils 
found in South Africa. ‘They are of Devonian age. 
The ‘‘Karroo system” is a conformable series beginning with Permo- 
Carboniferous strata, and extending to the end of the Triassic. The 
system has a thickness of about 20,000 feet, and is composed of sand- 
stones, shales, and conglomerates. It outcrops in an elliptical north- 
east-to-southwest area covering three-fourths of South Africa. In 
south Cape Colony it rests conformably upon the Cape system, but 
elsewhere it is unconformable on older rocks. At the base of the system 
is the Dwyka glacial conglomerate of Permian age. 
The ‘Coastal system’? (Cretaceous) consists of two series occurring 
in different regions; one is of Lower, the other of Upper Cretaceous age. 
Post-Cretaceous beds are represented by superficial deposits, usually 
cemented, which probably range from Tertiary to quite recent, but in 
the absence of fossils they are not classified. 
The igneous rocks of known age are discussed along with the sedi- 
mentary series and chap. 1 of Part IV treats some volcanic rocks of 
doubtful stratigraphical position. 
Chap. ii of Part IV is devoted to the occurrence and origin of the 
diamond bearing deposits. 
In Part V the authors discuss the correlations of the strata of the various 
regions of South Africa and their position in the geological column. The 
correlation tables here and in other parts of the book are especially valuable. 
The chief subdivisions are here reproduced. 
