REVIEWS ‘ 81 
tinuously applied for a long time, of the material composing the outer 
part of the earth. A flowage of rocks, of the character referred to in 
Professor Chamberlin’s review, may be one of the ways in which the 
material yields to forces continuously applied for a long time, even though 
those forces are not sufficiently great to produce motion if applied for a 
short time only. 
Professor Chamberlin has, in the curve C—C, furnished a statement 
of the manner of distribution of the isostatic compensation with respect 
to depth corresponding to the accretion hypothesis. Since writing this 
review, Professor Chamberlin has been assured that a sub-solution upon 
that basis will be added to the geodetic investigation before the final publi- 
cation is made. 
Joun F. Hayrorp 
Inspector of Geodetic Work 
Chief of Computing Division, Coast and Geodetic Survey 
The Geology of South Africa. By F. H. Hatcu and G. S. CorRstRo- 
PHINE. London and New York: The Macmillan Co., 1905. 
Pp. 348, 2 maps, 89 figures. 
The authors have attempted in this work to put within the limits 
of a small volume the essentials of the geology of South Africa. Their 
long experience in South African geology, both in the Transvaal and 
Cape Colony, has fitted them well for their task. The literature of South 
African geology is especially burdened with a great mass of semi-scientific 
writings which deal with isolated areas, without any attempt at correla- 
tion with neighboring regions, and only recently by the work of the Cape 
Colony and Transvaal surveys, has geological work been carried to a 
stage that would warrant the treatment of South Africa as a unit. The 
book contains some details that were hardly intended for the student 
so far away as America, and, on the other hand, many general points of 
vital interest are passed over all too briefly. This is especially true of 
the physical history and dynamical problems of the region. Nevertheless, 
the volume is a valuable and welcome summary of the geology of this 
distant land. 
The “pre-Karroo” (pre-Permo-Carboniferous) rocks are treated in 
two sections: Section I describes those of south Cape Colony; Section 
II those of the Transvaal and neighboring regions. At the base, in both 
regions, is a series of micaceous slates and quartzites with occasional 
conglomerates and crystalline limestones, into which were intruded granite 
