554 Reviews — Rocks and their Origin. 



with other matters. The geographical term " South Africa " is 

 also used in an extended way, so as to include not only the whole 

 of the Union, but also Rhodesia, South-West Africa, Angola, the 

 Belgian Congo, the territory formerly known as German East 

 Africa (the Tanganyika Territory of the present time), Madagascar, 

 and Portuguese East Africa. In South Africa in this wide sense, 

 more perhaps than in any other country, owing to the special 

 economic conditions and the dominant position of the mining 

 industry, geology plays a prominent part in the general life and 

 thought of the people, and some knowledge of it is almost universal. 

 The work cannot fail to be of the greatest use to geologists interested 

 in this large section of the continent, as well as to others dealing 

 with more general problems, on many of which South African 

 studies have thrown so much light. 



E. H. R. 



Rocks and their. Origins. By Professor G. A. J. Cole, F.R.S. 

 pp. viii + 174, with 20 illustrations. Cambridge University 

 Press, 1922. Price 4s. 



A T its first appearance in 1912 this book afforded an admirable 

 -'-^ summary of the facts and theories derived from the study of 

 rocks up to that date. We have recently received for review a copy 

 of the same work bearing on the title-page the date 1922 and the 

 impress " Second Edition " on the fly-leaf and on the paper jacket. 

 A careful collation of this with an original copy of 1912 has revealed, 

 besides the alteration of date, a slight modification of the last 

 sentence of the preface and the replacement in the bibliography 

 of an English work by an obscure German periodical, dated 1911, 

 which will be inaccessible to the vast majority of readers. Otherwise 

 the two appear to be absolutely identical. 



In the last ten years the study of roclcs has made great advances ; 

 in particular the detailed petrography of the sediments may be said 

 to have come into being within that period, and the investigation 

 of the origins of both igneous and metamorphic rocks has made 

 great strides. This book therefore, though excellent as far as it goes, 

 is in no way up to date. It is much to be regretted that the 

 publishers have not taken the opportunity of bringing out a real 

 new edition, setting forth in the same attractive style the recent 

 great advances in petrology. 



An Introduction to Sedimentary Petrography, by H. B. 

 MiLNER. pp. 125, with 15 plates (not numbered), 7 text- 

 figures, and a table. London : Murby, 1922. Price 8s. Qd. 



'T^HIS book has been written mainly as a help in the study of loose 

 -*- detrital sediments, a branch of petrography which has greatly 

 increased in importance of late years in connexion with numerous 



