REVIEWS 169 



The material left for the geologist to work upon in this part of the country 

 seems to consist chiefly of such scattered fragments as have escaped denudation. 



In the first place we have a description of beds of the Stonesfield type near 

 Fritwell. These, owing to their fragmentary condition, appear to have escaped 

 the attention of workers. To reconcile the apparent differences between these 

 beds and those of West Oxford is, the writer tells us, the main purpose of his notes. 



One of the most interesting structural details mentioned is the " striping " of 

 certain beds. "A course of blue-black limestone," says Mr. Walford, " bore casts 

 and outlines of crinoidal calices, whilst below and through the block were vertical 

 stripes of metal-green with infillings of grey marl." The striped beds of the 

 Lower Oolite were thought to be of plant remains, but the author considers they 

 are crinoidal. " The blue crystalline limestone of Blackthorn is a weld of ossicles 

 of the brachial arms of a species of Apiocrinus . . . the black stripes piercing 

 the lower bed represent the rootlets." G. W. Bulman. 



Economic Geology. By Heinrich Ries, A.M., Ph.D., Professor of Geology at 

 Cornell University. Fourth Edition, thoroughly revised and enlarged. 

 [Pp. xviii + 856, with 291 figures and 75 plates.] (New York : J. Wiley & 

 Sons, Inc. ; London : Chapman & Hall, Ltd. Price 17s. net.) 



The fourth edition of this work, which was originally known as The Economic 

 Geology of the United States, has been considerably revised, partly rewritten, and 

 enlarged. In a geographic sense, however, its scope is still largely confined to 

 the United States, although description of the more important Canadian mineral 

 deposits is a new feature welcome to British economic geologists. Brief references 

 are also made to well-known foreign occurrences, and the usefulness of the book 

 would have been increased to European students by an expansion of this feature. 



The book is divided into two parts : " Non-metallics " — an ugly term, although 

 it would be hard to suggest a substitute — and " Ore Deposits," of which the first- 

 named occupies a little more than half the book. The first part reveals the 

 surprising scope applied geology has, quite apart from the winning of useful and 

 precious metals. The subjects treated in this part are coal, petroleum, natural 

 gas and other hydrocarbons, building-stones, clay, limes and calcareous cements, 

 salines, gypsum, fertilisers, abrasives, asbestos, foundry and glass sands, graphite, 

 monazite, gems, and underground waters, a list which helps in the realisation 

 how important a part geology plays in the winning and investigation of many 

 essential raw materials. Road metal is the only notable omission from this list. 



Prof. Ries has a great reputation as a specialist in the economic geology of 

 " non-metallics," and this part of the book is of great value. Yet the work plunges 

 at once into the subject of coal, without any preliminary or general discussion of the 

 non-metallics, such as might have been expected, especially as there is an excellent 

 general chapter prefacing the second part of the book dealing with ore deposits. 



Misprints are few, and the book is a pleasure to the eye. " P. Brun " (p. 441) 

 should be A. Briin ; and there are misspellings of " propylitisation " (p. 486) and 

 "porphyry" (p. 518). There are a few clumsy or ambiguous statements, as, for 

 example, in the third paragraph on p. 432. 



The book is a compilation rather than a philosophical treatise on applied 

 geology ; but the facts and figures relating to the various subjects are so well 

 arranged and displayed that it will be very useful as a reference work for student 

 and specialist alike. Its value is greatly enhanced by a fine series of illustrations, 

 and by comprehensive references to authorities at the end of each chapter. 



G. W. T. 



