lOO REVIEWS 



deposits. These discussions are followed by formal schedules or synopses 

 upon fourteen special topics, such as, e.g.. No. 4, Glaciers and glacial 

 deposits; No. 14, Oil and gas. In these the salient features to be noted in 

 the field are arranged in tabular form so as to be suggestive and directive 

 to geologists, especially when working in lines outside their own special 

 fields. 



The book closes with an appendix giving a list of the ofhcial surveys 

 of the United States, Canada, and Mexico, and the 33 states which 

 conduct such surveys, together with the names of their directors in 1909 

 and an indication of the extent of their publications. 



The booklet, strongly bound in flexible leather, is given a size convenient 



for use in the field and will be a welcome companion of many a working 



geologist. 



R. T. C. 



Geologie der Steinkohlenlager. Von Dannenberg. Erster Teil, pp. 

 197, with 25 figures. Berlin: Gebriider Borntraeger, 1909. 



This work is a critical treatise upon the coal-bearing formations of Cen- 

 tral Europe in which much attention is given to questions pertaining to 

 the mode of origin of the coal and to the relation between the tectonics 

 of the regions and the character of the coal. The stages in the development 

 of the coals from the original vegetal matter through bacterial action, 

 deformative movements of the strata, and igneous intrusions are carefully 

 treated. Under the head of climatic and atmospheric conditions of the 

 Carboniferous, the author discusses the older hypotheses of a heavy atmo- 

 sphere, rich in carbon dioxide, and the newer view of an atmosphere with 

 a limited fluctuating carbon dioxide content depending upon many factors. 

 A close relation between extensive coal deposits and periods of unusual 

 vulcanism which might be supposed to furnish the necessary carbon dioxide 

 for the plant growth is sought, but no very apparent relation between the 

 two is found. The Carboniferous was not preceded by any very unusual 

 volcanic activity. To supply the carbon for the Coal Measures one would 

 have to look back to the Devonian igneous activity. But in this discussion 

 the author apparently fails to make use of the fact which he recognizes, 

 namely, that much more carbon dioxide enters into the formation of lime- 

 stone than is stored away in coal deposits. When it is considered that the 

 atmosphere has been steadily contributing carbon dioxide to extensive 

 limestone development throughout most of the sedimentary geologic 

 history, the storage of carbon in coal beds at certain horizons in the 

 Carboniferous, Cretaceous, Tertiary, etc., becomes less exceptional in its 



