Reviews — Dr. J. V. Ekden's Chemical Geology. 35 



and range of Mesozoic and Tertiary floras, by Mr. F. H. Knowlton ; 

 and on the conditions governing the evolution and distribution of 

 Tertiary faunas, by Mr. "W. H. Dall. Marine, brackish-water, and 

 freshwater strata are dealt with, and the evidence of the assemblages 

 of fossils that existed under different physical and climatic conditions 

 is discussed in reference to their value in indicating geological time. 



In an account of the environment of the Tertiary faunas of the 

 Pacific coast of the United States Mr. Ralph Arnold points out that 

 " Many of the movements occurring throughout the Tertiary were 

 of local extent, and, for that reason, correlation on a basis of 

 diastrophism, unsupported by palseontologic evidence, is extremely 

 hazardous". 



The correlation of the Cenozoic through its mammalian life is 

 discussed by Professor H. P. Osborn, who remarks that " The sea 

 borders of the United States may be correlated with each other and 

 with those of Eurasia in Cenozoic times through their invertebrate 

 life, but for the vast interior of the American continent we must 

 depend chiefly upon the mammals and in a less degree upon the 

 reptiles, fishes, insects, and plants". 



The Physical Geography of the Pleistocene with reference to the 

 correlation of the formations, is the subject of an interesting 

 article by Professor Salisbury. Mr. D. T. Macdougal then deals 

 with the speculative subject of the Origination of Self-generating 

 Matter and the influence of aridity upon its evolutionary development. 

 Finally Professor T. C. Chamberlin explains Diastrophism as the 

 ultimate basis of Correlation. 



The absence of an index to this volume is unfortunate. 



II. — Pkinciples op Chemical Geology. By James Vincent Elsden, 

 D.Sc, F.G.S. London: Whittaker & Co., 1910. 



rnHE title of this work will recall to the mind of geologists the 

 X ponderous volumes of Bischof, which in their day held a high 

 place in geological literature. Dr. Elsden's book, however, is 

 a small, compact volume, and deals mainly with aspects of chemistry 

 that were not recognized in Bischof's time. It is an exposition of the 

 results attained by physical chemists in so far as they are directly 

 applicable to problems of mineralogy and geology. The subject is 

 treated from the standpoint of the equilibrium law formulated by 

 Le Chatelier in 1884, and in successive chapters such questions as 

 viscosity, diffusion, vapour pressures, eutectics, and crystallization of 

 solid solutions are dealt with. The treatment is necessarily brief, yet 

 the exposition is clear and the numerous references to original papers 

 make the book useful to advanced students who desire a further 

 acquaintance with the subject. 



The services that physical chemistry has rendered to geology in 

 the hands of masters of the science such as Van't Hoff, Ostwald, 

 Tammann, and Roozeboom are very great. In every way the best 

 example of the value of this line of investigation is the work of 

 Van't Hoff and his pupils on the Stassfurt salt deposits. There is 



