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SCIENCE 



[N. S. Vol. XXV. No. 637 



mental work on the crystallization of rock 

 minerals in the laboratory is reviewed and 

 Doelter's own observations on the precipitation 

 of crystals in molten liquids are noted. 



The question of the order of the eruption of 

 different kinds of rocks at given centers of 

 volcanic activity is treated in the sixth chap- 

 ter. The diverse statements of petrographers 

 as to the order in different regions are noted 

 and the conclusion reached that there is no 

 uniform order which obtains for all regions, 

 but that the succession is highly complex. 



The seventh chapter deals with inclusions 

 in igneous rocks, their character and origin. 

 Assimilation and corrosion are discussed in 

 chapter eight. First the changes effected on 

 minerals crystallized from magmas, and then 

 the effects on rocks in contact with molten 

 magmas. The laboratory production of rocks 

 by experimental means is described in chapter 

 nine, especially the researches of Fouque and 

 Michel-Levy, and those of Morozewicz. 



In the tenth chapter the solidification of 

 volcanic magmas is discussed with reference 

 to the minerals produced under different con- 

 ditions, and also with respect to the order of 

 their separation. Laws affecting the crystal- 

 lization of compounds from solutions are re- 

 viewed, the question of eutectic mixtures is 

 considered, also the effect of undercooling, the 

 melting point of minerals, and the influence 

 of pressure on separation. The production 

 of tuffs and bombs is also discussed. In the 

 eleventh chapter contact metamorphism is de- 

 scribed and its causes and processes discussed. 



The crystalline schists are treated in one 

 chapter of fifty-two pages. Various theories 

 as to their origin are reviewed, chiefly those 

 based on specific researches upon special re- 

 gions or particular occurrences. It will be 

 enough to note the captions under which the 

 subject is treated: Eruptive Gneiss, Gneiss as 

 Altered Granite, Diagenesis, Eegional Meta- 

 morphism, The Chemical Composition of the 

 Rocks, Alteration by Means of Water, Altera- 

 tion by Means of High Temperature, Injec- 

 tion Hypothesis, Dynamic Metamorphism, 

 Chemical Reactions in Solids, Plasticity of 

 Rocks, Lateral Pressure, Connection between 



Metamorphism and Dislocation, Law of the 

 Change of Volume, Mineral Composition of 

 Crystalline Schists, Structure and Texture of 

 Schistose Rocks, Orig^in of Schistosity, Zones 

 of Metamorphism, Objections to a General 

 Application of Dynamic Metamorphism, For- 

 mation of Crystalline Schists by Contact 

 Metamorphism, Comparison of Contact Meta- 

 morphism and Dynamic Metamorphism. 



The thirteenth chapter treats of sediments, 

 their kinds and modes of formation. The 

 major portion of the chapter is devoted to 

 limestone and the formation of dolomite. The 

 last chapter contains a discussion of the pro- 

 duction of chemical precipitates, the deposi- 

 tion of rock salt, gypsum and anhydrite. The 

 works of Bischof, van't Hoff and of Ochsenius 

 are those chiefly cited. J. P. Iddings 



The Origin and Structure of the Boxhury 

 Conglomerate. By George Rogers Mans- 

 field. Pp. 180, 7 pis. Cambridge, Mass., 

 November, 1906. Bull, of the Museum of 

 Comparative Zoology at Harvard College, 

 Vol. XLIX. Geol. Series, Vol. VIII., No. 4. 

 This paper, after a rather lengthy introduc- 

 tion, begins with a forty-five-page chapter on 

 the origin of conglomerates, in which are dis- 

 cussed the various types of conglomerate. The 

 discussion is thorough, and the results, drawn 

 principally from the conclusions and opinions 

 of previous writers in different countries, are 

 tabulated. This digest is of general interest, 

 and is a valuable contribution to the subject. 

 The remainder of the work deals principally 

 with the three Carboniferous basins of Massa- 

 chusetts and Rhode Island — the Boston Basin, 

 which includes the Roxbury conglomerate; 

 the Norfolk Basin, and the Narragansett 

 Basin. The text is essentially a critical re- 

 view of previous publications on these areas, 

 especially of the Boston Basin, which has been 

 studied in great detail by Professor W. O. 

 Crosby. Professor Crosby's work in this re- 

 gion has extended over a period of at least 

 thirty years, and no less than sixteen of his 

 publications are included in the author's 

 bibliography. In view of this fact it is 

 noteworthy that, in the fitnal paragraph of 



