286 PETROLOGICAL ABSTRACTS AND REVIEWS 



whole, not as great as those of the other two series and especially the inter- 

 mediate members between the charnockite and the anorthosite are as yet but 

 little studied. 



The series includes charnockite, maugerite, anorthosite, and kyschtymite, 

 and is represented in Canada, Norway, Russia, Saxony, and the type locality 

 of Madras described by Holland. 



The analyses show with a rise in silica a decrease in anorthite and, when 

 this is over 56 per cent, the content of the alkalies, producing microperthites, 

 rises rapidly at the cost of the lime-soda feldspars until the granitic type of 

 the series is reached. 



The uncertain touch in handling this new series is striking evidence 

 of the evils of combining the elements of genesis and composition in a 

 systematic presentation of rocks. Either the integrity of the series 

 rests upon the chemical similitude of its members or in their genetic 

 association. It cannot rest on both as of equal supporting value. From 

 the treatment of this new series by Rosenbusch it is impossible to credit 

 him with a clear concept without charging him with serious defects in 

 revision. The series is introduced incidentally (p. 182) without any 

 forecasting of its existence in the general discussion or in that of the 

 granites where a typical member of the new series (Hypersthene granite 

 from Birkem) is cited as a member of the alkali-lime granites, at least by 

 implication. Moreover, charnockite itself is described briefly (p. 94) 

 without reference to the new series, while the index to the volume itself 

 shows no reference to its discussion on p. 182. That it is possible to 

 erect a new series may be seen from a study of Osann's analysis, since 

 rhyolite, micatrachyte, dacite, amphibole-andesite, aplite, granite, 

 and alaskite show the chemical characteristics assigned to the series, 

 viz., relatively high alumina, lime, and the alkalis, low iron, magnesia, 

 and varying silica. 



The discussion of the Essexites, the Shonkinites, and other "basic 

 alkali" deep-seated rocks has been entirely rewritten and expanded by 

 embodying the results of the studies of Hibsch in Bohemia, Lacroix in 

 Madagascar, and others in different areas. 



The chemical discussion at the end of the chapter on the deep-seated 

 rocks is enriched by the graphic representation of the analyses according 

 to the scheme proposed by Osann and by a short tentative discussion of 

 the molecular character of the magmas. 



The discussion of the dike rocks is little changed from that of earlier 

 editions. A slight modification in terminology from granite porphyry 

 to granito-porpkyritic is noted at the beginning but not consistently 

 followed, and the introduction of granito-porphyritic rocks equal to the 

 alkaline and basic alkaline rocks has been made to improve the symmetry 



