PETROLOGICAL ABSTRACTS AND REVIEWS 589 



gabbro. Forty-three chemical analyses are given, and in most cases the 

 normative minerals are computed. In the general discussion the 

 characteristics, chemical compositions, normative compositions, the 

 relations of norms to modes, and the classification are considered. 

 Twenty-two pages are devoted to the distribution of the rocks in the 

 Hawaiian Islands and of analogous rocks elsewhere in the world. The 

 writer discusses the Atlantic and Pacific provinces, and the alkalic and 

 calcic series (alkali and alkali-lime series of Rosenbusch), and concludes 

 with a discussion of differentiation in the Hawaiian magmas. 



Cross, Whitman. "On Certain Points in Petrographic Classi- 

 fication," Amer. Jour. Sci., XXXIX (1915), 657-61. 

 An answer to several criticisms of the C.I.P.W. system of rock 

 classification. 



Dalmer, K. Erlduterungen zur geologischen Spezialkarte des 



Kbnigreichs Sachsen. Sektion Treuen-Herlasgriin, Blatt 134. 



2d ed. revised by E. Weise and A. Uhlemann. Leipzig, 19 13. 



Pp. 58, pi. 1. 



Picrite, diabase, granite, quartz-porphyry, mica-porphyrite, various 



contact metamorphosed schists, and sediments are described. 



Daly, Reginald A. Origin of the Iron Ores at Kiruna. Vetensk. 



och Prakt. Undersok. i Lappland. Stockholm, 1915. Pp. 



35, ngs. 4. 



Expresses the view that the "inclusions" of ore in the Kiruna 

 quartz-porphyry, are endogenous, and represent "frozen-in" units of 

 differentiation. The accumulation of such ore-masses by gravity is 

 thought to be the cause for the origin of the main ore bodies. 



Daly, Reginald A. Geology of the North American Cordillera at 

 the Forty-Ninth Parallel. Mem. 38, Dept. Mines. Ottawa, 

 1912. Pp. 840, maps 17, pis. 73, figs. 42. 

 \ Although the date on the title-page of this important memoir is 

 /.912, and the date of transmission 19 10, it was not distributed until 

 1914. In the meantime Daly's Igneous Rocks and Their Origin, which 

 contains a much fuller statement of the theories expressed in chaps. 



