468 PETROLOGICAL ABSTRACTS AND REVIEWS 



While exact and detailed descriptions may seem tedious in an address, 

 it would be desirable in printed descriptions of new types of rocks 

 that they be made as complete as possible and that the relative amounts 

 of the different constituents be stated. For such rocks, clear-cut 

 definitions should be given. 



The paper is a well-written summary of what is known of the vol- 

 canic rocks of Victoria, and one is always thankful for contributions 

 containing careful analyses and complete bibliographies. 



Albert Johannsen 



Watson, Thomas L. "Intermediate (Quartz Monzonitic) Char- 

 acter of the Central and Southern Appalachian Granites," 

 Bull. Phil. Soc, Univ. Va., I (1910), 1-39. 



By comparing the analyses of granites from different parts of the 

 Appalachian region, the author finds that they are, in general, of mon- 

 zonitic character, the soda being molecularly equal to or greater than 

 potash. Comparing the western granites with the Appalachian rocks, 

 he finds that "the eastern type shows stronger granite affinities and the 

 western type stronger quartz diorite affinities." In general the granites 

 of the eastern region are of similar composition, containing acid oligo- 

 clase and some albite in addition to potash feldspar; the ratio aver- 

 aging 1.88 to 1. All of the granites, from Alabama to New England, 

 as well as the subsilicic gabbros, diabases, pyroxenites, and peridotites, 

 "have been derived from a common parent body of magma intruded, 

 in most cases, at different times," says the writer. The age of the 

 massive granite is stated to be early or later Paleozoic, while the gran- 

 ite-gneisses (gneissoid-granites) are pre-Cambrian. 



Numerous analyses, all of them partial, are given. 



Albert Johannsen 



