640 PETROLOGICAL ABSTRACTS AND REVIEWS 



contemporaneous with the faulting of the region. Pleistocene formations lie 

 directly upon the Pre-Cambrian, and consist of fluvioglacial deposits, till, 

 clays, and lake sands. 



QuiRKE, Terence T., and Finkelstein, Leo. "Measurements 

 of the Radioactivity of Meteorites," Amer. Jour. Sci., XLIV 

 (1917). 237-42. 

 Gives the radium content of twenty-two meteorites not previously deter- 

 mined. It is found that the average stony meteorite is considerably less radio- 

 active than the average igneous rock, probably less than one-fourth that of 

 an average granite, and that the metallic meteorites are almost free from 

 radioactivity. 



Reinheimer, Siegfried. Der Diorit vom Buck bei Lindenfels im 

 Odenwald mit einem Anhang uber einige mikroskopische 

 Methoden. Inaug. Dissert., Heidelberg, 1920. Pp. 62,, Figs. 8, 

 Photo. PI. 3. 

 Two "diorites" and a gabbro are described. No modal percentages 

 are given, but in general it may be said that the main rock from the Buch 

 consists of more amphibole than plagioclase with accessory biotite and a 

 little quartz. The plagioclase is zonal with cores AbiaAngg and outer 

 zones Ab 40-46 An6o-s4- There is a pale to colorless amphibole and one 

 that is green, the latter usually surrounding the former. The author 

 says a "gabbro tendency" is shown, and that diallage is proxied by an 

 amphibole of similar chemical composition. The second rock, from 

 Kreuzer's quarry, near Winterkasten, is similar, although generally the 

 amphibole and plagioclase are in equal amounts. The feldspar is 

 approximately AbiyAnga, biotite is rare, and quartz is wanting. The 

 third rock from near Laudenau differs from the other two. It is de- 

 scribed as a gabbro of the type of the Scandinavian hyperites. The dark 

 minerals consist of green amphibole poikilitically intergrown with plagio- 

 clase, and diallage and olivine. The plagioclase is AbgAugi. Since 

 the plagioclase in all of the rocks is labradorite to bytownite, the reviewer 

 would call all the rocks gabbro (amphibole gabbro) in spite of the state- 

 ment of the author that the magma must have been poor in lime. (No 

 chemical analyses are given.) 



Associated with these rocks are certain diaschistic rocks, among them 

 diorite-pegmatite, schlieren of "needle-diorite," and beerbachite. 



In the Appendix the determination of refractive indices in cleavage 

 fragments of amphibole by the immersion method, and the determination 

 of 2V with the Federow stage are discussed. 



