RECENT ADVANCES IN SCIENCE 221 



minations, of tonalite and dioritic gabbro from the crystalline 

 basement of Viti Levu, and of numerous lavas from the whole 

 archipelago. These include various types of basalt, andesite, 

 and rhyolite. Foye remarks the association of hypersthene 

 and hornblende in the lavas of Vanua Levu, and suggests that 

 these minerals are due to the retention of magmatic water in 

 submarine flows owing to the rapid formation of a flexible im- 

 pervious skin. Monoclinic pyroxene, on the other hand, 

 should be formed at open vents, in which there is a free escape 

 of magmatic gases. 



A short paper by Friedlander (" Gesteine von Sakurashima," 

 Zeitsch. f. Vulc. 191 8, 4, 202-3) is notable for six new chemical 

 analyses of lavas and ashes from the recent eruption of Sakura- 

 jima, Japan. 



Origin of Sedimentary Rocks. — The great work by L. Cayeux, 

 " Introduction a l'Etude Petrographique des Roches Sedimen- 

 taires " (Mem. Carte Geol. de France, 19 16, pp. 524, and Atlas 

 of $6 plates) will prove of the utmost value to petrographers. 

 It is divided into three parts : 1. Methods of analysis of sedi- 

 mentary rocks, with special consideration of microchemical 

 methods ; 2. Diagnostic of the constituents of sedimentary 

 rocks ; 3. Study of the microstructure of organisms considered 

 as constituent elements of sedimentary rocks. This last is done 

 in great detail, and illustrated by many magnificent plates. 



Staurolite is the principal mineral of heavy residues from 

 the Bunter Pebble Beds of Nottinghamshire, and T. H. Burton 

 (Quart. Journ. Geol. Soc. 191 8, 73, pt. 4, 328-39) therefore be- 

 lieves that Scotland supplied the bulk of the heavy constituents, 

 a north-eastern river and its tributaries being postulated as the 

 means of transport. 



W. H. Bucher brings forward evidence to support the 

 view that oolites and spherulites are due to the change of at 

 least one constituent from the emulsoid to a solid condition 

 (Journ. Geol. 191 8, 26, 593-609). The difference between 

 radial and concentric structures depends on the amount of 

 other substances simultaneously precipitated, and mechanically 

 entangled in the growing concretion. If the substance is 

 relatively pure the structure is predominantly radial (spheru- 

 litic). If other substances are precipitated in quantity the 

 structure tends to be concentric (oolitic). These views are 

 based on the important work of Schade relative to the origin 



