RECENT ADVANCES IN SCIENCE 211 



Schuchert, C, On the Carboniferous of the Grand Canyon 

 of Arizona, Amer. Journ. Sci. 191 8, 45, 347-61 ; On the Cam- 

 brian of the Grand Canyon of Arizona, ibid. 362-9. 



Geologia do Estado do Parana (Brazil), Bol. Min. d. Agric. 

 Indust. e. Comm. Anno V., N. 1, 191 6, Rio de Janeiro, pp. 



67-143. 



Igneous Rocks. — Washington, H. S., Chemical Analyses of 



Igneous Rocks published from 1 884-1913 inclusive, with a 



Critical Discussion of the Character and Uses of Analyses, 



U.S. Geol. Survey, 191 7, Prof. Paper 99, pp. 1201. 



The igneous mass of Cuttings ville (Vt.) is shown by J. W. 

 Eggleston to be a composite stock, consisting of various 

 syenites with essexite, arranged in a roughly concentric manner 

 (Amer. Journ. Sci. 1918,45, 377-410). The order of eruption 

 was from basic to acidic ; and this is also the general order 

 in the associated dyke rocks. This intrusion is correlated 

 with the numerous small bodies of alkaline igneous rocks 

 which occur scattered throughout the Quebec-New England 

 region. 



J. P. Iddings and E. W. Morley have published thirty 

 new analyses of igneous rocks from the islands of Tahiti, 

 Moorea, and the Society group (Proc. Nat. Acad. Sci. 191 8, 

 4, 1 10-17). Each island is a profoundly-eroded volcano con- 

 sisting mainly of basaltic lavas rich in olivine and augite, which 

 are occasionally accompanied by trachytes and phonolites. 

 In two of the volcanoes deep erosion has exposed plutonic 

 cores of gabbroic and theralitic rocks, and, in another case, 

 syenites and nepheline-syenites. 



Sedimentary Rocks. — Grabau, A. W., Problems of the 

 Interpretation of Sedimentary Rocks, Bull. Geol. Soc. Amer. 



191 7, 28, 735-44- 



Barrell, J., Rhythms and the Measurement of Geologic 

 Time, ibid. 745-904. 



Kindle, E. M., Diagnostic Characteristics of Marine 

 Clastics, ibid. 905-16. 



Blackwelder, E., Characteristics of Continental Clastics 

 and Chemical Deposits, ibid. 917-24. 



Shaw, E. W., Significance of Sorting in Sedimentary Rocks, 

 ibid. 925-32. 



Vaughan, T. W., Chemical and Organic Deposits of the. 

 Sea, ibid. 933-44- 



