Obituary. 419 



as determined by Antevs between Hartford, Connecticut, and 

 the Canadian boundary. 



A ready means is now at hand for a definite chronology of 

 post-glacial time, and our thanks and congratulations are due 

 to Doctor Antevs for his successful results. cs. 



3. A Section of the Paleozoic Formations of the Grand 

 Canyon at the Bass Trail ; bv L. F. Noble. U. S. Geol. Survey, 

 Prof. Paper 131-B, pp. 23-73, pis. 19-25, 4 text figs., 1922.— In 

 this memoir the author brings together in great detail all that 

 he has learned about the Paleozoic sequence — Cambrian, Devo- 

 nian, Mississippian, Peiinsylvanian, and Permian — of the 

 marine and continental strata in the Grand Canyon of the 

 Colorado River, during the years 1914, 1916 and 1920. Various 

 sections are described from Bass Trail eastward for 35 miles, 

 and all of the zones and sections correlated into a generalized 

 sequence having a thickness of 4014 feet, besides 506 feet of 

 Triassic formations. The Grand Canyon should be the Mecca 

 for all stratigraphers, and the worshippers at this grandest of 

 Nature's shrines will find guidance and inspiration in Doctor 

 Noble's careful study of the sediments deposited here by an 

 epeiric sea, from shore to deeper water. c. s. 



4. Essentials for the Microscopical Determination of Rock- 

 Forming Minerals and Rocks in Thin Sections: by Albert 

 Johaxxsex. Pp. 53, with 24 text figures. Chicago, 111., 1922. 

 (The University of Chicago Press, $2.00.) — This work is a 

 revision of the author's well-known laboratory manual, "A Key 

 for the Determination of Rock-forming Minerals in Thin 

 Sections,'** which was published in 1908. The new edition 

 appears in a markedly different format, being now in quarto 

 instead of octavo, and by rearrangement of the determinative 

 tables it has been very notably reduced in bulk — from 542 pages 

 to 53. The descriptions of the individual minerals have been 

 slightly condensed. Brief notes on the modes of geologic 

 occurrence have been added, and the diagnostic differences 

 between minerals of somewhat similar optical properties are 

 more adequately emphasized. A summary exposition of the 

 author's quantitative mineralogical classification of igneous 

 rocks has also been added. 



Adolph Kx;opf. 



5. The Rocks of Mount Everest. — The efforts of the members 

 of the Mt. Everest expedition of 1922 to reach the Summit of 

 the mountain have already been fully given in the public 

 press. That it was found possible to reach an altitude of 27,300 

 feet, with the aid of oxygen, is sufficiently noteworthy. It is 

 still more interesting that a third expedition is already being 

 tentatively considered and a greater degree of optimism is 

 felt bv the climbers as to ultimate success than after the effort 



