Geology and Mineralogy. 469 



sive, and carefully wrought out work is a treatise on applied 

 stratigraphy as it relates to the salts of geologic deposits, 

 including the nitrates, phosphates, borates, and similar 

 compounds. ■ ' The emphasis is laid upon the geological relation- 

 ships of these deposits, and the chief endeavor has been to set 

 forth our present understanding of the conditions under which 

 such deposits are formed. To this end, the first volume is devoted 

 to a study of deposits now forming or which have but recently 

 been formed, and of the physical conditions which control such 

 deposition" (ix). Among the more interesting of the eighteen 

 chapters are : III, The sea as a source of saline deposits ; V, 

 Sea margin deposits of salts; IX, Connate salts, their origin 

 and method of concentration ; and XII, Playa deposits of complex 

 salts, c. s. 



6. Text Book of Geology : Part I, Physical Geology; by the 

 late Professor Louis V. Pirsson. Eevised Edition. New York, 

 1920 (John Wiley and Sons).— The Text Book of Geology by 

 Pirsson and Schuchert first appeared in 1915 and immediately 

 won favor as a class-room text book. It is now used in over 

 fifty-eight colleges, Part I, Physical Geology, because of its 

 subject matter, is obviously more widely used, and over fifteen 

 thousand copies of the first edition have been sold. 



In the revised edition of Part I, much of the knowledge 

 contributed to the subject of Physical Geology since the original 

 writing of the book, has been added, and the volume is now 

 up-to-date. Other parts have been thoroughly revised, and some 

 of the text and illustrations eliminated. Alterations in defini- 

 tions and headings are also noticeable. Many of the changes 

 are the result of the author's experience in using the book as a 

 class-room text; others embody suggestions and criticisms from 

 the author's acquaintances among teachers of Physical Geology. 



Among the parts in which revision has produced great 

 improvement, might be mentioned: the work of stream erosion 

 and the resulting topographic forms ; structure and form of the 

 earth ; structures of sedimentary rocks ; fractures and faulting ; 

 and the origin and history of mountains. The classification of 

 ore deposits has been entirely revised. The parts dealing with 

 the relation of stream velocity to transportation and the origin 

 of coral reefs still leave a little vagueness in the student 's mind. 



The unusually even balance of the book and its satisfactory 

 scope have been maintained, and give it a preeminent place as 

 being particularly suitable for a class room text-book. 



Alan M. Bateman. 



7. United States Geological Survey; George Otis Smith, 

 Director. — Recent publications are noted in the following list 

 (see earlier, vol. 49, pp. 448-450). 



Topographic Atlas. — Forty-one sheets. 



Professional Papers. — No. 108. J. The Flaxville Gravel; by 

 A. J. Collier and W. T. Thom, Jr. Pp. 16. 



