Geology and Mineralogy. 151 



Professor Geikie appeals to the occurrence of boreal and arctic 

 shells in Quaternary marine deposits as proving that glacial con- 

 ditions have been for some reason associated with submergence 

 rather than with emergence of the land. " Each glacial epoch," 

 he says, " was preceded and accompanied by partial submergence 

 of the land. 1 '* We query whether the correlation of the deposits 

 has been worked out with sufficient accuracy to exclude the view 

 of LeConte, that a glacial climate may have been preceded and 

 occasioned by elevation, but may have continued after consider- 

 able subsidence had taken place, the various effects lagging 

 behind their causes. f It may be remarked parenthetically that 

 Professor Geikie no longer holds to a deep Quaternary submerg- 

 ence of Britain, regarding the marine shells of Moel Tryfaen as 

 " erratics."! 



The co-existence of northern and southern forms of vegetation 

 in interglacial deposits is appealed to as showing that the climate 

 in such epochs was exactly what the eccentricity theory requires 

 — a climate of mild winters and cool summers.§ 



Professor Geikie refers to the estimates of Gilbert and Win- 

 chell on the recession of Niagara and St. Anthony's Falls, but 

 rejects them as unreliable. | 



The relation ol the succession of geological events in the Qua- 

 ternary to the history man, is briefly treated. It is maintained 

 that paleolithic man and the southern pachyderms with which he 

 had been associated retired from England before the epoch of 

 the Second Mer de Glace [the third of the five glacial epochs in 

 the table which we have quoted], and never returned to Britain 

 or northwestern Europe. 1 



In conclusion, we would express our regret that a book of over 

 four hundred octavo pages, containing so much that is interest- 

 ing and valuable of fact and theory, should not be provided with 

 an index. 



13. Economic Geology of the United States; by Ralph S. 

 Taer (Cornell University), pp. 509 (Macmillan & Co.), J 894. — 

 This is the latest of the attempts to popularize the facts of 

 geology by presenting them from the point of view of local dis- 

 tribution and commercial value, and from this point of view is 

 well adapted for the American students. Economic geology was 

 introduced as a special feature at Cornell University first with 

 the use of David Page's Economic Geology, or Geology in its 

 relations to the Arts and Manufactures (1874), a year or two later 

 an elaborate synopsis of lectures for the course was prepared by 

 T. B. Comstock. Later (1886) Samuel G. Williams, now Profes- 

 sor of Pedagogy at Cornell, prepared Applied Geology (Apple- 

 ton's) on the same lines. In 1893 appeared Ore deposits of the 

 United States, by James F. Kemp (now Professor of Geology at 

 Columbia School of Mines), (The Scientific publishing company) 

 1894, a valuable work for others than elementary students. The 



* Page 321. \ Eull. Geol. Soc. Am., iii, 329. % Page 173. 



§ Page 385. || Page 286. \ Page 243. 



