196 



SCIENCE. 



[N. S. Vol. II. No. 33. 



Dr. Norwood's geological work was done 

 between the years 1845 and 1855. He was 

 associated with Dr. D. D. Owen in the Geo- 

 logical Survey of Wisconsin, Iowa and Min- 

 nesota, and was later State Geologist of 

 Illinois. From 1860 to the time of his death 

 (May 6, 1895) Dr. Norwood held a profes- 

 sorship in the University of Missouri, but 

 on account of ill health his active work with 

 that institution ceased in 1880. The paper 

 is accompanied by a portrait and a list of 

 publications. 



The Keweenatvan According to the Wisconsin 

 Geologists. By N. H. Wii-rcHELL. 

 This is the sixth in a series of papers en- 

 titled ' Crucial Points in the Geology of the 

 Lake Superior Eegion.' With the conclu- 

 sions of the Wisconsin Geological Survey 

 concerning the Laurentian and Huronian 

 the author does not essentially disagree, but 

 he criticises the conclusions regarding the 

 Keweenawan and the Upper Cambrian 

 sandstones. It is stated that the Kewee- 

 nawan was introduced by a period of sub- 

 sidence and the deposition of conglomerates 

 and sandstones, and that the great igneous 

 activity of this age was later than these 

 basal clastic rocks ; the opposite view was 

 held by the Wisconsin geologists. The 

 author also brings forward evidence to show 

 that there was not necessarily a long erosion 

 interval (and a consequent unconformity) 

 between the Keweenawan and the Upper 

 Cambrian sandstones, as was held by the 

 Wisconsin Geological Survey. 



Superior Mississippian in Westeini Missouri and 

 Arkansas. By Charles Rollin Keyes. 

 Recent work has shown that the upper 

 Mississippian rocks in western Missouri, 

 which have been regarded as not presenting 

 a series easily parallelized with the typical 

 rocks of this age in the Mississippi valley, 

 are present in both their superior and in- 

 ferior portions. The Burlington limestone 

 is practically the same as at the typical 



localitj', and a typical Kaskaskia fauna is 

 present in the uppermost member of the 

 Mississippian. 



Glacial Notes From the Planet Mars. By E. 



W. Claypole. 



A summary of knowledge concerning the 

 polar caps of Mars, which are believed to 

 be'composed of snow and ice, is presented. 

 It is shown that Mars aifords no evidence 

 in support of the eccentricity theory of 

 glacial cold, though his conditions are at 

 present such as to favor a state of intense 

 glaciation in his southern hemisphere. 



Correlations of Stages of the Ice Age in North 

 America and Europe. By Waeeen Up- 



HAM. 



The series of stages of fluctuating growth 

 and decline of the ice sheets on both sides 

 of the North Atlantic are shown to be nearly 

 alike and probablj^ contemporaneous, so 

 that the names proposed by Chamberlin for 

 the principal American stages are applied 

 also to the European, these names being 

 here given on maps of the glacial drift of 

 each continent. The marginal moraines of 

 each are referred to the Champlain epoch, 

 which was the short closing part of the 

 Glacial period. 



Besides the foregoing articles, this num- 

 ber contains departments of editorial com- 

 ment, reviews of recent geological literature, 

 lists of recent publications in geology, and 

 personal and scientific news. 



NEW BOOKS. 

 The Principles of Physics. Alfred P. Gage. 



Boston and London, Ginn & Co. 1895. 



Pp. ix -I- 634. 

 An Introduction to Chemical Crystallography. 



Andreas Fock. Translated and edited 



by William J. Pope. Oxford, The 



Clarendon Press. 1895. 

 Petrology for Students. Alfred Harker. 



Cambridge, University Press. 1895. Pp. 



viii-t-306. $2.00. 



