REVIEWS 87 



We may therefore conclude (1) that the temperature conditions governing 

 the fauna of the Maryland Chesapeake were those of the temperate rather than 

 the boreal or subtropical faunas of the present coast; and (2) that the temper- 

 ature of the Chesapeake embayment was on the whole somewhat warmer than 

 at present. This is what the genera represented also indicate. Between the 

 several horizons of the Maryland Chesapeake there is but very slight indica- 

 tion of any temperature difference; so far as there is any, it points toward a 

 progressive but slight cooling of the water from the Calvert to the St. Mary's; 

 while the subsequent Pliocene was doubtless accompanied by a change in the 

 opposite direction, a rise of temperature being indicated by the changes in the 

 fauna. 



H. S. W. 



Preliminary Report on the Geology 0} the Arbuckle and Wichita 

 Mountains, in Indian Territory and Oklahoma. By Joseph A. 

 Taff. With an Appendix on Reported Ore Deposits of the 

 Wichita Mountains, by H. Foster Bain. (Professional Paper 

 No. 31, U. S. Geological Survey.) 



This paper treats of the geology and physiography of the mountains 

 named in the title. In both mountain regions there is a core of pre-Cambrian 

 igneous rock. These rocks are much the same in both regions. The 

 principal varieties in the Arbuckle Mountains are granite, quartz-monzonite, 

 aplite, granite-porphyry, and diabase. In the Wichita Mountains gabbro 

 is present, besides most of the above. 



The lowest sedimentary rocks of the Arbuckle Mountain region are 

 referred to the Middle Cambrian, and the Ordovician, Silurian, Devonian, 

 Mississippian, Pennsylvanian, Permian, and Cretaceous systems are all 

 represented. The successive formations are conformable up to the top 

 of the Mississippian. There are unconformities between the Mississippian 

 and the Pennsylvanian, between the Pennsylvanian and the Permian, and 

 between the Lower and Upper Cretaceous. The rocks have been con- 

 siderably deformed and displaced by folding and faulting. 



In the Wichita Mountains the oldest sedimentary rocks are likewise 

 referred to the Middle Cambrian. The other systems represented are the 

 Ordovician and the Permian. The intervening Silurian, Devonian, and 

 Carboniferous beds are supposed to be buried by the Red Beds. The 

 structure of the Wichita Mountains is comparable to that of the Arbuckle 

 Mountains; that is, the beds are deformed both by folding and faulting. 



The physical history of the region is outlined as follows: The mid- 

 Carboniferous (Mississippian?) rocks were uplifted and folded, resulting 



