REVIEWS 207 



of systems, Proterozoic, Permian, Lower Cretaceous, Miocene, and 

 Oligocene only being absent. Pliocene (Lafayette) is indicated in 

 the legend of the map but not shown on the map itself, and the legend 

 seems to be intended to throw doubt on the validity of the formation 

 in Tennessee. 



Under the designation "Columbia Formation," loess, loam, and loose 

 sand are grouped. This seems to us an unfortunate classification. 

 The "Terrace Deposits" of the map are quite as appropriately classed as 

 "Columbia" as the loess and loam which are so classed. We are of the 

 opinion that the use of the term "Columbia Formation" should be dis- 

 continued (though possibly the term "Columbia Series" may be useful 

 to include all Pleistocene non-glacial formations) . What was originally 

 grouped under the name Columbia included several formations of which 

 the probable equivalents of the Terrace Deposits of this map were a chief 

 member. "Loess" would seem to be an adequate designation of the 

 deposits included under that term, without classing them as Columbia. 

 Their classification as Pleistocene seems- altogether adequate. The 

 loess, of many regions at least, is of very different ages, and all of it 

 does not belong to one formation in the chronological sense. 



The map is distinct and represents sufficient change from its prede- 

 cessors to be welcome. It is accompanied by elaborate explanatory 

 legends and by four cross-sections which represent well the structure 

 of the formations in the state. 



The map may be had by application to the State Geologist, Nash- 

 ville, Tennessee. Postage, 8 cents. 



R. D. S. 



Cretaceous Deposits of the Eastern Gulf Region, and Species of Exogyra 

 from the Eastern Gulf Region and the Carolinas. By L. W. 

 Stephenson. U.S. Geol. Surv., Prof. Paper 81, 1914. ' Pp. 

 75, pis. 21, charts 8. 

 In eastern Alabama and Georgia a terrane, previously regarded 

 as forming the eastward extension of the Tuscaloosa series of western 

 Alabama, has been shown by its unconformable relations with overlying 

 formations, lithologic character, and contained plant fossils to be of 

 Lower Cretaceous (Comanchean) age, though probably somewhat 

 younger than the Patuxent. Belonging to the Upper Cretaceous 

 (Cretaceous) of the eastern Gulf region are four formations, Tusca- 

 loosa (regarded as Lower Cretaceous), Eutaw, Selma chalk, and 



