208 REVIEWS 



Ripley. The first, consisting of irregularly bedded sands, clays, and 

 gravels, has an estimated thickness of i ,000 feet and rests unconf ormably 

 on a basement of Paleozoic metamorphics, and in the east on Pre- 

 Cambrian crystalline rocks and in part on Lower Cretaceous. The 

 Eutaw formation, somewhat similar to the Tuscaloosa in lithologic 

 character, is believed to be entirely marine, though much of the formation 

 was doubtless laid down in very shallow water. It is 400-500 feet thick, 

 rests conformably on the Tuscaloosa, and is overlain conformably in 

 part by the Selma chalk, and in part by the Ripley formation. The 

 Selma chalk consists mainly of more or less argillaceous and sandy 

 limestones rendered chalky by their large content of foraminiferal 

 remains. It is abundantly fossiliferous in certain portions, yielding 

 large numbers of the Exogyra described in the latter portion of the 

 paper. The Selma grades into the sandy member of the Tuscaloosa, 

 and the clastic beds of the Ripley formation when followed along the 

 strike. A thickness of 930 feet of the chalk formation has been measured 

 in western Alabama. The Ripley formation, 250-350 feet in thickness, 

 consists typically of calcareous and glauconitic sands, sandy clays, and 

 impure limestones and marls of marine origin. It extends through parts 

 of the Gulf states from southern Illinois to Georgia. A study of the 

 faunas of the various formations is detailed, and correlations with other 

 Cretaceous regions indicated by chart. 



A description of the genus Exogyra, which includes three species 

 with two varieties, constitutes the second portion of the paper. 



R. C. M. 



The Jurassic Flora of Cape Lisburne, Alaska. By F. H. Knowlton. 

 U.S. Geol. Surv., Prof. Paper 85, Part D, 1914. Pp. 25, pis. 4. 

 The Jurassic of the Cape Lisburne area is estimated to have a very 

 great thickness, 15,000 feet, and contains from 40 to 50 coal beds which 

 range in thickness from 1 or 2 feet to over 30 feet. Plant collections 

 from this area show 1 7 species of well-defined Jurassic types. The close 

 similarity or identity of a number of forms with species from eastern 

 Siberia and Mongolia is noteworthy. The flora indicates a warm- 

 temperate or subtropic climate and the geographic range, especially into 

 the Arctic and Antartic, is suggestive of the uniform mildness of the 

 Jurassic earth-climate. 



R. C. M. 



