606 abstracts: geology 



GEOLOGY. — The fauna of the Wewoka formation of Oklahoma. G. H. 

 GiRTY. U. S. Geol. Survey Bull. 544. Pp. 353, with 35 plates. 

 1915. 

 This report is pur3ly paleontologic in treatment and had its inspi- 

 ration partly in the character and fine preservation of the fossils that 

 occur in the Wewoka formation. These circumstances have per- 

 mitted the recognition of a number of new genera and species. The 

 Wewoka formation is one of the Pennsylvanian formations of Okla- 

 homa and is exposed in the Wewoka and Coalgate quadrangles. It 

 consists of alternating banks of shale and sandstone, about 700 feet 

 in all. The fossils occur in the shale beds from which they weather 

 free. In preservation they are unusual, the lime carbonate of which 

 they were originally composed being replaced by a compound of lime, 

 magnesia, and iron. As at present known, the Wewoka fauna con- 

 tains about 150 species, all of which are described and figured in this 

 report. Brachiopod types are relatively few, on the other hand, pele- 

 cypods and gastropods are relatively numerous, and the cephalopods 

 are represented by an unusually larg3 and interesting group of species. 

 A tentative assignment is made of the Wewoka formation to about 

 the position of the Fort Scott limestone of the Kansas section. 



G. H. G. 



GEOLOGY. — Reasons for regarding the Morrison as. an introductory 

 Cretaceous formation. Willis T. Lee. Bull. Geol. Soc. Amer. 

 26: 303 314. 1915. 



The Morrison formation contains bones of dinosaurs which correlate 

 it with dinosaur beds in the Potomac group of the Atlantic Coast, 

 with the Wealden of Europe, and with certain dinosaur beds in east 

 Africa. Marsh, who described the Morrison dinosaurs, believed that 

 they indicated Jurassic age. Later the Potomac and Wealden beds 

 were classed as Lower Cretaceous; the dinosaur beds of east Africa are 

 interstratified with sedimentary rocks containing marine inverte])rates, 

 which, on preliminary examination, seem to indicate Lower Cretaceous 

 age. There is therefore a paleontologic basis for referring the Morrison 

 formation to the Lower Cretaceous. The present paper deals, how- 

 ever, mainly with physical features, which also support the reference 

 of the formation to the Lower Cretaceous. 



The problem of classification is considered from the diastrophic 

 viewpoint. The physical relations of the Morrison to other formations 

 are described and an attempt is made to visualize the physiographic 

 conditions under which the formation probably developed. It is shown 



