114 Scientific Intelligence. 



II. Geology and Xatcral History. 



1. Conemaugh formation in Ohio ; by D. Dale Coxdit and 

 Clara Gould Mark. Geol. Surv. Ohio, 4th series, Bull. 17, 

 363 pages, 16 plates, 1912 [not received at New Haven until 

 July, 1913]. — This excellent work, a model in stratigraphy, 

 describes the general and detailed sequence with the local 

 faunas of the Conemaugh formation throughout eastern Ohio. 

 The Conemaugh lies high in the Pennsylvanian system and has a 

 thickness varying between 355 and 500 feet. The irregular 

 deposition of the various sandstones and their channeling through 

 the other deposits, in the main of mai'ine waters, and the pecu- 

 liar limestone " desiccation conglomerates " are clearly brought 

 out. The fossils of the various limestones have been kept apart 

 and carefully determined and tabulated by Miss Mark. The 

 plates of fossils are the work of Mr. Barkentin. The total num- 

 ber of Conemaugh named species is 162, of which 12 are new. 

 The many diminutive bivalves and gastropods and the abundance 

 of Fusulina are features of these faunules. 



The Conemaugh "consists mostly of sandstone, sandy shale 

 and clay, much of which has a reddish brown color. Coal seams 

 and limestones are few and thin. All of the beds are character- 

 ized by lack of persistence, and vaiy greatty as to thickness and 

 appearance from place to place. Local erosion planes and uncon- 

 formities of small magnitude are extremely abundant and occur 

 at all horizons. These hiatuses are shown by conglomerates and 

 truncated strata. Frequently the material of the conglomerates 

 can be traced to some nearby fossiliferous limestone bed or coal 

 seam. 



" Much of the lower half of the Conemaugh formation is of 

 marine origin and has a number of fossiliferous horizons. The 

 highest fossil-bearing beds, lying a little above the middle, mark 

 the final invasion of the sea into the Appalachian basin. All 

 overlying strata lack forms of undoubted marine origin ; their 

 fossils being mostly plant remains, certain minute fossils, such as 

 Sj?irorbis, ostracods and gastropods, generally regarded as fresh- 

 water, together with occasional fish, amphibian and reptilian 

 bones. Insect remains are sometimes found well preserved in the 

 shales. The marine limestones of the lower half of the formation 

 are the most persistent and lithologically uniform beds, but even 

 these have suffered contemporaneous erosion and locally failed 

 to form, owing to unfavorable conditions, such as the presence of 

 shoals in the sea and continuous sedimentation from rivers "(15). 



" It is undetermined whether the retreat of the sea subsequent 

 to the formation of each fossiliferous limestone was due to eleva- 

 tion of the region, or whether there was a progressive subsidence 

 so pronounced at times as to produce a temporary encroachment 

 of the sea with intermittent pauses of sufficient length to permit 



