176 



Scientific Intelligence. 



exposures of a continuous series of beds ; sandstones and shales 

 and interbedded limestones, of 3250 feet thickness. An erosional 

 unconformity limits them below, somewhere in the lower part of 

 the Upper Carboniferous, and the uppermost formations are 

 regarded as Permian. 



Forty-seven distinct formations are recognized, giving an aver- 

 age of about seventy feet to a formation. No attempt is made 

 by the author to form more comprehensive divisions of the whole, 

 as was done by Haworth and by Prosser, since the sedimentation 

 is found to be continuous, oscillating between sets of dominantly 

 calcareous beds and sets of beds dominantly shaly, the fossils 

 occurring more richly in the limestone or calcareous formation. 

 " The evolution of the latest from the earliest faunas" is said, 

 by Grirty, to be " without marked interruption at any point so 

 that subdivisions appropriate for recognition are not clearly 

 apparent." No classification of the beds seems to be especially 

 favored by the evidence of invertebrate paleontology. 



David White reports on the Plants from the Kansas beds 

 and finds the majority of them typical Coal Measure (Pennsyl- 

 vanian) species, while those from the Marion and Wellington 

 formations at the top of the section, identified by Sellards, 

 indicate Permian age. h. s. w. 



Folio. No. 94. Brownsville-Connellsville folio, Pennsylvania, 

 by Marius R. Campbell. This geological map and its explana- 

 tion is an admirable example of the thorough work produced by 

 the Survey. The region covered is in southwestern Pennsylvania, 

 in the midst of rich coal and gas fields. The survey is based 

 upon triangulation surveys, and topography of the surface as well 

 as the underground structure are elaborated in detail. Numerous 

 stratigraphic sections of mines (92 are figured and described) are 

 given and the productive horizons of numerous gas wells deter- 

 mined. The classification of the formations is the usual one, with 

 the thickness for this region as follows, viz : 



? Permian 



Dunkard 



{ Monongahela 



t} i • ) Conemauerh 



Pennsylvanian -< A11 , & 

 J Allegheny 



[Pottsville sandstone 



»*■'•'•• S Mauch Chunk 



Mississippian \ ^ 



rr ( rocono 



300' 



310-400' 

 600' 

 280' 

 150' 



150' 

 400' 



The Pocono sandstone is at its top developed into a siliceous 

 limestone. In the midst of the Mauch Chunk, the Greenbriar 

 limestone is developed as a lentil from to 30 feet thick, fossil- 

 iferous ; it is shown to be of Chester age. An unconformity is 

 recognized at the base of the Pottsville, the lower member of 

 which is believed to represent the Conoquenessing sandstone. 

 In the Conemaugh formation a crinoidal limestone (the Ames 

 limestone), four feet thick, is seen below the Morgantown sand- 

 stone. 



