40 W. A. Yerwiebe — Correlation of the 



crop in Crawford and Erie counties and consist mostly of blu- 

 ish shales and bluish grey sandstones averaging about 325 feet 

 in thickness. The writer has collected fossils from various 

 parts of this group and these show great affinity w^ith Chemung 

 types. Such characteristic species as Spirifer disjunctus^ Pro- 

 ditctella Boydii^ Hhynchonella contracta are particularly abund- 

 ant. On tracing this group to the east it becomes apparent 

 that it is the marine equivalent of a part of the Catskill ter- 

 rane or more definitely should be classed as upper Chemung. 

 For further details it will be advantageous to consider this 

 formation in conjunction with the following one. 



Ricemlle : This name was given by I. C. White to the inter- 

 val of shales between the first sand of the Yenango oil group 

 and the. overlying Corry (Berea) sandstone. It comprises blu- 

 ish and red shales and shaly sandstones and should be con- 

 sidered an integral part of the underlying oil sand group, being 

 identical in lithology and fossil content. Its thickness is varia- 

 ble, ranging from perhaps 50 feet to over 200 feet. The red 

 beds have not been seen on the outcrop in Crawford or Erie 

 counties ; however they are well evidenced in well records fur- 

 ther south and east. A typical well record showing the litho- 

 logic character of the formation may be found in a paper by 

 the writer on the Berea sandstone of Ohio and Pennsylvania."^ 

 In these red shales we have a connecting link with the Bedford 

 shale of Ohio and the correspondence between these is further 

 substantiated by the paleontologic evidence. 



Much effort and time were spent in an attempt to find a dis- 

 conformity between the liiceville and Berea; however, owing 

 to the few exposures, without success. We can only conjec- 

 ture its existence from a consideration of the variable thickness 

 of the Riceville. The evidence in hand then points to the 

 probability that the Bedford formation finds its continnation in 

 the Eiceville and Yenango oil group of western Pennsylvania. 



Girard shale: Another formation named and described 

 from outcrops in northwestern Pennsylvania is the Girard 

 shale. The name was suggested by I. C. White from its typi- 

 cal exposures along Elk Creek near Girard in Erie Connty.f 

 Here it consists of very thinly laminated, grey and bine shales. 

 The thickness is approximately 225 feet. On the outcrop the 

 formation is easily recognized, because it readily disintegrates, 

 forming talus slopes which at a distance resemble ash heaps 

 very much. As regards fossils the formation seems to be 

 barren with the doubtful exception of fucoid markings. Mr. 

 White in correlating it was not willing to decide the matter on 

 the basis of the evidence then available, but said that it might 



* This journal, vol. xlii, p. 58, 1916. 



t White, I. C. , Pa. 2d Geol. Survey, Kept. Q^, p. 118. 



