62 F\ REPORT OF PROGRESS. E. W. CLAYPOLE. 



Pentamerus is worthy of notice, no specimens having yet 

 been obtained. It should, however, be borne in mind that 

 only one exposure (Clark's mill) has been closely examined, 

 this being the only good one found in the county. 



The Flint shales overlying the Lime shales afford few fos- 

 sils except in one horizon — the White flint These beds are 

 often crowded with casts among which Sp. macropleura, 

 Conrad, and Stropliomena rtigosa, Dalman, are especially 

 abundant. At the base of these shales the bed immediately 

 overlying the black cherty limestones, and perhaps the 

 latter also to some extent, abound with silicified crinoidal 

 joints and may perhaps be an equivalent of the encrinital 

 limestone of New York. There is however nothing in the 

 New York section resembling the immense flint deposit of 

 Perry county. These however are apparently of limited 

 extent, as I found no sign of their presence in Huntingdon 

 county, where, at the Mapleton sand -works, a good section 

 is shown in the tunnel by which the sand is brought out of 

 the quarry. The whole interval there shows only soft shale 

 of different colors, chiefly red and yellow. 



It appears then that with a general resemblance amply 

 sufficient to establish their correspondence, there are num- 

 erous smaller discrepancies such as would be likely to ap- 

 pear at a distance of between 200 and 300 miles from the 

 outcrop in New York. 



No. VII. Oriskany Sandstone. 



This remarkable but variable bed is found in Perry county 

 in almost every place where its outcrop might be expected. 

 Ir forms one of the most conspicuous features of the map, 

 zigzagine back and forth as the various minor folds in the 



C5 O O 



strata bring it to the surface. It nowhere exceeds 20 or 25 

 feet in thickness ; it varies from white through yellow to red, 

 and in hardness from pure sand to a llinty rock. In some 

 places ir is a mass of small white quartz pebbles like white 

 beans ; in others it is a clean sandstone. 



In Pfoutz's valley it is very thin or in some places en- 

 tirely absent. 



Along Sherman's creek it attains its greatest development. 



