REPORT OF THE STATE PALEONTOLOGIST 1902 981 



known as the Shenango conglomerate. It with the associated 

 Shenango shales is probably the equivalent of this Knapp 

 formation. 



The coarser part of this formation is usually a loosely ce- 

 mented conglomerate with small well smoothed quartz pebbles 

 of flattened discoidal shape that only in places becomes massive. 

 It is frequently highly limonitic and in most places where exam- 

 ined was fossiliferous. The fossils consist of marine inverte- 

 brates aud plant stems of various kinds. The shales are sandy 

 and olive-green or rusty brown and in several places have been 

 found to contain marine invertebrates. 



The most eastern exposure of these beds is found at Knapp's 

 Creek Station. Here there are two coarse beds separated by a 

 varying thickness of shale. In the gutter beside the road lead- 

 ing from Knapp's Creek Station down into the head of Fourmile 

 creek, in the interval from 20 to 40 feet below the station level, 

 is found a thin bedded gritty to pebbly sandstone heavily 

 charged with iron and containing marine invertebrate fossils. 

 The layers are separated by partings of blue clay shales. A few 

 hundred yards west of the station along the electric road just 

 before reaching the summit there is a second sandstone about 

 40 feet higher than the first one, the interval between being 

 occupied by sandy ferruginous shales. This sandstone is hard 

 and gray and rings under the hammer. It is bedded in layers 

 a few inches thick, some of which contain a few pebbles. The 

 layers are separated by ferruginous sandy shales. It is also 

 fossiliferous bearing among other forms Syringothyris. Above 

 it are perhaps 20 feet of shale before the base of the Olean is 

 reached. Beyond the summit one passes down through the 

 same succession in reverse order, the upper sandstone being 

 about 5 feet thick and more conglomeritic, the underlying 

 shale being 20 feet thick and the lower coarse bed consisting of 

 20 feet of thin conglomerate and sandstone interbedded with 

 shale, the pebbles being chiefly of wheat grain to coffee grain 

 size. Both beds are again fossiliferous. These beds — specially 

 the upper one — are found exposed at intervals along the ridge 

 westward nearly to Harrisburg. At Harrisburg and to the 

 northwest they have been cut out and several small areas of 



