Maryland Geological Survey 189 



^ „ Vertical Total 



ORISKAXY FORxMATION thickness vertical 



feet thicltness 



Dark blue arenaceous limestone with bands of fine conglom- 

 erate or grit. These bands are sometimes several inches in 

 thickness and consist of coarse sand with calcareous cement. 

 At the top are 5 or 6 inches of coarse heavy conglomerate, with 

 large smooth quartz pebbles. Rcnsselwria marylandica (r), 

 Spirifer murchisoni (r) , Plethorhyncha barrandei (r) 13.0 18.0 



Dark blue limestone with layers of black chert 5.0 5.0 



Covered. 



Thickness of Oriskany formation exposed 18.0 



This is the best exposure of the Oriskany-Romuey contact to be seen in 

 this region, and adds considerable to the evidence we already have of a 

 temporary land area at the close of the Oriskany. The conglomerate at the 

 top of the Oriskany was formed when the land was rising and the basal 

 conglomerate at the bottom of the Romney was formed while the land 

 was sinking at the beginning of Eomney deposition. The upper conglom- 

 erate of the Oriskany was only partially destroyed by erosion during its 

 emergence and pebbles derived from this upper conglomerate are found 

 for several feet in the base of the Eomney. 



On the north side of the creek about one-quarter of a mile east of tlie 

 north end of the bridge the same succession is shown in several small 

 abandoned quarries. The section ' there is as follows : 



RoMNEY Formation 



Vertical Total 

 Onondaga Member thickness vertical 



feet thickness 

 Black and gray argillaceous shale. 

 Covered. 



Massive coarse conglomerate with large pebbles. Base of the 

 Romney 0.5 65.0 



Oriskany Formation 

 Massive coarse conglomerate, with large smoothly worn 



quartz pebbles, containing Oriskany fossils 1.5 64.5 



Massive light gray limestone with bands of conglomerate or 

 grit near bottom. Conglomerate bands are several inches in 

 thickness and consist of small pebbles and coarse sand. Spirifer 

 arenosus (r), S. murchisoni (c), Meristella lata (aa), M. 



Measured by R. B. Rowe. 



