188 The Lower Devonian Deposits of Maryland 



IX. Section at Hancock 



About 1^ miles west of Hancock Station, on the West Virginia side of 

 the Potomac, is the Hancock White Sand Works. Here the Oriskany is a 

 pure white sandstone, sometimes a little gritty. At its most extensive 

 outcrop, known locally as " Lovers Leap," about 130 feet is exposed, the 

 remainder being covered by talus. Some of these sandstone beds are very 

 fossiliferous while others are comparatively barren. 



Beautiful white casts of the following fossils were obtained here: 

 Spirifer arenosus (aa), S. murcliisoni (rr), S. intermedius (rr), Rensse- 

 Iceria marylandica (aa), Beachia suessana (r), Eatonia peculiaris (rr), 

 Plethorhyncha larrandii (rr), Diaphorosioma ventricosum (aa), Plcu- 

 iijceras magnificum (c), P. toi-tiiosum (r), Megamhonia lamellosa (r), 

 Homalo?wtus sj). (tt), Megistocrinns sp. (c). 



The origin of these glass-sand pockets in the Oriskany, of which this is 

 an especially large one, is a matter of interest. The rock is almost pure 

 silica and must have been thoroughly washed at the time of the deposition 

 or by infiltrating waters which have carried away the iron and other im- 

 purities found in the Oriskany elsewhere. It may also be a combination 

 of both methods. Certainly in this region the wave-work must have 

 cleaned the sand to some extent for it is a very white and pure sandstone 

 over a considerable area, i. e., as far west as Tonoloway Hill. Since, how- 

 ever, that portion fit for glass sand is only found in pockets and limited 

 lenses and is much softer than the rest, it seems probable that the perco- 

 lating waters carried away the calcareous cementing material and such 

 other impurities as exist in the rock surrounding these pockets and lenses. 



X, Section at Warren Point, Pennsylvania 

 Both the Helderberg and Oriskany are exposed at this place. Under 

 the south end of the iron bridge over Licking Creek the following short 

 section is shown with the Oriskany-Romney contact.^ 



RoMXEY Formation 



Vertical Total 



Onondaga Memher thickness vertical 



feet thickness 



Black and gray argillaceous and arenaceous shales with a 

 basal conglomerate. Ambocmlia umbonata (r), Rhipidomella 

 cyclas ? (r), Styliolina flssurella (a), Phacops rana (r). 



^ Measured by R. B. Rowe. 



