84 The Middle Devonian Deposits of Maryland 



is the best exposure of the Helderberg formation in the Hancock region, 

 showing the faunas of the Coeynians limestone, New Scotland beds and 

 Beeraft limestone of New York. This region has been well described 

 by Dr. Eowe and he has also described the section at the southern end 

 of tlie bridge, which is an especially interesting one as it shows the con- 

 tact of the Oriskany and Eomney with a conglomerate at the top of the 

 Oriskany and another at the base of the Eomney, and called attention 

 to its structural significance. A more detailed section of this locality 

 follows : 



No. 1. On the bank at the eastern side of the bridge and along the 

 side of the highway to the south the upper rocks of the Oriskany sandstone 

 and the succeeding shales of the Eomney formation are shown. Begin- 

 ning at the top of the section these shales as shown by the roadside are 

 somewhat arenaceous, rather coarser than the lower ones, weather to a 

 slightly greenish tint and are in the Onondaga member. There are some 

 fossils here and the following species have been identified : RhipidomelJa 

 cijclas Hall (?), Amhocoelia unihonata (Conrad), Styliolina fissureUa 

 (Hall), Phacops rana (Green), Crinoid segments. 



No. 2. The lowest shales are argillaceous, weather to a slightly 

 gi'oenish tint and contain some quartz pebbles which were probably de- 

 rived from the lower Oriskany conglomerate. 



No. 3. Covered for some 2 to 3 inches; Eomney-Oriskany contact. 



No. 4. At the top of the Oriskany a layer of mainly rather coarse 

 grained sandstone in which are some quartz pebbles. 



No. 5. A conglomerate layer, 2^/2 inches in thickness, containing 

 quite large, smooth, quartz pebbles some of which are 1^2 inches in length 

 and % of an inch in width. 



No. 6. Dark blue, arenaceous limestone in which are bands of grit 

 containing some fair sized quartz pebbles, and conglomerate. Only the 

 upper part of this zone, in which fairly abundant specimens of Oriskany 

 fossils occur in layers, is shown on the eastern side of the bridge; but on 

 the western side is a much better outcrop where between 14 and 15 feet 

 is exposed. The grit and conglomerate layers are also better shown on 

 the western side. 



