24 CHARLES S. PROSSER 



seen. On the ridge to the west is the Oriskany sandstone, dipping 

 to the east, as shown in Rocky River and on the highway from the 

 west perhaps one-sixth of a mile north of this locaHty. These 

 shales contain the diagnostic species — Liorhynchus limitare (Van- 

 uxem)— of the Marcellus shale and agree fairly well lithologically, 

 as far as exposed, with those referred to the Marcellus shale in the 

 Baltimore and Ohio railroad cut at the 21st Bridge, Maryland; 

 consequently, they are referred to the Marcellus member of the 

 Romney formation. 



The valley to the east of this ridge along Patterson Creek is 

 presumably composed of the Romney shale, which is probably in 

 a small syncline. The steep wooded ridge to the east of Patterson 

 Creek is the one in which occurs the first railroad cut east of Patter- 

 son Depot. The Patterson Creek Road was followed fully two 

 ■miles from the station, and after the first exposure of the black 

 Marcellus shales they are seen at frequent intervals at the roadside. 

 The more southern shales examined, however, were rather coarser, 

 somewhat more arenaceous, and less fossiliferous. The greater 

 part of the Marcellus is slightly arenaceous and with less clay than 

 is found in the exposures on the Williams Road to the northwest 

 in Maryland, and the shales do not disintegrate so readily. 



On Plum Run, two miles above Patterson Depot and below 

 Mr. Robinson's house, are coarse, unfossiliferous, arenaceous shales 

 varying to fairly thin-bedded sandstones of bluish-gray color. 

 The zone, however, is clearly above the fine black shales of the 

 Marcellus, which contain numerous specimens of Liorhynchus 

 limitare (Vanuxem). 



On Mr. Robinson's farm is a small stream to the southwest of 

 Plum Run, on which are bluish shales and sandstones, some of the 

 latter being very hard and slightly calcareous. It is probable that 

 this sandstone zone corresponds with the lower one of the Hamilton 

 member of the Romney formation on the Williams Road, Mary- 

 land. Specimens of Spirifer mucronatus (Conrad) and Amhocoelia 

 umhonata (Conrad) occur sparingly. On the small hill to the south 

 of the run are yellowish to greenish, very argillaceous shales, con- 

 taining some fossils. Chonetes is abundant in certain thin layers 

 while other species, occurring more sparingly, are Spirifer mucro- 



