Maryland Geological Survey 359 



Exposures in Allegany County 



Exposure 'West of Sideling Creek. — x\fter crossing the crest of Sideling 

 Hill there are outcrops of Pocono sandstone on the western side in which, 

 not far below the summit, is a small opening for coal. Lower are numer- 

 ous outcrops of the red shales and sandstones of the Catskill formation 

 and a thick band of red argillaceous shale is shown just east of the Side- 

 ling Creek bridge. One mile west of the creek is a band of somewhat 

 calcareous sandstone in which are fossils mainly Spirifer mesacostalis 

 Hall, Spirifer mesastrialis Hall, and Spirifer (Esjnncius Sowerby asso- 

 ciated with Sphenotvs contractus Hall and a few other pelecypods. 

 This rock weathers to a rusty-brown rottenstone due to the leach- 

 ing of the calcareous material. Immediately below the zone of fossils 

 is a red sandstone stratum beneath which are red argillaceous shales. 

 The dip at this locality is 12° N., 70° W. The rocks of this zone 

 belong in the Upper Chemung and it is to be noted that these fossils 

 occur above red rock. As has already been indicated the red rocks in 

 western Maryland occur at ditferent horizons so that it would be im- 

 possible to separate formations by the first appearance of red rocks. A 

 better means of classification is that made by the last appearance of fossils 

 considering the rocks below such a horizon as of Chemung age. In this 

 case in the vipper part of the Chemung or Jennings formation there will 

 be found bands of red rock which in the western part of the state are 

 confined to the Chemung member of the Jennings formation but in 

 Washington County appears as early as the Parkhead member. 



From collections made in the vicinity of Sideling Hill Creek Dr. J. M. 

 Clarke has identified the following species: Fawosites sp., Helioplujlluni 

 scrutarium Clarke, Spirorhis gyrus Clarke, Ambocoelia umhonata (Con- 

 rad), Productella lachrymosa (Conrad), var., Spirifer mesastrialis Hall, 

 Sphenotus contractus Hall, Bellerophon sp. 



Exposure Northwest of Little Orleans. — The rocks in the vicinity of 

 Little Orleans belong in the Jennings and Catskill fomiations. The road 

 to the northwest of Little Orleans runs along Fifteen Mile Creek for some 

 distance and then climbs a steep hill. The rocks of the lower Jennings 

 formation are exposed in Fifteen Mile Creek, in the vicinity of Little 



