412 The Upper Devonian Deposits of Maryland 



■which M'eatlier into tliin fragile ilakes witli parallel sides. The shale is 

 quite cailjoiiaceous and becomes chocolate brown upon prolonged weath- 

 ering. Many exposures of considerable thickness exhibit a system of 

 well-developed joints, which intersect nearly at right angles to the bed- 

 ding, a feature frequently seen in the Genesee formation of New York. 



This member is 90 to 100 feet thick west of Wills Mountain. It di- 

 minishes in tliicknoss and finally disappears eastward, the most easterly 

 exposure observed being on the flanks of the anticline forming Strafford 

 Eidge, east of Oldtown. 



Fauna. — The Genesee shales ahound in individuals of a few species. 

 The fossils are chiefly minute pelecypods associated with pteropods and 

 goniatites. The following species occur in this member according to the 

 identifications of Dr. J. M. Clarke : Bucliiola retrosh-iaia, Buchiola con- 

 versa, Buchiola livomae, Pterochcpfiia fragilis, Lunulicardium encrinitmn 

 StylioUna fissurella, PliareireJla tenehrosa, Tornoceras uniangulcire, Pro- 

 heloceras lutheri, Bactrites acictdini, Orihoceras filosum. 



Eomney-Genesee Boundary. — The boundary between the Genesee 

 and Eomney is well defined both lithologically and topographically. A 

 massive sandstone occurs either at, or a short distance below the top of 

 the Eomney, while the shale of the upper part of that formation breaks 

 into fragments of very irregular shape which weather to a yellowish or 

 greenish color, contrasting sharply with the smooth fissile brown, or 

 black platy fragments of the Genesee. The Genesee usually occupies a 

 valley developed between the upper sandstone of the Eomney and the 

 hard resistant olive-green shale of the Woodmont shale member. 



Woodmo-tit Shah' Member 



Character and Thickness. — The Woodmont shale member receives 

 its name from Woodmont Station, Washington County, % mile east of 

 which it is well exposed in the cut of the Western Maryland Eailroad. 

 This station is situated about % of a mile west of Tonoloway Eidge 

 which is opposite Great Cacapon, W^est Virginia. It is also finely exposed 

 at many places on the banks of Town Creek. It overlies the Genesee 

 shale member conformably or in the absence of the latter, the Eomney 



