white] CUMBERLAND TO THE OHIO RIVER. 283 



stratified with sandy shales, comes next above the Oatskill red beds. 

 The series is first seen on the Baltimore and Ohio between Keyser and 

 Piedmont, where it has a thickness of 1,000 feet, and makes the east 

 front ridge of the Alleghany Mountain, on the south side of the 

 Potomac, and Dan's .Mountain, on the north side, but soon dips rapidly 

 down under the Cumberland coal basin. 



These beds come up again a few miles west from Piedmont and are 

 seen making the steep upper escarpment of Big and Little Savage 

 mountains, westward to the top of the u 17-mile grade" at the summit 

 of Hack Bone Mountain, near Altamont, where the highest cut, at 2,620 

 feet elevation, is through these sandstones. 



It is seen again at Oakland, making a hue cliff near the Baltimore and 

 Ohio hotel, and dipping down under the Voughiogheny coal basin, to 

 come up and pass into the air just east from Terra Alta, and then, eom- 

 ing down again, makes the summit of Briery Mountain, the most 

 western ridge of the Alleghany range, and, passing under the Baltimore 

 and Ohio Railroad for the last time just west of Rowlesburg. assists in 

 shaping the grand scenery along the Cheat River gorge between Buck- 

 horn Wall and Rowlesburg. 



The upper portion of this sandstone series is the great oil and gas 

 depository of West Virginia; at Mannington, on the Baltimore and Ohio 

 Railroad, where this stratum lies 1,800 feet below the surface, a large 

 oil field, extending northeast to the Pennsylvania line and southwest 

 for an unknown distance, lias been developed in these beds. 15 



Mountain limestone <at<l Maueh Chunk red shale {XI). — This sub- 

 division of the Lower Carboniferous, like the Pocono beds below, is 

 more closely allied to the Oatskill series, both in its lithological aspects 

 and in its fossils, than to the Coal Measure series above, which always 

 rests unconformably upon it. 



The bottom member of the series, the Mountain limestone, where 

 crossed by the Baltimore and Ohio, just east of Piedmont, is .'! 10 feet 

 thick, (ptite fossil iferous. and consists of gray limestone interstratilied 

 With marly gray shales, and some red beds, the lowest 30 feet being a 

 SiliciouS limestone merging gradually into the Pocono sandstone below. 

 On Cheat River, west from Rowlesburg, where the Baltimore and Ohio 

 grade cuts through tin's series it is L'T.'! feet thick, of which the silieious 

 member at its base measures 105 feet. West from Rowlesburg the 

 Mountain limestone is seen no more, but at Mannington the drill passes 

 through it at 1,000 feet below the surface, where it is 00 feet thick, while 

 at Bellaire it is still 30 to 60 feet thick, as determined by drill holes. 

 As is well known, this Mountain limestone thins away entirely, to the 

 northeast along the Alle-hanies. and is not found anywhere in north- 

 eastern Pennsylvania, buf southwest from the Baltimore and Ohio Rail- 



