282 GEOLOGICAL EXCURSION TO THE ROCKY MOUNTAINS. 



this from the usual breadth of the valleys, and dip of the hard rocks 

 above (Portage) and below (Oriskany), if no rolls are present* Ike 

 entire thickness of the Hamilton rocks, including Man-dins, Hamilton 

 proper, and Genesee, in the region of Cumberland and Keyser, can not 

 be less than 3,000 feet, 



Chemung Scries, ( VIII). Total thickness 5,000 feet. 



The Portage beds consist of olive gray shales and flaggy layers, spar- 

 ingly fossiliferous; thickness probably about 1,000 feet. 



The Ohemung beds consist of olive shales, flaggy sandstones, and one 

 massive conglomerate (Allegrippns) near the topj thickness about 2,500 



feet. 



The Cats-kill beds are a series of reddish shales, green and red sand- 

 stones, with conglomerate layers in lower half; thickness L,500 feet 



The Ohemung* rocks have a line development along the line of the 

 Baltimore and Ohio Railroad, easl as well as west from Cumberland. 



West from Cumberland the lirst exposure of these beds is about two 

 miles west from Keyser, where the Ohemung proper is fairly well 

 exposed, dipping down under the great trough of the Cumberland coal 

 basin. Then follow the red shales and sandstones of the Catskill, but 

 the latter reappear along the Savage River after the railroad has 

 crossed the Potomac coal basin and begins the, long climb up the 

 "17-mile" grade to the summit of the Alleghany .Mountains at Alta- 

 mont. The Catskill beds are covered np by tin' Pocono (Lower Car- 

 boniferous) sandstones in the summit cut at Altamont, but reappear 

 just west from it and extend along the Baltimore and Ohio to Deer Park 

 and a mile beyond, where the Negro Mountain anticlinal, which crosses 

 the Baltimore and Ohio at Mountain Lake Park, :'» miles west of Deer 

 Park, brings up the soft shales and conglomerates of the Chemung 

 proper. Then these beds turn over and descend under the Youghio- 

 ghenv River coal basin, to be brought to the surface again on the crest 

 of another great arch at Terra Alta, and are constantly in sight from 

 there down the western slope of the Alleghanies to Cheat River, at 

 Rowlesburg, and two miles beyond, where the red Catskill beds pass 

 under water level, to be seen no more to the west. 



Pocono sandstone (X). Loieer Carboniferous. 



V Fret. 



Thickness near Piedmont about 1,000 



Thickness on Cheat Hiver, near Rowlesburg 600 



Thickness at Mannington 4(W 



A series of hard, gray, current-bedded sandstones, usually of rather 

 fine grain, but occasionally containing flat pebble conglomerates, inter- 



*The term Chemung as hero used includes the three epochs of Portage, Chemung, 

 ami Catskill, as proposed by Dr. Jno. J. Stevenson in his viee-presidential address 

 before Section K.ai the Washington meeting of the "A. A. A. 8.." August 1891. 



