420 CHARLES S. PROSSER 



the fourth one is the broad band covering the lower part of the 

 eastern face of Alleghany Front and extending from the Penn- 

 sylvania line southwesterly to the Potomac River above Keyser, 

 W, Va. The lower part of the formation composed of thin, 

 black, argillaceous shales in which a few species, such as Buchiola 

 speciosa, Liinulicardium fragile, and Sty Ho Una fisstirella are com-, 

 mon, immediately succeeds beds containing characteristic Ham- 

 ilton fossils, and is well shown on Flintstone Creek, a few rods 

 above its mouth, opposite the old Flintstone tannery ; by the 

 side of the National Road three miles northeast of Cumberland 

 to the west of Evitt's Creek at Folks Mill, and on the Williams 

 road east of Cumberland. This subformation corresponds in 

 lithologic character and stratigraphic position to the Genesee 

 shale of New York and No. VIII^" of Pennsylvania. 



Following this are olive to bluish fine argillaceous shales 

 alternating with thin bedded sandstones. A few fossils occur 

 in the more bluish layers. This division of the Jennings corre- 

 sponds to the Portage formation of New York, or that facies 

 named the Naples beds by Dr. Clarke, and No. VIII/ of Penn- 

 sylvania. Dr. J. M. Clarke, who has described the Jennings 

 fauna for the Maryland Geological Survey, writes me that the 

 fauna of these two lower divisions of the Jennings formation "is 

 very distinctly that of the Naples subprovince ; " and he states 

 that the lower division is considered " as an integral part of the 

 Naples beds, bearing the Naples fauna." ^ 



Succeeding the Portage are greenish arenaceous shales 

 weathering to a buff color alternating with thin micaceous sand- 

 stones. Occasional layers are fossiliferous and the character- 

 istic Chemung species, Spirifer disjutictus, is not uncommon. The 

 lithological appearance of this part of the formation is quite 

 similar to that of a considerable part of the Chemung in south- 

 western New York. Higher the sandstones predominate, and 

 these vary in color from yellowish-gray through brownish-gray 

 to dark red, and vary in texture from sandstone and grits to a 

 white pebble conglomerate. Some of these sandstones are quite 



'Letter of June 19, 1901. 



