202 ENVIRONMENT OF VERTEBRATE LIFE, ETC. 



conspicuous, very coarse, and at times for miles almost continuous from bottom 

 to top of the formation, composing in part Mr. Campbell's Charleston sandstone. 

 Farther north, in the Potomac area, the sandstones are differentiated, broken by 

 beds of shale; yet even there the Butler and Clarion are massive, the former at 

 times pebbly. The sandstones are irregular in Broad Top and the pebbles are 

 few. Within western Pennsylvania the Butler and Freeport sandstones appear 

 to be most nearly persistent, and each of them occasionally shows some pebbles; 

 but they vary greatly in thickness and each of them is often replaced by shale 

 in tracts containing hundreds of square miles. Well records in the deep portion 

 of Ohio and West Virginia usually show more or less sandstone in one or more 

 of the intervals, but many show so little aside from shale that the sandstone must 

 be due merely to local sorting of material. Pebbles are repotted only from Wirt 

 County of West Virginia. The great sandstones of the eastern outcrop in West 

 Virginia break within a few miles toward the northwest; thin shales appear, 

 which soon increase in thickness, and the sandstones become unimportant. 

 Along the western outcrop in Ohio, sandstone is most nearly persistent in the 

 Butler and Freeport intervals. Ordinarily fine in grain, the latter shows pebbly 

 streaks in Stark, Carroll, Harrison, Wayne, Tuscarawas, and Muskingum Coun- 

 ties that is, along the northwestern side; yet in all of these counties not a few 

 sections show only shale. The Clarion (Hecla) sandstone becomes very con- 

 spicuous in southern Ohio and is equally so farther south and southwest in 

 Kentucky. It is noteworthy that a conglomerate is present in parts of Kentucky, 

 near the horizon of the Vanport limestone, and that at one locality the ore 

 associated with that limestone is so crowded with quartz pebbles as to be worth- 

 less. 



"The character and distribution of the sandstones show sufficiently a great 

 advance of the shore-line or a considerable elevation of land at the southwest. 

 The former condition seems the more probable, and the Allegheny deposits can 

 have extended hardly so far in that direction as did those of the Beaver. The 

 shore-line at the east-southeast must have been at only a short distance from the 

 present outcrop, as the strip of sandstone is very narrow. Coarse material 

 could be pushed only a little way in the shallow water of that time. There is 

 much to suggest a similar advance of the shore at the northwest, not only in the 

 unexpected coarseness of the sandstone, but also in distribution of the limestones. 

 The presence and great predominance of sandstone in Kentucky, on the southern 

 and southwestern borders, is equally suggestive of land encroachment in that 

 direction." 



The Putnam Hill limestone of Ohio is said by Stevenson to be very 

 fossiliferous and to mark an invasion of the sea from the west ; similarly the 

 Black Flint on the Kanawha River, at the same horizon, is said to mark an 

 invasion from the Atlantic in the form of a branching bay. 



"The Vanport (ferriferous) limestone marks a still greater inroad of the 

 interior, or Mississippian, sea, reaching in northwest Pennsylvania almost to the 

 New York line. * * * On the Kanawha, in West Virginia, Professor W. B. Rogers 

 found a bed crowded with marine forms at 140 feet above the black flint, too 

 high for the Vanport horizon, but of interest as proving access to the Atlantic 

 at more than one time during the Allegheny. * * * No later important inroad 

 of the sea occurred. The fossiliferous shale over lying the middle Kittanning is 

 found only as far north as central Ohio, while the lower and upper Freeport lime- 



