500 STEVENSON— THE FORMATION OF COAL BEDS, [^'ov. i, 



McKean county on the New York border. The area in Penn- 

 sylvania was not less than 3,000 square miles, while that of the 

 jNIercer was little more than 500. At the same time, one must 

 keep in mind that the Vanport was not continuous throughout its 

 area; that on the borders it extends in long diverging prongs, 

 terminating in chert or calcareous sandstone. The \"anport was 

 formed at the close of a somewhat rapid submergence, during which 

 many stream valleys were filled with sandstone. Apparently the 

 peculiar mode of occurrence, the variations in structure and com- 

 position along the borders were due to the topography ; while the 

 conditions in northern Ohio suggest that in that region the water 

 of the estuary was very shallow. In Pennsylvania and in a great 

 part of the Ohio area, this limestone has a rich marine fauna.^^ 



The roof shale of the Middle Kittanning coal bed, midway in 

 the Allegheny, contains Lingula and Discina as far north as Wayne 

 and Stark counties of Ohio. Aside from this, there appears to have 

 been no serious invasion during the Allegheny after the A^anport. 

 There are, it is true, several limestones, but there is no reason to 

 suppose that, excepting the newest of them, they are in any part of 

 marine origin. The Upper Freeport, almost the last Allegheny bed, 

 is the First Fossiliferous limestone of Kentucky, where it has a 

 marine fauna, but, north from the Ohio River, it resembles the 

 others in that the only fossils are minute forms, allied to those 

 usually regarded as freshwater types. 



The Ufifington shale of L C. White, the roof of the Upper Free- 

 port coal bed, often yields abundance of plant remains, but at some 

 widely separated localities on the eastern side, in ]\Ionongalia and 

 Upshur counties of West Virginia, as well as in Wirt county of the 

 same state, far within the Central area, it has a marine fauna ac- 

 companied by fragmentary remains of plants. Whether or not the 

 fauna exists elsewhere in the Central area is unknown, as the 

 horizon is below the surface and the well records are of no service. 

 The distribution of this deposit is without explanation in the present 



" The observations liy I. C. White, W. G. Piatt, Chance. Newberry, 

 Ortort, Hodge and E. B. Andrews are recorded in " Carboniferous," etc., as 

 above, Vol. 17, 1906, pp. 98-103, 113, 109-113, 116-121, 128. 



