Ashburiior.] '^40 fFeb. 16, 



On iiccount of the great variability of tiic liinestonc beds, the above can 

 hardly be proposed as a distinct division characteristic of the series. 



To bring the section into accord -with observations made at other locali- 

 ties, in the bituminous region of the State, it might be well for conve- 

 nience of comparison to divide tlie series into an upper and a lower lime- 

 stone member, separated by a middle mass of shale, as indicated. 



Where the limestone was studied in Smith's and Plank Cabin Valleys, 

 the upper member is composed of more impure and argillaceous beds than 

 the lower, and the only parts of the series which have as yet proved of any 

 very groat economical value, are the variegated red and gray limestone 

 No. 224, and the more massive gray stratum No. 223, the latter by analysis 

 containing 92.:52 per cent, of carbonate of lime. 



In two localities fossil remains were found in the upper member. In 

 Well's Valley to the south of Broad Top Mountain, near Wishard's old 

 saw mill, a bivalve shell and a coral were found (Roger's Vol. I page 530), 

 and at the quarry near Todd P. O., in Plank Cabin Valley, the following 

 genera and species were collected from stratum No. 228, Orammyda, 

 Strophodonta, RhyncTionella and Terabratula Rainingeri. In No. 226 a 

 Centronella was disclo-sed. A close study of the outcrop in Plank Cabin 

 Valley would no doubt result in the finding of other species. 



Prof. Rogers (Vol. I, page 472) reports that this limestone series can be 

 traced from the Conemaugh River along Chestnut and Laurel Ridges to 

 the Southern boundary of the State. 



"It occurs as a more or less silieious limestone, containing well rounded 

 grains of sand of a light blue color, sometimes having a yellowish tint. 

 The upper part is remarkably full of fossils as is also the central mass of 

 shale" 



The series seems to feather to the north on the Alleghany Mountain near 

 the sources of the Conemaugh, gradually augmenting through the southern 

 part of the State and Maryland until in Greenbrier Mountain. Pocahontas 

 County, W. Va., it attains a thickness of 822 feet, known as the Lewis- 

 burg limestone. It ranges in force still further south through Eastern 

 TennessL'C and Northern Alabama to the end of the Appalachian coal belt 

 in the latter State. In the west the mountain limestone is known as the 

 St. Louis and Chester. groups. 



Prof. Fontaine (Silliman's Journal, Jan. 1877) proposes the mountain 

 limestone for a base to the Umbral (Maueh Chunk) No. XI ; first, on ac- 

 count of the physical character and composition of the red shales between 

 the Vespertine (X) and the limestone ; second, on account of the subordi- 

 nate position which the limestone would otherwise occupy in the compara- 

 tively restricted Umbral Series. 



There are several objections to this classification ; 



Ist. Although the red shale which occurs under the Mountain Limestone 

 undergoes a rapid and i)rogre3sive attenuation to tlie west and south-west, 

 the limestone itself is not found in the anthracite region where the ^lauch 

 Chunk series has its greatest development, and is a red shale tbrmation 



