348 The Upper Devonian Deposits of Maryland 



though there are occasional strata 2 feet in tliickness, occur throughout 

 this part of the formation ; but as a rule are not thick enough to be of any 

 economic importance. In Washington County brownish-red shales occur 

 in the upper part of this division ; but in Allegany County reddish rocks 

 make their first appearance in the succeeding member. Fossils are not 

 common near its base although specimens of Buchiola retrostria^a v. Buch, 

 Pterochaenia fragUis (Hall), Tornoceras uniagulare (Conrad), Bactrites 

 aciculus (Hall) and some other species occur. A profuse fauna has been 

 observed in the higher strata of this member by Dr. Swartz who correlates 

 them with the Ithaca beds of New York. Its thickness is estimated at 

 1200 to 1600 feet. This division of the Jennings formation has been 

 named the Woodmont member by Swartz and is regarded as representing 

 the Sherburne and Ithaca stages of New York. It is fairly well shown on 

 the bank of Town Creek and the lower slope of Polish Mountain on both 

 the National and Williams Eoads and in the upper part of the section near 

 Woodmont west of Tonoloway Station. 



The succeeding division, named the Parkhead member by Swartz and 

 Stose, consists of shale and interbedded sandstones and conglomerates. It 

 was showTi to contain an abundant fauna of Hamilton affinities by Dr. 

 Swartz who discusses it more fully elsewhere in this volume. Its thickness 

 is 400 to 600 feet. 



The upper part of the Jennings formation consists of argillaceous and 

 arenaceous shales alternating with beds of sandstone which are very 

 often micaceous, while several layers of conglomerate occur in this mem- 

 ber. These shales and sandstones are iisually greenish or greenish-gray 

 in color and weather to a yellowish-green ; but there are not infrequent 

 zones of brownish-red shales and sandstones. In certain layers fossils are 

 common and the characteristic species Spinfer disjunctiis Sowerby of the 

 Chemung stage occurs frequently and this together with the presence of 

 other Chemung species, lithologic similarity and stratigraphic position 

 indicates the correctness of the correlation of this division with the 

 Chemung stage of New York. 



The writer correlated the beds between the top of the Genesee shale, or 

 where this shale is absent the top of the Romney, and the lowest ones con- 

 taining Spirifer disjunctiis Sowerby with the Portage of New YorJc. The 



