226 CLARK AND MARTIN — THE COAL MEASURES OF MARYLAND 



represents the Elklick coal of Pennsylvania and West Virginia, is found 

 at about 35 feet above the Ames limestone. 



Morgantown sandstone (39). — Immediately above the Elklick coal or its 

 horizon, if the coal is absent, is a very massive and constant sandstone, 

 frequently conglomeritic in part, which corresponds exactly in its strati- 

 graphic relations with the Morgantown sandstone, so called from its 

 typical development at Morgantown, West Virginia. 



Clarksburg limestone (40). — A short distance above the top of the Mor- 

 gantown sandstone is a limestone from 3 to 9 feet in thickness. This 

 limestone has a rather characteristic appearance and contains abundant 

 fossil fish and Ostracoda. Marine fossils are entirely absent. In its 

 stratigraphic position, its lithologic characteristics, and the general nature 

 of its fauna this limestone corresponds to the Clarksburg limestone, so 

 called from its occurrence at Clarksburg, West Virginia. 



Franklin or Little Clarksburg coal (41). — A seam of coal which is iden- 

 tical with the Little Clarksburg coal of Dr I. C. White is found imme- 

 diately above the Clarksburg limestone. In the Georges Creek basin this 

 coal is popularly called the " Dirty-nine-foot," and in the Report on 

 the Geology of Allegany County it was named the Franklin coal from 

 its occurrence near the town of Franklin. 



Connellsville sandstone (42). — A short distance above the Franklin coal 

 is a very prominent sandstone of considerable thickness. It is very 

 strongly developed in the Georges Creek and Potomac basins, where it 

 has a very marked influence on the topography. This sandstone is 

 found in the stratigraphic position of the Connellsville sandstone of 

 southwestern Pennsylvania. 



Lower Pittsburg limestone (43). — Almost immediately above the Con- 

 nellsville sandstone is a thin limestone containing no fossils except 

 Ostracoda, as far as observed. It has all the characteristic features and 

 is evidently the Lower Pittsburg limestone. 



Little Pittsburg coal (44). — Immediately above the last-mentioned lime- 

 stone and from 50 to 90 feet below the top of the formation is a seam of 

 coal from 1 to 3 feet in thickness. This is the equivalent of the Little 

 Pittsburg coal of Pennsylvania. 



MONONGAHELA FORMATION 



Composition and relations. — The strata composing the Monongahela 

 formation in Maryland consist of a series of shales, sandstones, lime- 

 stones, and coal seams. The thickness varies from 240 to 260 feet. The 

 formation is entirely restricted in Maryland to the Georges Creek- 

 Potomac basin. The name " Monongahela series " was proposed by 



