Maryland Geological Survey 353 



hills parallel to and about half a mile from the outer and upper contact of 

 the formation." ' 



Succeeding the conglomerate in Jennings Run are 550 feet of rocks 

 that have been put in the Jennings formation in which Chemung fossils 

 occur. These rocks consist largely of coarse grained, micaceous, greenish- 

 gray and brownish-red sandstones alternating with shales. In Garrett 

 County there are zones above the flat pebbled conglomerate in which 

 abundant specimens of Chemung fossils occur, among which the charac- 

 teristic species Spirifer disjunctus Sowerby is common. This pai't of the 

 formation contains the most fossils and is one of the best collecting 

 grounds for Chemung fossils in Maryland. The soil derived from the 

 Jennings formation is yellowish in color. 



The thickness of the Jennings fonnation of Maryland, varies, according 

 to the measurements of Swartz and Ohern, from 3400 to 4750 feet. It 

 represents the Genesee shale and Portage and Chemung stages of Xew 

 York and Xo. YIII, e, f, and g of Pennsylvania. 



DISTRIBUTION OF THE JENNINGS FORMATION 



The most eastern Jennings rocks in ^laryland are found just west of 

 the eastern belt of the Licking Creek area of the Romney fonnation and 

 extend westward for 4 miles to Pigskin Ridge. Near the middle of this 

 area on the Potomac River is Millstone which furnishes an appropriate 

 name for this area of the Jennings. To the west of Timber Ridge, includ- 

 ing the valley of the Great Tonoloway Creek, and extending nearly to 

 Hancock is a belt of the Jennings formation about 11/4 miles in breadth. 



In the western part of Washington County to the west of the Tonolo- 

 way area of the Romney formation a belt of the Jennings formation 

 varying from three-fourths to nearly 1 mile in breadth crosses the state 

 in a parallel direction to that of the Romney ai"ea just mentioned. West 

 of Sideling Hill is another belt of the Jennings formation, about li/4 miles 

 wide on the jNiaiyland-Pennsylvania state line, in which part of the 

 valley of Sideling Hill Creek has been excavated, and the greater part of 

 this area lies to the west of this creek in the eastern part of Allegany 



' Md. Geol. Surv., Garrett Co.. p. 87. 

 23 



