Maryland Geological Survey 349 



succeeding part of the Jeiuiings formation he correlated with the Che- 

 mung of New Yorlv. 



In the Jennings Eun section tliere is a 40 foot zone of sandstone and 

 conglomerate shown in the highway cut about 550 feet below the top of 

 the formation. In Garrett County the conglomerates are quite con- 

 spicuously represented by loose blocks; but are not often found in place. 

 One, containing quite large flat white quartz pebbles, is found frequently 

 to the northeast of Oakland and in the vicinity of Mountain Lake Park. 



This conglomerate is light gray in color, slightly fossiliferous, con- 

 tains numerous milky quartz pebbles, part of which at least are flat and 

 lenticular in shape, but none of jasper were seen by the writer, while the 

 jointing surfaces of the blocks cut directly across the pebbles making a 

 smooth surface. Apparently the rock always breaks straight across the 

 pebbles in a direction at right angles to their bedding, and the cementing 

 material is dark, gi'itty, and somewhat ferruginous. Regarding the 

 presence of jasper pebbles Dr. Martin has written as follows : " I have 

 not noticed jasper pebbles in the Chemung near Corriganville [Jen- 

 nings Run section], I have seen a few in the vicinity of Mountain Lake 

 Park and Oakland and also to the south of Oakland. I do not remember 

 seeing them elsewhere.'' ' It is clearly shown at several localities to the 

 northeast of Oakland that this conglomeiate is succeeded by a considerable 

 thickness of rocks containing abundant specimens of Spirifer disjunctus 

 Sowerby, Ati-ypa liystiix Hall, Douvillina caijida Hall, and other Che- 

 mung species so that there can be no doubt that the stratigraphical posi- 

 tion of this conglomerate is considerably below the top of the Chemung. 

 In this region a higher conglomerate occurs about 50 feet below the base of 

 heavy reds which are considered as forming the base of the Catskill forma- 

 tion.^ This stratum, 6 inches more or less in thickness, occurs in the 

 midst of yellowish-green shales a.nd contains numerous quartz pebbles 

 which are not so lenticular in shape as those in the lower conglomerate. 

 On Pea Ridge, southeast of Avilton, in the northern part of the county a 

 similar conglomerate occurs, containing small, mostly rounded quartz 

 pebbles which do not break with a smooth fracture on the joint planes but 



'Letter of January 12, 1901. 



■ See an alternative interpretation by C. K. Swartz in this volume. 



