350 The Upper Devonian Deposits of Maryland 



either project from or drop out of the matrix so that its appearance is 

 quite different from that of the lower, conspicuous conglomerate. 



In Bedford and. Fulton counties in Pennsylvania to the north of Alle- 

 gany County, Maryland, Professor Stevenson descrihed two conglomerate 

 layers in the Chemung separated by 950 feet of shales and sandstones 

 which he designated from their stratigraphic positions the lower and 

 upper conglomerates." ' The upper part of the Chemung is imperfectly 

 shown in both Bedford and Fulton counties; but Professor Stevenson in 

 his " generalized section " for the latter county has given 800 feet of 

 " shales with occasional beds of sandstone " as overlying the upper con- 

 glomerate before the top of the Chemung is reached." From their 

 stratigraphic position it is evident that the two conglomerates just 

 described in Maryland do not represent the lower and upper conglomer- 

 ates in Pennsylvania both of which contain flat pebbles as described by 

 Professor Stevenson. The upper one of Professor Stevenson, however, 

 occurs near the stratigraphic position of the lower one just described in 

 Maryland and there is some probability that these two are identical. This 

 opinion is somewhat strengthened by Professor Stevenson's statement 

 that in Bedford County the beds overlying the upper conglomerate are 

 quite fossiliferous containing Spirifer disjunctus Sowerby, Strepto- 

 rhynchus chemungense (Conrad), Oriliis closely allied to 0. tioga Hall, 

 and " great numbers of characteristic Chemung Lamellibranchs." ' Dr. 

 I. C. White correlated the upper conglomerate of Stevenson with his 

 Lackawaxen conglomerate found on the bluff of the Delaware River near 

 the town of that name in northeastern Pennsylvania.* Although later, 

 in describing the formations west of Cumberland, he stated that " The 

 Chcmnng beds consist of olive shales, flaggy sandstones, and one massive 

 conglomerate (Allegrippus) [the name which he gave to Stevenson's 

 lower conglomerate °] near the top; thickness about 2500 feet."" Dr. 

 Martin also wrote that the flat pebble conglomerate of Garrett County 



' 2d Geol. Surv. Pa., T-, 1882, p. 76. 

 -Ibid., p. 75. 

 ^ lUd., p. 78. 



*IMd., T^ 1885, p. 90, f. n. p. 91, and section on p. 96. 

 ''Ibid., pp. 99, 101, 103. 



"Congres Geolg. Internat., Compte Rendu de la 5me Ses., Washington, 1901 

 (1903), p. 282. 



