PEALE.] GEOLOGY UPPER CRETACEOUS COAL. 139 



bed, aud followed it up until the bed was reached, near the head of the 

 stream. The original discovery was made, I believe, by prospectors. 

 The existence of coal of a good quality in the Elk Mountains has been 

 known for several years. In the report for 1873 (page 259) I referred to it. 

 The coal was exposed on both sides of the creek, the dip being nearly 

 in the direction of the course of the stream, inclining about 25°. The 

 beds are tipped up against the Trachytic range that forms part of the 

 divide between Anthracite Creek and Ohio Creek. The coal is in a 

 bed from 4 to 5 feet thick. The following is the section from the coal 

 down : 



1. Coal, 4 to 5 feet thick. 



2. Black slates and shales, with interlaminated dark sandstones, 

 reaching to the creek-bed, about 150 to 200 feet thickness in all. 



Above the coal is "a bed of sandstone, brownish near the coal, becom- 

 ing lighter colored as we ascend. The sandstone is succeeded by light- 

 gray sandstones and interlaminated dark shales. About 100 feet above 

 the coal is a layer of porphyritic trachyte, which inclines with the sedi- 

 mentary beds. It is probably an intrusion, as it resembles closely the 

 trachyte from the various eruptive masses in the surrounding country. 

 It contains iron, which gives it a rusty appearance on weathered sur- 

 faces. The coal will be referred to in a subsequent part of the report, 

 ■when analyses will be given. Coal is also found on Coal Creek, and at 

 the head of Slate Eiver, and on Rock Creek. It is all probably of the 

 same age. 



In sandstone shales, near Mount Marcellina, I found a specimen of 

 Ferrea sternhergii. Although I searched carefully, this was the only 

 fossil I could find that was distinct enough for identification. This and 

 the Aralia I found in layer 12 of section No. 17, on Grand River, are 

 the only fossils found in the series and do not warrant any definite con- 

 clusion as to their age. 



The beds in section ISo. 17 have probably their equivalents in section 

 iSfo. 18, but in the latter they have been so changed that we cannot say 

 so with any certainty. 



I have already referred to the possibility of a portion of this group 

 being a part of the Fox Hills beds (No. 5). A part, also, may belong to 

 the Lignitic group, (so named east of the mountains.) 



Since writing the above I learn from Mr. Marvine that he found a 

 coal-bearing series of shales above typical specimens of No. 4 Cretace- 

 ous, aud that above the coal he obtained fossils referred to No. 5 by 

 Prof. F. B. Meek. 



Dr. Endlich also found coal above No. 4 in the Cretaceous. 



It is therefore probable that the beds I have, for convenience, de- 

 scribed as Upper Cretaceous belong to No. 5. 



From the lowest to the highest beds exposed in my district I could 

 find no uuconformability. 



