peale.] GEOLOGY ANTHRACITE CREEK COAL CREEK. 99 



for which he says the Indian name is Bah. Bah, or more properly Pah, 

 is the Ute word for water. Gunnison's map* gives it the name of North 

 Fork, which is the name in common use, and therefore we retain it. 

 The group of mountains about the sources of Anthracite Creek were 

 named by Lieutenant Buffnert the Philosophers' Monuments, and the 

 names of Owen, Spencer, Huxley, Mill, and Carpenter given to some of 

 the most prominent peaks. His Mount Bichard Owen probably corre- 

 sponds to our station No. 32. 



Geologically this whole region about the sources of Slate Biver, Bock 

 Creek, Ohio Creek, and the North Fork of the Guunisan is exceedingly 

 complicated. Tne Cretaceous formations which prevail here seem to 

 have been disturbed by igneous eruptions, and they are found at 

 places in great confusion, dipping in almost every direction and pene- 

 trated by numerous dikes. Cretaceous shales, mingled with trachyte, 

 are found on the summits of some of the highest peaks. It is therefore 

 difficult to get at the exact thickness of the strata or to tell the exact 

 horizon to which beds ought to be referred, as they are oroken apart 

 and very much metamorphosed. The country is very rough and rugged, 

 the peaks being high and often very difficult of ascent. It will require 

 some time to work this region up iu detail, and close and careful study 

 will be required to reduce it to a system. Station No. 32 is composed 

 principally of metamorphosed Cretaceous shales, intersected by dikes. 

 A large dike crosses Anthracite Creek, having a course from station 32, 

 South 22° West. Southeast of the station is a ridge of Cretaceous strata 

 which heads a branch of Anthracite Creek on one side close by one of the 

 sources of Ohio Creek, and on the other overlooks the sources of several 

 branches of Slate Biver. All these streams rise in amphitheaters, the 

 edges of the strata forming steps, rising one above the other. The 

 streams rise in beautiful emerald lakelets. The course of this branch 

 of Anthracite Creek at first is nearly due south. It then curves around 

 station 32 and flows northwest for ten miles, when it turns abruptly 

 around a sugar-loaf-shaped mountain and flows west, through a canon 

 cut principally in gray sandstone. In this canon it is joine*d by the west- 

 ern fork, Coal Creek, when it again changes its course and flows north for 

 three miles to the North Fork. 



The isolated peak around which Anthracite Creek flows was named 

 Marcellina by a party of prospectors that we met on North Fork. It is 

 composed of a light-gray porphyritic trachyte. It answers the description 

 of Mount Huxley in Lieutenant Buffner's report.f but on the accompany- 

 ing map Mount Huxley is located on the opposite side of the creek. 



The western branch of Anthracite Creek, Coal Creek, rises generally 

 on the rim of a basin of Cretaceous shales and sandstones (see map C), 

 which is bordered by hills of trachyte and breccia, the latter being on 

 the eastern side, and an extension from station 31. For some distance 

 above its junction with the eastern fork it flows through a canon, of 

 which the walls are about a thousand feet in vertical height. The sand- 

 stones and shales composing them are perhaps slightly inclined toward 

 the northeast, not more than 3° to 5°. There are outcrops of coal at 

 various points along the western fork, but the coal is of poorer quality 

 than that on the eastern fork. 



The other stream, which unites with Anthracite Creek to form the 

 main North Fork, rises opposite Bock Creek and the branches of the 



* Pacific Railroad Report, vol. xi. 



t Report of a Reconnaissance, &c, by Lieut. E. H. Rutfner, Corps of Engineers, 

 page 40. 

 tibia., Page 41. 



