REPORT OF A GEOLOGICAL RECONNOLSSANCE ALONG THE 



UNION PACIFIC RAILROAD. 



The followiug pages contain an account of a portion of the geological 

 reconnaissance made by Mr. Meek and myself in the coal-bearing forma- 

 tions along the line of the Union Pacific Eailroad in the summer oi 

 1872, in couuectiou with the United States geological survey of the 

 Territories, Dr. F. V. Hayden in charge. The work comprised the col- 

 lection of fossils from these beds, and taking sections and such other 

 notes as would serve for the correct establishment of the various hori- 

 zons in which the collections were made, with a view of obtaining fuller 

 data for forming a correct idea of the formations and for the determina- 

 tion of their age. I have, therefore, given a consecutive account of all 

 the localities visited by us, which are not elsewhere reported on by Mr. 

 Meek, with our examinations at each; not, however, entering into ques- 

 tions of economic geology, or, of general structure, except in so far as it 

 appeared necessary for the elucidation of the points in view. In 

 In making this report, in addition to those taken by myself, I have been 

 kindly allowed the use of the field-notes of Mr. Meek. 



Caebon. — The first localitj^ where we made any examinations was 

 Carbon Station, the easternmost point where the coal of this region has 

 been opened and extensively worked. Here we stopped a day and ex- 

 amined carefully for fossils in the natural and artificial exposures near 

 the station. The structure here seemed a little complex, the beds con- 

 siderably faulted and upturned, but we obtained an a])proximate section 

 sufljciently accurate as to the relative location of the diiferent beds 

 from which we obtained specimens. The coal appears to lie in a local 

 synclinal, the dip of the rocks immediately west of the station being 

 from 20° to 30° in a general direction from east-southeast to southeast, 

 while on the opposite side of the little basin or trough it was about 

 15° to 20°, the direction varying from southwest to west or north ol 

 west. From the difi'erent exposures, and from the testimony of the 

 miners as to the beds passed through in sinking shafts, we made the 

 following approximate section : 



Section of the strata at Carbon, Wyoming. 



Feet. In. 



1. Argillaceous shale 8 



2. Coal 6 



3. Sandstone and sandy shale 59 



4. Argillaceous shale 2 to 5 



5. Coal 9 



G. Light-colored sandy and argillaceous shales, with im- 

 pressions of leaves 18 to 20 



7. Coal . . 3 to o 



8. Light-colored sandy shale 9 



1^. Coal 4 or 5 



10. Light sandy beds, sandstone, and, perhaps, some coal, 



(estimated) 40 to 50 



