Hayden.] gQ^ [January. 



thing that I have so far seen points out that the coal is either creta- 

 ceous or tertiary, but I believe it to be tertiary, or of the same age as 

 the coal near Cologne, on the Rhine; but I am perplexed at the in- 

 version of the dip of the coal, sandstone, and the iron ore which 

 here incline toward the mountain instead of away from it, and 

 nothing else that I have observed can compare with these tilted up 

 beds. I have not time now to follow up this subject, nor to give you 

 all the data that I have gathered so far; I shall report to you in full 

 in regard to the points you mention, but will give you as soon as 

 time permits a full report, with elevations, profiles, &c.; also, some 

 specimens to prove the relative age of the strata shown in my 

 sketch." 



Mr. Berthoud has forwarded several newspapers published in 

 Colorado Territory, with advertisements of coal for sale at so much 

 per ton at the mines, or so much delivered. It is somewhat strange 

 that since so many practical geologists have travelled over this coun- 

 try for the purpose of examining mines, no definite statement, sub- 

 stantiated by the proper proofs, has ever been placed on record with 

 regard to the age of these coal beds. It only shows that while a man 

 may be a good mineralogist and theoretical geologist, he fails in at- 

 tempting to work out the structure of a country over large ai-eas. 



By permission of the Commissioner of the United States Land 

 Office, at Washington, Dr. Hayden had an opportunity, a few days 

 since, of examining five or six specimens of the brown coal from 

 the Denver Basin, and they have precisely the appearance of the lig- 

 nite on the Yellowstone and Missouri Hivers, which has long since 

 been shown to be of tertiary age. During the autumn and winter of 

 1859-60, while connected with the expedition to the head-waters of 

 the Missouri and Yellowstone, under the command of Colonel Wil- 

 liam F. Raynolds, United States Engineers, Dr. Hayden traced the 

 lignite tertiary formations of the Missouri River to a point near the 

 base of the Laramie Mountains, about eighty miles northwest of 

 Fort Laramie. Here the lignite beds are overlapped and hidden 

 from view by the white marls and clays of the White River Tertiary 

 basin. During the winter Dr. Hayden traced these White River 

 beds along the foot of the mountains southward a short distance be- 

 yond Cache la Poudre Creek, but did not observe that the lignite 

 beds reappeared. At Platte Bridge, on the north fork of Platte 

 River, about one hundred and twenty miles northwest of Fort Laramie, 

 a bed of quite pure lignite, four feet thick, is revealed by the river. 



