20 UNITED STATES GEOLOGICAL SDRVEY— TERTIARY FLORA. 



Prof. Clayton, are of considerable importance, the prominent vein of the 

 measure being thirty-two feet in thickness and of excellent quality, But the 

 geological relation of these last lignite deposits is not as yet definitely ascer- 

 tained, some of them being apparently Cretaceous. What I have said is 

 more than sufficient to show the wide extent of the great Lignitic, its average 

 thickness, and also its capacity and importance for the production of coal. 



To ascertain the exact value of the Lignitic coal, numerous chemical 

 analyses have been made and published. An analysis of coal of the Carbon 

 Mines is given already in Dr. Hayden's Annual Report, 1869, p. 197. Mr. J. P. 

 Carson, the chemist, finds in it 51.67 fixed carbon. In Report of 1870, the 

 bituminous coal from the old Placi^re mines of San Lazaro Mountains, New 

 Mexico, is analyzed mostly by Mr. Persifer Frazer, jr., and shows on eight dif- 

 ferent analyses an average of 60 per cent, of fixed carbon; that of Evanston, 

 49. At page 321 of the same volume, there is a very interesting comparative 

 table of the result of chemical analyses of the coal of the more important 

 seams of the southern basin, by Mr. James F. Hodge. From it are 

 derived the following data: — Golden coal, fixed carbon, 45.57 to 47.58; 

 Murphey's Mine, 44.41 ; Marshall's, 49.72 ; Boulder County, 47.30 to 

 50.65; Carbon, 49.72; Rock Springs, 54.46; Evanston, 50; Coalville, 48. 

 From analyses recorded in my Report, 1872, the results are about tlie 

 same. The Carbon coal has of fixed carbon between 49.30 and 51.65; 

 Rock Springs, 52.45; from north of Trinidad a coal, of which I had choice 

 specimens, has of fixed carbon 57.60; Caflon City coal, which is very 

 rich in fixed gas, has 54.70 of fixed carbon, and that of the Raton Mountains 

 55. Most of the analyses quoted here, with a large number of others, are 

 presented in a table of the Annual Report of 1873, pp. 112-114. Though, 

 as everybody knows, the result of analyses present always marked differ- 

 ences, the compounds of each piece of coal taken from a mine being more 

 or less varied, it is evident that the coal of the Western Territories is a lig- 

 nite of high value and of a quality at least equal, if not superior, to the com- 

 bustible mineral generally known and used in Europe under the appellation 

 of lignite. The highest average of fixed carbon in European lignite is 67 to 

 68, and this very rarely; it generally averages 45 to 46. This subject, how- 

 ever, need not be considered further. Its relation to the fossil flora is far 

 indeed, and it is sufficient to touch it in passing in order to omit nothing 

 which may afford some knowledge of the characters of the Lignitic. 



