122 REPORT UNITED STATES GEOLOGICAL SURVEY. 



COAL AND IRON. 



Coal occurs in Colorado at a number of localities ; it is found, with 

 interruptions, along the eastern base of the Front Kange, and in the 

 interior of the State in valleys of many of the larger streams or their 

 drainage. In 1873 and 1875 I visited the coal mines of Canyon and 

 Trinidad, which lay within the borders of my districts. At both places 

 I found an ample supply, and found mining-operations going on. About 

 the quality cf the coal much has been said and written. It is useless to 

 repeat anything here; the object of this paper cannot permit it. Suffice 

 to say, that for ordinary economic purposes the coal will answer very 

 ■well. An almost unlimited source of coal may be developed in Colo- 

 rado if all of its available beds are developed. Many years must nec- 

 essarily pass, however, before this will be required. A brief reference 

 may be made to the " anthracite," which has often been reported from 

 this State. So far as the observations of geologists of this survey go, 

 the anthracites are either older (lowest Cretaceous) coal than the " lig- 

 nites," or they owe their anthracitic composition to the passage of vol- 

 canic material through the beds or seams. In this latter case the heat 

 of the volcanic rocks has caused a partial volatilization of the gases, 

 thus greatly increasing the percentage of fixed carbon. It is evident, 

 therefore, that although we may have an anthracite in the strict miner- 

 alogical application of the term, we have not an anthracite in the same 

 sense of the word as it is applied, for instance, to the Pennsylvania 

 coal. 



Iron is found and mined in Colorado on Grape Creek, near Canyon 

 City. The ore is magnetite, yielding a high percentage of the metal. 

 But little demand for iron exists in the State at the i)resent time. 

 Should the demand arise, however, numerous deposits, now undisturbed, 

 will furnish ample material to meet it. Limonites occur as kidney ore 

 within the same beds that contain the coal, and if uudecomposed, they 

 are siderites. At Golden, Canyon, and Trinidad they are found, and 

 can readily be utilized if required. In the interior of the State certain 

 formations usually carry lower-grade iron ores, which may, at some 

 future day, perhaps, be turned to account. 



In order to present a brief synopsis of all the formations found in 

 Colorado, I have prepared a table. In it is recorded not only my own 

 work, but extracts have been made from the reports of Dr. Hayden, 

 Dr. Peale, Mr. Holmes, Mr. Marviue, and Professor Lesqnereux. It is 

 at all times a matter of considerable difficulty to attempt parallelization 

 of formations or groups. A certain amount of latitude must be admitted 

 for all comparison of such nature. Though but a comparatively small 

 proportion of the formations and groups can be found in any one partic- 

 ular district, the total exhibit is one showing a sufficient diversity. 



Thicknesses of beds and groups have been given, showing the limits 

 that were therein observed. It is evident that over an area of nearly 

 70,000 square miles great variations of the vertical dimensions must 

 occur, and therefore they have been indicated so far as feasible. 



Enumerations of locality are made, beginning with the more westerly 

 ones and going eastward. 



