GEOLOGICAL SURVEY OF THE TERRITORIES. 181 



the threshold of our own era, the conditions are similar in many respects 

 to those which produced the long ago carboniferous age ; the same 

 great cretaceous sand formation ushering in the coal as the Pennsylvania 

 No. 10 did the false coal measures and the great conglomerate the real 

 ones. Here also we see mammoth veins and small veins, indicating a 

 longer or shorter period of deposition or a greater or less activity in 

 vegetable growth. Here, too, anthracites and semi-anthracites have been 

 reported, but occupying areas much more geographically restricted than 

 is the case in Pennsylvania. And stranger than all, here, too, are oil 

 wells, apparently the product of this same coal age, but whose supply 

 has trickled through the loose cretaceous and Jurassic formations and 

 found lodgment only in the impervious triassic beds, perhaps on the 

 granite itself. It has been stated above that these coals belong in the 

 main to the class of the bituminous coals, both by right of their chemical 

 constitution and their physical properties. All the specimens, from what- 

 ever quarter, which were obtained by your expedition belong to the bitumi- 

 nous class, so that the inference seems fair that only the middle member 

 of the Pennsylvania series of anthracite, semi-anthracite, semi-bituminous, 

 bituminous, and hydrogenous are represented to any extent in this por- 

 tion of the Eocky Mountains. On the other hand Dr. Le Conte, in his 

 report, mentions a true anthracite, (88 to 91 per centum of fixed carbon,) 

 and Hollister in his " Mines of Colorado," (tlie mineralogical part of 

 which was written by Mr. J. Alden Smith) speaks of albertine coal as 

 occurring in certain parts of western Colorado. Albertine coal (or solid- 

 ified petroleum, as it is sometimes improperly called) is one of the most 

 hydrogenous coals known, and if it really exists, as Professor Denton of 

 Massachusetts asserts it does in White Eiver in West Colorado, the 

 extremes and middle members of the series are to be found west of the 

 Missouri. Still the general character of these coals is bituminous. The 

 following are some analyses of them. 



Bituminous coal front Old Placer Mines, San Lasaro Mountains, New 

 Mexico. — This coal differs in appearance from all other coals found on 

 the flanks of the Eocky Mountains, both in color and fracture. The 

 former is jet black except on the conchoidal cleavage surfaces, where 

 the half metallic bronze lustre, similar to that of the anthracites, is 

 observable. Fracture conchoidal and uneven, splintery ; specific gravity 

 less than that of the Pennsylvania anthracites. 



Milligram. 



Weight in air of specimen 338. 6 



Weight in water with plat wire after boiling 110. 



Weight of wire 7 milligrams, allowing for 1 milligram loss of weight of plat 



wire in water, 6 milligrams 104. 



338.6—104.0=234.6. 

 338.6-^234.6=1,443.3 specific gravity. 



First analysis : 



Per cent. 



Water and volatile substances 22. 



Ash 8.2 



Fixed carbon 69.8 



Total 100.0 



Second analysis : 



Water 3.0 



Volatile substances 21.0 



Ash 7.5 



Fixed carbon 68.5 



Total 100.0 



