TERTIARY COAL MEASURES OF GUNNISON COUNTY, COL. 689 



description of the characteristics of other sections, that the difference may be 

 realized. 



Take the first openings back of Crested Buttes town, and to my amazement 

 the coal lay upon shale, with a solid sandstone roof; and for 1500 feet thick, as 

 these measures appear to be, the rock formation is shale, coal, and sandstone ; no 

 limestone belongs to this series, and nowhere does any animal life appear to have 

 existed in the waters that deposited the sediments making the present existing 

 sandstones and shales. All other coal measures known have most abundant re- 

 mains of shell-fish in the limestones, sandstones, and shales of their respective 

 ages. 



The only fossils are the impressions of leaves of land plants and trees that 

 floated out to sea, sank, and left a record in the sands, saying here was a tropical 

 climate, as most beautiful palm-leaf impressions are obtained in one horizon, as 

 well as many other leaves grown in a like latitude or climate, whose names I do 

 not know. 



The sandstone itself is a marvel, in places many feet thick, and repeated just 

 the same many times in different strata ; as, in looking for a cause that would ac- 

 count for the absence of life in these waters, I found the sandstone was not the 

 detritus from the wearing away of other rocks, but was a precipitation of particles 

 of quartz from a hot sea, carrying an excess of silica in solution, cemented by a 

 small amount of material that was produced from dissolved feldspar ; not a round- 

 ed pebble in the whole series, but even-grained and homogeneous throughout. 



I examined 100 square miles of these measures, and in the midst of it all 

 found 2000 acres of anthracite coal, the finest of its kind known on the continent, 

 a four foot vein, giving from 90 to 94^ per cent of fixed carbon and no iron or 

 sulphur in an appreciable quantity. 



To finish with, 1000 feet of conglomerate had at one time been deposited over 

 the whole of this, and in another locality recent lavas were found overlying these 

 Tertiary sandstones. 



If the above, which can be seen by any one, was not a geological problem, 

 I have never met one. To solve it, I had to find the rocks of the next oldest 

 age, which proved to be Cretaceous, large shale beds of this age existing partly 

 metamorphosed to a slate, and containing the characteristic fossil — Inoceramus — 

 of the Cretaceous seas. 



The closing of this age gave me the key to very much, as locally it is marked 

 by one of the most stupendous eruptions of volcanic paste that ever was known, 

 covering hundreds of square miles on a Cretaceous sea-bottom, not only flowing 

 over these muds, where lived the Inoceramus. but also elevated in enormous mass- 

 es, which now show as mountain ranges, as well as single mountains or cones. 

 This volcanic mass is now geologically identified as granite porphyry, its constit- 

 uents being siUca, horn-blende, feldspar, a small amount of mica, and occasion- 

 ally a small crystal of sanidine. The feldspar separated into beautiful crystals, 

 with perfect sides and terminations, some of them of large size, held most firmly 

 by the silica which makes the bulk of the paste. So much harder is this inclos- 



