690 KANSAS CITY REVIEW OF SCIENCE. 



ing paste that it was difficult to get good specimens of the crystals, the latter de- 

 composing more readily, and leaving perfect casts in the rock. 



This granite porphyry would make the most beautiful building stone, as it is 

 more easily quarried than Maine granite, more readily dressed, is just as durable, 

 will take as high a polish, and when finished is as beautiful as any marble known, 

 has no mineral constituents to oxidize and stain, and is in inexhaustible quanti- 

 ties. It comprises such mountains as Crested Buttes, Gothic, Carbon, Edgely, 

 Beckwith, and Marcellina, as well as the ranges known as Ragged Mountains, 

 the Anthracite range, and Wheatstone group. Near to part of these now run two 

 railroads, and in time along these lines will be mammoth quarries ; for here is a 

 better rock to send East than the East can possibly send West. 



The next move of nature in this locality was to elevate these submarine 

 mountains above sea-level, so that shallow marshy seas were at their bases. The 

 climate was at this sea-level, I think, more tropical than anything that we are 

 acquainted with at the present time ; as not only was the latitude such as to have 

 hot seasons, but, in addition, towering up thousands of feet in every direction, 

 were these mountains of volcanic material, giving off large volumes of heat by 

 radiation ; large masses of volcanic rock cool slowly in the atmosphere. In the 

 gorges and open shallow seas of this Tertiary age, at the feet of these mountains, 

 and among all of this warmth — and very great moisture there must have been in 

 the atmosphere, too — commenced the growth of the plants that now make these 

 Tertiary coals. How long time is, under such circumstances, as we reckon it, 

 we can have no data ; but sufficient was the period of rest here, for these plant- 

 growths to accumulate several feet thick. 



Here I want to do a little local reasoning, that in principle may apply to 

 other eruptive localities. To begin with, this eruptive matter must have been the 

 product of internal heat below the earth's surface ; the overlying crust must have 

 been proportionably strong to hold such a vast quantity confined, with its cumu- 

 lative force of steam and gas ; when this power had accumulated sufficiently to 

 exert itself, the eruptive power was in ratio to the power used, which again was 

 in proportion to the thickness or resistance of the overlying earth-crust; after the 

 eruption, there would be an internal cavity approximating in size to the cubic 

 contents of the mass recently brought to the surface ; the original surface rocks 

 would have the tonnage to support represented by the mass of eruptive material ; 

 this weight on the underlying shell then became to a greater or less extent plastic, 

 and, without internal support, would cause a local sinking at varying periods, 

 which periods of subsidence were represented by changes in the more recent sed- 

 iments which were afterward deposited on the new floor or sea-bottom ; and each 

 and every one of such changes of sea depths can be counted by the variations in 

 the newer strata of rocks. 



Noting the above reasoning, in these coal basins, we find after a time a sub- 

 sidence, and on top of the coal plants flowed a greater depth of water. The 

 mountains were still hot, the exposed surfaces somewhat decomposed, this influx 

 of water was heated to a great degree and took into solution silica, which com- 



