472 THE POPULAR SCIENCE MONTHLY. 



It is manifest that if this process be continued, and if all the hills 

 are like that described, the reduction of all these terraces and mounds 

 is but a question of time, and we may look forward to the day when 

 all this now wild and impassable country shall be but a prairie of gen- 

 tle undulations and monotonous outlook, not dissimilar to the wide 

 plains which even now stretch off far to the east to blend with the 

 Missouri Valley. Every mountain shall be made low and every valley 

 filled, and no force more violent be concerned than the gentle action 

 of the wind and rain. 



I have said that the detritus of the storm is non-precipitate, is 

 borne away by the water ; and yet some of the moving particles do 

 find lodgment by the way. There is no such thing as a talus at the 

 foot of the bluff, but after each flood a thin film of fine silt is spread 

 over the plain, and the flat bottoms of the ravines are by impercepti- 

 ble pace forever creeping up the wasting buttes, particularly of those 

 remote from the river. 



But such a butte as that described, while revealing much, does not 

 reveal all the facts necessary to the full understanding of our subject. 

 One of the first things to strike the attention of the tourist among the 

 hills is the evidence of the wide-spread action of powerful heat. The 

 bands of red which everywhere mark the landscape are certainly traces 

 of some glowing fire. But what a fire ! Here are whole beds of clay 

 baked until they have taken on the color and character of hard -burned 

 brick or unglazed pottery. The resonance of the dry fragments under 

 the hammer or the wheels of our vehicle is precisely that of broken 

 terra-cotta. Sometimes the top of the butte is bare and red ; some- 

 times the whole mass, from top to bottom, has been burned, and at a 

 distance seems like a brick-kiln fallen into ruin. The splintery frag- 

 ments, broken as macadamizing stone, form over the entire surface a 

 natural riprap, on which the elements spend their force in vain. Such 

 buttes are not transient ; the fire has saved them, and in this diy cli- 

 mate they may stand forever. Here and there, so hot has been the 

 fire, that the clay has been not only baked but fused, and great clinker- 

 like masses rest upon the hill-top, thrust themselves out from the hill- 

 side, or stand naked like monuments on the plain. 



In looking for the source of heat capable of producing such phe- 

 nomena men seem instinctively to revert to volcanic fires, and the burned 

 clay is everywhere designated scoria. In one place where the railroad 

 cuts through a hill of this material we have " Scoria Cut," and scoria 

 constitutes for miles the favorite ballast. But probably volcanic fires 

 were never nearer than at present. Of crater, lava, trap, or other 

 usual volcanic concomitants, there is not the remotest sign ; but to-day, 

 while we are theorizing over the matter, some of the furnaces which 

 have baked all these regions are still glowing, the smoke yet ascends, 

 and our own eyes may witness something of the transformation. The 

 lignite-beds furnish the fuel, the slow-paced erosion lays the fuel bare, 



