54 EXPLOITING EXPEDITION FROM SANTA Ffi 



only here and there dwarfed and scattered pines and cedars and threads of green along 

 the streams; the surface marked with long lines of mesa walls, the abrupt, ofte.n verti- 

 cal sides of broad valleys of erosion; over considerable areas the denudation of soft 

 materials, of varied and vivid colors, having fretted the surface into wonderfully truth- 

 ful imitations of Cyclopean cities, crumbled by 'time, or devastated by fire, giving 

 double force to the sense of desolation which the scene inspired. 



Such, in general terms, are the external features of the plateau country west of 

 the Rocky Mountains, through which the Colorado flows. Perhaps no portion of the 

 earth's surface is more irremediably sterile, none more hopelessly lost to human occu- 

 pation, and yet it is but the wreck and ruin of a region rich and beautiful, changed 

 and impoverished by the deepening channels of its draining streams; the most striking 

 and suggestive example of over-drainage of which we have any knowledge. 



To prevent misapprehension, it should be stated that, around the margins of the 

 Colorado plateau, at the immediate bases of the mountains, the traveler will behold 

 many scenes of beauty and fertility strikingly in contrast with the aspect of the country 

 nearer the river. Here are limited districts deserving our highest encomiums; regions 

 of green and flowery mountain valleys, of clear, cold, and copious streams; of magnifi- 

 cent forests; with an atmosphere of unrivalled purity, and a climate delightfully tem- 

 pered. Here, too, are the mineral treasures of which the sedimentary rocks of the 

 plateau furnish almost none; and here will be congregated the mining population, 

 whose business it will be through future ages to extract for our use the mineral wealth 

 with which many of these mountain ranges are stored. 



Though valueless to the agriculturist ; dreaded and shunned by the emigrant, 

 the miner, and even the adventurous trapper, the Colorado plateau is to the geologist 

 a paradise. Nowhere on the earth's surface, so far as we know, are the secrets of its 

 structure so fully revealed as here. 



I need hardly say that, with the exception of the isolated mountains to which 1 

 have referred, the rocks composing the plateau are sedimentary throughout. They 

 include strata representing the entire Cretaceous formation, the Triassic, perhaps 

 locally, though not yet identified the Jurassic, the Carboniferous, Devonian, and 

 Silurian. In the different parts of its course the Colorado cuts through successively all 

 these strata, and near the western margin of the table-land has worn a furrow (!()') feet 

 deej) in the underlying granite. The sections afforded by the canons of the Colorado 

 and its tributaries reveal in the most clear and unmistakable manner the superposi- 

 tion, thickness, Jind mineral character of the sediments forming the table-land to even 

 the most hurried observer; and when, with time and patience, we shall have collected 

 a full series of their characteristic, fossils there as elsewhere only locally abundant 

 we shall be able to write with unusual fullness and precision both the zoological and 

 physical history of the epochs of their deposition. 



A summary of the results of geological observations made while connected with 

 two expeditions organized for the exploration of the course of the Colorado is briefly 

 as follows : 



The phenomena presented by the geology of the area drained by the Colorado 

 which embraces all Arizona, the western half of New Mexico, and much of Colorado 



