|
58 MINERAL RESOURCES.
|
||
|
|
||
|
profitably treating auriferous sulphurets, which has so often proved an insurmountable obstacle to the continued development of gold mines. This obstacle has, however, already been successfully overcome in the Treadwell mine by the adaptation of the chlorination process.
The annual product of the Territory, which is given as exclusively gold (the silver product being comparatively insignificant) shows a steady increase during the decade. Tlws increase is remarkable rather for its regularity than its amount and is hence of more favorable import for the permanency of the development of the mineral resources than would be one subject to violent fluctuations, for while the discovery of exceptionally rich ore bodies undoubtedly causes a rapid development of the district in which they occur, the reaction which follows the inevitable exhaustion of such bodies may more than counteract the good effect which they have had, so far as its permanent prosperity is concerned.
|
||
|
|
||
|
|
||
|
|
||
|
ARIZONA.
But little is known with certainty about the geological relations of the ore deposits of Arizona, no systematic geological studies yet having been made of the Territory as a whole, nor of any of its rich mining districts. As its name indicates it is a generally arid region, the aridity increasing from the east, westward and southward, the western part of the Territory, though traversed by the Colorado river, having the desert features that characterize the greater part of Nevada.
The northeastern portion forms part of the Colorado plateau, about one-third of which is included within the boundaries of Arizona. It is an elevated region supporting some forest growth, and as contrasted with the rest of the Territory is fairly well watered. To the southwest of the plateau region are a series of narrow isolated ranges separated by broad arid valleys, similar to the basin ranges of Nevada, with which, by their general north westerly trend, they are connected. They are made up generally of Paleozoic strata resting on a basement of crystalline rocks, and traversed to a greater or less extent by eruptives. The intervening valleys in general increase in width to the southwest, approach more and more to sea level, and Paleozoic strata disappear, the rocks being mainly granites and schists. Coal-bearing rocks appeal to be entirely wanting. Under such physical .conditions mining and pastoral pursuits are the only self-supporting industries. Two trans-
|
||
|
|
||