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Show xvi GEOLOGY OF THE HIGH PLATEAUS. intimate relations. In the brief season during which work in such a region is practicable the investigation must be pushed with the utmost vigor and rapidity, and the greatest portion of the time must be devoted to acquiring a general and connected view of the broader features, while details cannot often receive the attention which their importance really demands. From the nature of the case, therefore, the work must be somewhat superficial in many respects. In preparing a monograph upon this district, it has been necessary to lay the greatest stress upon a few subjects of inquiry, and these would naturally be those which the facts most fully exemplify. It was important, however, at the beginning to discuss it as a part of a great geological province, in which are found certain categories of facts possessing a peculiar interest, displayed in a remarkable manner, and of the highest importance to physical geology. The "Plateau Country" of the west is, I firmly believe, destined to become one of the most instructive fields of research which geologists in the future will have occasion to investigate. Of its subdivisions the District of the High Plateaus is one of the most important, and the relations of the district to the province were studied with great care. The results of those studies are set forth in general terms in the first two chapters. In the treatment of geological phenomena occurring within the district the investigation has been devoted chiefly to three lines of inquiry. The first is geological structure-those attitudes of the strata and the topographical forms which have been caused by the vertical movements of the rocks. The displacements which have occurred there are very striking both in respect to their magnitude and to their systematic arrangement. In their forms and modes of occurrence they are also somewhat peculiar, especially when brought into comparison with displacements found in other regions. Ultimately such facts must take their place in that branch of geological philosophy which treats of the evolution of the earth's physical features, the building of mountains, and the elevation of continents and plateaus; but at present the observed facts do not appear to group themselves into the relation of effects to causes. The broader facts relating to structure are discussed in the second chapter. |