GEOLOGY OF THE HIGH PLATEAUS. 



BY CAPT. C. E. DUTTON. 



CHAPTER I. 



GENERAL CONSIDERATIONS RELATING TO THE TOPOGRAPHY AND GEOLOGICAL HIS- 

 TORY OF THE HIGH PLATEAUS AND THEIR RELATIONS TO THE PLATEAU PROVENCE 

 OF WHICH THEY FORM A PART. 



Situation of the Higli Plateaus. —The westernmost range comprising the Pavant, Tushar, and Markii- 

 gunt. — Sevier Valley. — The second or middle range comprising the Sevier and Paunsagunt Pla- 

 teaus. — Grass Valley. — The third range comprising the Wasatch, Fish Lake, Awapa, and Aquarius 

 Plateaus. — Structural features of the Park, Plateau and Basin Provinces. — The High Plateaus form 

 the western district of the Plateau Province. — Relations of the High Plateaus to the Plateau Province 

 at large. — Geological history in outline during Cretaceous time. — Interruption of continuity be- 

 tween the Upper Cretaceous and Tertiary. — Unconformity between Cretaceous and Tertiary. — Early 

 Tertiary history. — The lacustrine condition of the entire Plateau Province during early Eocene 

 time. — Gradual desiccation of this Eocene lake. — Cretaceous-Eocene strata occupying its locus 

 at the close of the Eocene. — Their vast bulk and gradual subsidence pari passu with deposition. — 

 The counterpart of this subsidence, viz, the elevation of the surrounding mountain chains. — 

 Post-Eocene history. — Erosion. — Its conspicuous display and the certainty of its evidence. — The 

 drainage system of the Colorado River. — Its origin. — Its stability of location. — Priority of drainage 

 channels to structural features. — Their persistence.— The methods of erosion. — Centers of erosion 

 and the recession of cliffs. — The San Rafael Swell. — Vastness of the results accomplished by 

 erosion. — Effect of the removal of great bodies of strata from large areas. — The erosion chiefly 

 accomplished in the Miocene. — Summary of the relations of the High Plateaus to the Plateau 

 country at large and to the Basin Province adjoining them on the west. 



The region to be discussed in this work is centrally situated in the 

 Territory of Utah, occupying a belt of country extending from a point 

 about 15 miles east of Mount Nebo in the Wasatch, south-southwest, a 

 distance of about 175 miles, and having a breadth varying from 25 to 80 

 miles. The total area of this field of study may approach 9,000 square 

 1 H p 



