STRUCT OB.- A L CHARACTERISTICS OF THREE PROVINCES. 29 



the parky, as these interspaces are often called, is exceedingly complex, and 

 much study is necessary, and a great accumulation of facts must be obtained 

 before any safe generalization can be made ; but these interspaces or park 

 areas are sometimes Zones of Diverse Displacement. 



Atlas Plate No. G presents a section across three of the great ranges of 

 the Park Province. This section has been prepared for me by Mr. Marvine. 

 The scale on which it is drawn does not admit of great detail, but the gen- 

 eral orographic characteristics are well represented. In a single section it 

 is impossible to present all of the facts upon which this generalization is 

 based. In the quotation from Mr. Marvine already given some of the facts 

 on which his opinions are based appear, and I have myself seen patches of 

 sandstone high up on the Front Range in the vicinity of Long's Peak, and 

 also on the northern end of the Park Range in an area of country not visited 

 by Mr. Marvine, but the shreds of evidence are too multifarious to be assem- 

 bled here. The park spaces between the great ranges are seen to be com- 

 plex in the section, but the full extent of this complexity could be illustrated 

 only by the most full and graphic representation. Doubtless when the 

 reports of the several members of the First Division of the United States 

 Geological and Geographical Survey of the Territories are published, the 

 general structure of this country will be more fully revealed. 



I have quoted Mr. Marvine and discussed this subject with him more 

 fully from the fact that he and I have visited many of the same points. 



I have not myself studied the eruptive mountains of this province. 



SUMMARY OF THE STRUCTURAL CHARACTERISTICS OF 

 THE THREE PROVINCES. 



The Basin Province is characterized by north and south ranges that are 

 monoclinal ridges of upheaval, and these monoclinal ridges are separated by 

 stretches of subaerial gravels that mask the structure of the areas of subsi- 

 dence. But while this is the prevailing structure, other types are found. 



In the Plateau. Province the Kaibab structure is the characteristic. 

 Here on a grand scale the primary and concomitant forms are found; but 



