GENERAL STKUCTUBE 443 



The region was upheaved partly as an integer and partly as a body of 

 minute parts. With upheaval degradation progressed. We are led to 

 conclude that a maximum rate was not established; that as upheaval was 

 slow, degradation was slow. 



Berkey (8) notes the occurrence of a persistent and important fault on 

 the upper Duchesne, and states that toward the east the major fault cuts 

 higher up in the series, at least above the Carboniferous. 



Faults are of frequent occurrence along the strike of the Cambrian 

 shales, which seems to have been a line of weakness. In some instances 

 the fault is a normal one; in others the overlying limestones appear to 

 have been thrust over and covers in whole or in part these shale beds. 

 Where the shale beds are not faulted the strain seems to have been relieved 

 by compression in the Weber and overlying Permo-Carboniferous strata. 

 As a rule, the Paleozoic beds have a shallow dip 12 to 20 degrees, while 

 the Mesozoic beds which form the outer slopes of the fold usually dip at 

 40 degrees. On the northern slope, in the central region, the "Uinta" 

 quartzite and overlying Cambrian and Carboniferous beds are steeply up- 

 turned, while in the eastern areas the "Uinta" is nearly horizontal or dips 

 5 degrees or less, and the higher beds are faulted or steeply upturned. 



OENERAL STRUCTURAL FEATURES OF SOUTHERN SLOPE 



The fault which crosses the Duchesne river at the mouth of Iron creek 

 is a normal one. At the head of the West fork of Kock creek the same 

 fault has developed into a thrust. On the West fork of Lake fork the 

 fold is symmetrical, except that the Weber and Permo-Carboniferous 

 strata have been sharply plicated and compressed. The section in White- 

 rocks canyon exhibits similar plications in the same strata, and there is 

 also a small amoimt of faulting in the shale series. 



Subsequent' to the main folding there has been a warping by which the 

 general east-west strike varies from northwest-southeast to northeast- 

 southwest at various localities. 



GENERAL STRUCTURAL FEATURES OF NORTHERN SLOPE 



The general east-west strike of the beds varies locally as on the south- 

 ern slope. 



Where the Weber river cuts through the Paleozoic strata the beds dip 

 80 degrees north, and in the Weber formation there is developed locally 

 an overturn of these strata. In this region the strata of the "Uinta" 

 formation dip 5 to 10 degrees to the north, with a sudden steepening of 

 dip in the beds beneath the shale series. To the east the inclination of 

 the "Uinta" strata increases in the direction of the axis of the range. 



XXXVIII — Bull. Geol. Soc. Am., Vol. 18, 1906 



