DETAILS OF THE EED VALLEY. 145 



standing the breadth of the exposure of the red clay — or rather perhaps 

 because of the breadth — it is impossible to measure its thickness. The 

 best estimate practicable seemed to indicate a thickness of between 250 

 and 300 feet. In many places the clay is quite sandy, especially in 

 the eastern part of the valley where it sometimes becomes a soft argil- 

 laceous sandstone marked in the topography by hillocks and small buttes 

 and mesas. 



The junction of the Red Beds with the overlying Jura is well seen in 

 many places along the foothills north of Redwater Creek. Several sec- 

 tions of the Jurassic rocks, including their relation to the Red Beds, were 

 measured by Mr. Jenney and Mr. Patrick and will be found in the section 

 on the Jura. 



Southwest of Sun Dance and west and northwest of Inyan Kara there 



is a long range of low foothills cut by parallel valleys running north and 



south which carry in their bottoms red clay and on their sides the lower 



strata of the Jura. At one locality southwest of Sun Dance the following 



section was observed: 



Jura. 



Feet. 



7. Slope of hill ; no exposure 25 



6. Sandstone, very soft, white and yellowish ; well exposed for 10 feet, in the 



remaining distance fragmentary outcrops of soft white sandstones 75 



5. Shales, brown and yellow, sandy, containing Belemnites, Gryphcea calceola, 



etc . 65 



4. Sandstone, soft, white 10 



3. Clay or marl, yellow or reddish 50-60 



Bed Beds. 



2. Gypsum 6-8 



1. Clay, red — 



In Figure 23 an attempt is made to illustrate the relation of the Red 

 Valley and the Red Beds to the volcanic intrusions. The section runs from 

 Warren Peaks in a southeast direction to the Carboniferous plateau, cutting 

 on the way one of the Sun Dance Hills. It will be noticed that the Red Beds 

 rest directly against the trachyte of the Sun Dance Hills, while at Warren 

 Peaks the Carboniferous and Potsdam are interposed. If the Sun Dance 

 Hills be omitted and the red clay (5) extended across the space, the sec- 

 10 B H 



