130 ENVIRONMENT OF VERTEBRATE LIFE, ETC. 



"The total thickness of this formation is approximately 2,200 feet in the western 

 part of the Uinta Range and about 1,600 feet in the vicinity of Green River. 

 Powell gives the thickness in the east end of the range as 1,000 feet or more." 



Schultz here discusses the possibility of an unconformity at the base 

 of the Weber and decides that no such unconformity exists. 



(g) Conditions in IdaJio. — The Weber quartzite extends into southwestern 

 Idaho, where it undergoes a considerable change, indicating an approach to 

 its northwestern limit. Richards and Mansfield^ describe it as follows: 



"The Weber quartzite in the area examined in 1909 consists chiefly of massive 

 white quartzite with subordinate amounts of shale and calcareous sandstone or 

 limestone. In the region studied during the present year the conditions are 

 practically reversed, and the true quartzite Is subordinate to calcareous sandstone 

 and limestones. The character and position of the small amount of quartzite 

 present are extremely variable. * * *" 



{h) Cojiditions in Wyoming. — In southwestern Wyoming the Weber con- 

 sists of gray and white quartzitic sandstone, often brecciated, reaching a 

 thickness of 500 ± feet. Veatch says of this area:^ 



"From this time [Pennsylvanian] until late Cretaceous there was no profound 

 disturbance. The strata, so far as can be seen, are entirely conformable and the 

 series is complete, but the absence of beds found in other portions of the Rocky 

 Mountains suggests that there were land periods during this interval, produced 

 by broad orographic movements without pronounced deformation in this area. 



Blackwelder has given a more detailed discussion of the Weber and 

 adjacent formations in Wyoming.^ 



"Above this limestone [the Madison, MIssissIppian] is a sandy series, which 

 Is somewhat variable in different parts of the region. The larger part of it com- 

 prises the Weber quartzite In southeastern Idaho and Utah and the Tensleep 

 sandstone In central Wyoming. Its basal portion generally contains beds of 

 red shale and purple or gray limestone, and where thus developed in Utah has 

 been called the Morgan formation, while in eastern and north-central Wyoming 

 Darton has named the corresponding beds the Amsden formation. The upper 

 and larger part of the sandy series is generally a massive yellowish or cream- 

 colored sandstone (Tensleep) In the east, or a quartzite (Weber) In the southwest. 

 On account of resistance to erosion the outcrops of the Weber, Tensleep, and 

 equivalent rocks are almost invariably marked by ridges or peaks, and In canyons 

 by cliffs. * * * 



"Between these two conspicuous horizon markers, the yellow sandstone below 

 and the red shales above, lie the less-resistant strata which Include the phosphate 

 beds. In north-central Wyoming, where these strata are relatively thin, Darton 



' Richards, R. VV., and G. R. Mansfield, Preliminary Report on a Portion of the Idaho 

 Phosphate Reserve, U. S. Geological Survey, Bull. 470, p. 385, 1910. 



'^ Veatch, A. C., Geography and Geology of a Portion of Southwestern Wyoming, U. S. 

 Geological Survey, Professional Paper No. 56, p. 49, 1907. 



' Blackwelder, Eliot, A Reconnaissance of the Phosphate Deposits of Western Wyoming, 

 U. S. Geological Survey, Bull. 470, p. 458, 1910. 



