THE BASIN PROVINCE 161 



Float of buff sandstone and shale, becoming more shaly and calcareous at base 104 



Siliceous arkose comprising mainly rounded quartz grains and feldspars cemented with ferruginous 



material 18 



Compact grayish quartzite 20 



White compact sugary sandstone fossiliferous at base 8 



Fine gray and pink massive quartzite with brown sandstone and gray-white chert bands near base ... 30 

 Light-gray limestone weathering whitish gray with an imbricated pattern; fine gray lime near base 



carries good faunas at two horizons in particular, 20 and 55 feet above the base 27 



Gray calcareous sandstone 24 



Fine gray limestone 9 



Float showing bits of grayish and brown calcareous sandstone 36 



Sandy limestone more calcareous at base wdth cavernous weathered surface 22 



Float ; upper sandy beds at top of Weber quartzite 31 



^^ Deposition. — The conditions which prevailed during the deposition of this 

 formation, a few hundred feet in thickness, marked the transition from those 

 under which the great thickness of sandstone had been laid down to those which 

 followed, when the sediments formed red shale. The composition of the lime- 

 stones, sandstones, and shale points to their deposition in comparatively shallow 

 water and the limestones contain shallow- water remains. The repeated alterna- 

 tion of these lithologic types shows unsettled conditions either as regards elevation 

 or deposition along shore, and it is probable that both occurred. 



''Age and stratigraphic relations. — The fauna of the Park City formation, 

 which is better known from areas in Idaho, Wyoming, and other parts of Utah 

 than from the Park City district itself, may be properly limited to two facies — 

 one which is best known in the dark phosphatic and calcareous shales around 

 Montpelier, Idaho, and one which occurs in the limestones that at some points 

 overlie these shales and at others seem largely to replace them. The fauna of the 

 phosphate shales and limestones has been described in United States Geological 

 Survey Bulletin 436. The fauna of the limestones is characterized by the remark- 

 able species Spiriferina pulchra, with which are associated types of Productus, 

 Bryozoa, etc. Both faunas are suggested by the collections from the Park City 

 district, the one by more or less abundant Lingulidiscina utahensis, the other by 

 spiriferinas, probably referable to 6*. pulchra. The age of these faunas is now 

 provisionally determined as Permian. 



"No unconformity was observed with the underlying Weber quartzite or the 

 overlying shale or within the formation. Accordingly it would seem that sedi- 

 mentation proceeded unbroken from Mississippian time through that part of the 

 Pennsylvanian which is represented by the Park City formation." 



"The conditions which prevailed during the closing part of Permian time, as 

 shown by the alternating limestone, sandstone, and shale of the Park City 

 formation, were at different stages those of sea bottom, shallow shore bottom, and 

 exposed shore with mud flats." ^ 



The Permo-Carboniferous age of the Woodside member of the Park City 

 formation was demonstrated by Girty,^ who writes : 



"The three members of the Park City formation vary from point to point 

 in lithology and in thickness, as well as in fauna. In the Montpelier district the 

 upper limestone marks an important horizon for determining the position of the 

 phosphate deposits. It is massive, contains here and there much black chert, 



1 Boutwell, J,. M., U. S. Geological Survey, Professional Paper No. 77. p. 104. 



^ Girty, G. H., The Fauna of the Phosphate Beds of the Park City Formation in Idaho, 



Wyoming, and Utah, U. S. Geological Survey Bull. 436, p. 6, 1910. 

 12 



