THE BASIN PROVINCE 159 



E. PERMO-CARBONIFEROUS OF THE NORTHERN PART OF THE 



BASIN PROVINCE. 



A discussion of the Permo-Carboniferous beds of the Basin Province 

 was given by the author in PubHcation 207 of the Carnegie Institution. 

 To this are added recorded observations completing the description and 

 showing the relation of the beds of the Basin Province to those of the Plains 

 Province. 



As has been shown on page 154, the Cutler formation of southwestern 

 Colorado and adjacent parts of Utah show the last traces of the red beds 

 of the Permo-Carboniferous. North and west of this region the equivalent 

 horizon is either absent or is occupied by different deposits. 



The Weber sandstone horizon, traced on pages 120-136, becomes of im- 

 portance about where the Red Beds of Permo-Carboniferous age disappear. 

 It is very possible that it is represented by the Lower Aubrey sandstone of 

 the Grand Canyon section, but it becomes more prominent and definite in 

 Central and Northern Utah and breaks up in southern Montana. Using 

 this well-determined horizon as a guide marking the upper Pennsylvanian, 

 the layers above it are mostly regarded as Permian, or Permo-Carboniferous. 



The condition of the upper beds in the Wasatch and Uintah Mountains 

 is as follows : 



King's description of the upper part of the Weber Canyon section is 

 quoted in Professional Paper No. 71 of the United States Geological Survey, 

 page 377: 



"Conformably overlying the [Weber] quartzite is a very heavy bed of much 

 altered gray limestone from 600 to 700 feet thick. The bedding planes are often 

 entirely obliterated and the material extremely crystalline, showing traces of 

 great interior disturbance. The lower beds show a true conformity with the 

 underlying quartzite. * * * The average colors of these limestones are cream- 

 grays, inclining often to white in the more crystalline portions. * * * Overlying 

 this main body of 700 feet of limestone is a series of yellow shaly limestones 175 

 feet thick. * * * Overlying these calcareous shales, as heretofore quite conform- 

 able, is a series of sand and mud rocks, all more or less calcareous, varying in color 

 from chocolate to olive, with red argillaceous sandstones, the whole about 225 

 feet thick. It has the appearance of a comparatively shallow water deposit, 

 made of argillaceous material, limestone, and sand, the thickness of the individual 

 beds being unusually limited. There are very many beds not over an inch thick. 

 On the upper surface of the strata, at several horizons, ripplemarks are preserved 

 with unusual distinctness and on a scale of fineness not often seen, the distance 

 between the wave and the trough being frequently not over an inch or an inch 

 and a half. Alternating dark chocolate and olive-colored shales form the lower 

 200 feet of this group, while the upper 25 or 30 feet are pretty solid sandstone. 

 Over these, still conformable, are 100 feet of yellow and olive calcareous shales, 

 which are so earthy as usually to decompose, yielding a bad outcrop. Above this 

 is a bed of bluish-gray limestone, rather compact, about 150 feet in thickness. 

 Next comes 20 feet of reddish-brown clayey sand, hardly compacted into rock. 



