STRATIGRAPHIO SECTIONS IN UTAH AND ARIZONA. 



57 



part of the formation has been -altered locally 

 by mineralizing solutions and bears deposits 

 of copper of commercial value.' Below this 

 soft, porous altered zone the beds consist of 

 hard limestone apparently somewhat less 

 massive and less silicified than the beds in the 

 Virgin River narrows, with a few rather heavy 

 beds of calcareous sandstone near the top ftiat 

 are very similar to the beds of calcareous sand- 

 stone and arenaceous limestone seen at the top 

 of the Redwall limestone on the rim of the 

 Grand Canyon at the mouth of Toroweap 

 Valley. The thickness was not determined 

 but is more than 1,500 feet. 



Longwell- divided the limestones beneath 

 the Supai sandstone in the Muddy Mountains 

 of Nevada into tlii^ee formations. The upper- 

 most, the Callville limestone, contains Penn- 

 sylvanian fossils and may in part represent 

 what is here called Redwall limestone. 



SUPAI FORMATION AND COCONINO SANDSTONE. 



The names Supai formation and Coconino 

 sandstone were applied by Darton'' to parts of 

 the "Aubrey sandstone" of the earlier students 

 of the region. In the Sliinumo ciuadrangle, 

 Ariz.^ (see fig. 10, locality 23), the Supai for- 

 mation consists of hard fine-grained cross- 

 bedded red sandstone with interbedded red 

 shale and, in the lower 100 feet, interbedded 

 hmestone, the whole series 850 feet thick, 

 overlain by soft red shaly sandstone and red 

 shale 400 feet tliick, a total thickness of 1,250 

 feet for the formation. It is locally as much as 

 1,400 feet thick. The Supai formation is 

 overlain by the Coconino sandstone, a massive 

 buff to creamy-wliite sandstone, very fine and 

 even grained and apparently in a single bed 

 250 to 350 feet thick. 



In Kanab and Hacks canyons (section 1, 

 p. 69) the Supai formation is composed entirely 

 of brick-red sandstone and shale more than 

 1,100 feet tliick. In the upper part of Hacks 

 Canyon the Coconino sandstone consists of a 

 massive white friable saccharoidal sandstone 

 with a deep-yellow to buff sandstone above it 

 and a pale-yellow sandstone beneath, the 



1 Butler, B. S., and others, Ore deposits of Utah: U. .S. Geol. Survey 

 Prof. Paper Ul, pp. 595-597, 1920. 



3 Longwell, C. R., Geology of the Muddy Mountains, Nev., with a 

 section to the Grand Wash ClitTs in western Arizona: Am. Jour. Sci., 

 5th set., vol. 1, p. 46, 1921. 



"Darton, N. H., A reconnaissance of parts of northwestern New 

 Mexico and northern Arizona: U. S. Geol. Survey Bull. 436, pp. 25-27, 

 1910. 



* Noble, L. F., The Shinumo quadrangle. Grand Canyon district. 

 Ariz.: U. S. Geol. Siu-vey Bull. 549, p. 6S, 1914. 



whole formation 90 feet thick. The upper 

 deep-yellow member is present only in the 

 upper part of the canyon, wedging out at a 

 point about 6 miles from the mouth of the 

 canyon on Kanab Creek. In Toroweap Canyon 

 (section 2, p. 69) the Supai formation is all 

 i-ed and 1,300 feet thick, and the Coconino 

 shows an upper deep-yellow la^^er, a middle 

 wliitish layer, and a lower paler-yellow layer, 

 the whole 96 feet tliick. In Black Rock 

 Canyon (section 4, p. 70) the Coconino and 

 Supai were not differentiated, but an exposure 

 of 1,200 feet contains mainly yellow beds 

 separated in the interval from 200 to 500 feet 

 beneath the top by soft brick-red sandstones. 

 At the mouth of Rock Canyon (section 7, 

 p. 71) an exposm-e of 500 feet of sandstone 

 shows mingled red and yellow beds except for 

 the upper 17 feet, wliich contains the apparent 

 ecjuivalent of the Coconino — an upper deep- 

 yellow bed, a middle wliite bed, and a lower 

 yellow bed. At the locality 6 miles south of 

 Hurricane (section 8, p. 71; PI. IX, ^4, B) an 

 exposure of 250 feet of sandstone is mostly 

 yellow, but the upper 65 feet contains an upper 

 yellow layer 20 feet tliick underlain by a white 

 sandstone 45 feet thick, which may represent 

 the Coconino sandstone. In Virgin Narrows 

 (section 19, p. 75) the Supai is a massive sand- 

 stone 1,450 feet thick with considerable irregu- 

 lar red staining in the middle part. The color 

 of the staining is not a deep red and at many 

 points is really a pink. The 45 feet of beds 

 above this unit consist of an upper deep- 

 yellow sandstone, a middle white sandstone, 

 and a lower cream-colored sandstone and prob- 

 ably represent the Coconino sandstone. In 

 the section on the iViTowhead Trail through the 

 Beaverdam Mountains (section 20, p. 76) the 

 Coconino and Supai are represented by a veiy 

 massive sandstone 1,400 feet thick that is 

 predominantly of a pale-yellow color with local 

 pinkish patches. In brief, the red shale and 

 sandstone of the typical Supai formation and 

 the typical white Coconino sandstone grad- 

 ually change toward the northwest into a mas- 

 sive yellow sandstone with no real red and 

 only a little pink coloring. The total thickness 

 of sandstone seems to vary but little in the sec- 

 tions examined, tliough the apparent eciuivalent 

 of the Coconino sandstone tliins steadily. 



Longwell's work ^ in the Muddy Mountains 

 of Nevada and the Virgin Mountains of Arizona 



■'■ Longwell. C. R., op. cil., p. 47. 



