THE BASIN PROVINCE 



147 



northern and central Arizona is the Moenkopie. Darton has given a 

 general review of the Permian of this region/ with a map of the outcrops. 

 He describes the Moenkopie as a mass of shales and sandstones, generally 

 of a red color and very variable in different sections — terminated at the top 

 by a conglomerate, the Shinarump, which is considered as Triassic. 



The following general section of the Moenkopie on the Little Colorado 

 River is quoted from Ward by Darton: 



^ Feet. 



Dark chocolate-brown shales devoid of grit and highly charged with salt and gypsum 200 



Dark-brown soft argillaceous sandstone 100 



Dark-brown shale, highly saliferous and with gypsum layers ; becomes calcareous below 200 



Shale, mostly white 1°° 



Brown shale, similar to those above; saliferous 100 



Carboniferous limestone. 



"The sandstones occur at various horizons and locally attain a thickness of 

 100 feet, with more or less intercalated shale. They are mostly soft, and weather 

 in irregular rounded ledges. The gypsum occurs largely in thin veins, crossing 

 the strata at various angles. Toward the base of the formation the shale is 

 calcareous and nearly everywhere includes a bed of limestone that merges into 

 the inclosing strata." 



The same formation occurs in the Zuni Uplift, at San Jose, Ojo Caliente, 

 and Jemez. 



These beds extend westward beyond the San Francisco Mountains until 

 the last remnants appear in small red hills between Ash Fork, Arizona, and 

 the rim of the Grand Canyon. 



A more detailed account of the Permian of northern and northwestern 

 Arizona appears in Gregory's description of the Navajo Country.^ He 

 says on page 23 : 



"In mapping the geology of the Navajo country it was found that strata of 

 Permian (?) age are more widely extended than had previously been supposed. 

 They occur not only in the Little Colorado Valley, but along the San Juan and 

 at a number of localities on Defiance Plateau. In the western part of the reserva- 

 tion they mark the beginning of the red beds and are easily distinguished as a 

 whole from the underlying Kaibab by abrupt changes in color and in composition." 



On page 24 is given a "section of Moenkopi formation in the wall of 

 Little Colorado Canyon, about 5 miles below Tanner Crossing, Arizona," 

 as follows: 



Shinarump conglomerate; gray and mottled, cross-bedded; pebbles of quartz, quartzite, calcareous 



shale, and petrified wood. 

 Unconformity; marked by sudden transition of shale to conglomerate and by wavy, irregular con- 

 tact, including pockets in shale filled by sandstone and conglomerate. 

 I. Shale, red; bleached white at top, arenaceous and argillaceous, compact, hard, of microscopic 



fineness; weathers into rounded disks 3 



. Shale, red-brown and gray banded, argillaceous, lenticular, with lenses of sandstone at bottom ... 25 



2 



1 Darton, N. H., A Reconnaissance of Parts of Northwestern New Mexico and Northern 



Arizona, U. S. Geological Survey Bull. 435, 1910. 



2 Gregory, H. E., Geology of the Navajo Country, U. S. Geological Survey, Professional 



Paper No. 93, 1917. 



