64 



SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1921. 



forms. Here the tangential cross-l^edcling of 

 the upper white part is a striking feature and 

 resemlrlcs tliat of the Navajo sandstone farther 

 east. The thickness is comparahlo with that 

 at Zioii Canyon. 



The white npper part of the sandstone seems 

 to be the Wliite Chff sandstone, and the red 

 lower part the Vermilion Cliff sandstone of 

 Dutton and other earlier students of the geology 

 of the region. Huntington and Goldthwait ^' 

 called the red part the '' Kanab sandstone" and 

 the wiiite part the "Colob sandstone." As the 

 color boimdary within a short distance may 

 vary from the middle to the top of the Jurassic 

 sandstone, units based on color alone are hardly 

 tenable in this area. 



Lee •■'* found on Coal Creek, near Cedar City, 

 two raiissive sandstones separated by a softer 

 unit that aggregate 1,700 feet in thickness and 

 seem to represent our sandstone unit. Lee ^'' 

 later included about 400 feet more of lower 

 beds with these, but the character of the lower 

 beds fits the Chinle formation better, and they 

 should perhaps be assigned to that formation. 

 Lee considered the whole thiclaiess of 2,100 feet 

 to be the equivalent of the Wingate sandstone. 



Longwell *" found in the Muddy Mountains of 

 Nevada a cross-bedded sandstone ranging from 

 800 to 2,000 feet in thickness, resting upon the 

 Chinle formation. He correlated this unit with 

 the La Plata group. 



Whether this Jurassic sandstone of south- 

 western Utah and adjacent regions represents 

 the entire La Plata group of Gregory may be 

 questioned. It seems to be identical with Em- 

 ery's Wingate sandstone" of the San Rafael 

 Swell region and with the Wingate of Lee's Coal 

 Creek section. Dake ^- believes that it repre- 

 sents the entire La Plata group of Gregory, not 

 merely the typical Wingate, and disputes the 

 interpretation of Emery and Lee. 



The Wingate is reported to be unconform- 

 able on the Chinle formation at some places. 

 We saw no evidence of this unconformity in 



" Ilunlingtoii, Ellsworlh, and Goldthwait, .1. W., Ttic Hurricane (aillt 

 in the Toiiucrvilli; district, Utah: Harvard Coil. Mus. Conip. Zool. 

 Bull., vol. 42, p.2»:!, IH04. 



»» Lcc, W. T., The lion County coal hold, I'tali: V. S. C.col. Survey 

 Bull. 316, P.3IV2, 1W17. 



"' Lee, W. T., Karly Mesozoic physiography of the .soiilhern Roi-ky 

 Moiuitains: Smitli.sonian Misc. Coll., vol. CO, No. l, p. 22, lyls. 



" LonRvvcll, C. R., op. cit., p. ,51. 



" F.nicry, W. B., Green River Desert section: .\ni. .lour. Sci., Ithser., 

 vol. 10, pp. S.ll-.']??, 191S. 



«Dake. C. I,., The horizon of the marine .lurassic o( Ttah: Jour. Geol- 

 ogy, vol. 27, pp. (j:l4-G40, 1919 (l',)20). 



the ai'ea covered by our work, though close 

 examination was not made at many points. 



JURASSIC LIMESTONE AND SHALE. 



Resting on the thick Jurassic sandstone just 

 discussed lies a series of beds which consist of 

 red shale and sandstone, with some gypsum, 

 in the lower part and greenish-gray, cream- 

 colored, and brown marine fossiliferous lime- 

 stone in the upper part. The only section of 

 these beds obtained was measured on the east 

 side of Diamond Valley, 15 miles north of St. 

 George, Utah (section 21, p. 77). Here the red 

 shales and sandstone form the floor of the val- 

 ley between the sandstone and the limestone 

 and are but poorly exposed. Their total thick- 

 ness is about 160 feet. The patch of red rock 

 on the top of the West Temple of the Virgin 

 (Steamboat Mountaiii) seems to include this 

 interval but is a little thicker than the beds in 

 Diamond Valley. Above the red shales at 

 Diamond Valley is 300 feet of limestone with 

 some shale and gypsum layers, much of it 

 cream-colored, but some layers, especially in 

 the upper part, brownish, gray, and greenish 

 white. Fossils were observed in a number of 

 layers but were so poorly preserved as not to 

 be worth collecting- However, abundant Pen- 

 tacrintts stem joints, Trujonia sp. like T. ameri- 

 cana, and a small Ostrea were recognizable and 

 l\x the age as undoubtedly that of the marine 

 Jurassic of the region. 



Lee " measured near Cedar City 40 feet of 

 red shale and gypsum resting on the massive 

 Jurassic sandstone, then 250 feet of brown 

 earthy limestone which seems to correspond to 

 our beds. Stanton " measured near Glendale 

 a section with 8 feet of red shale neai- the 

 base, overlain by 292 feet of fossiliferous lime- 

 stone and shale. Dake *^ found near Teasdale 

 449 feet of gypsiferous limestone and shale 

 above his La Plata group. 



We saw no evidence of unconformity in this 

 series, but close examination was made at only 

 one locality. 



CRETACEOUS (?i VARIEGATED SHALE. 



Above the marine Jurassic limestone occurs 

 a bluish-gray, red, and greenish-gray "gumbo " 



Lee, W. T., The Iron County coalfield, Utah: U. S. Geol. Survey 

 Buil.316, p.3t)2, 1907. 



'* Stanton, T. W., unpublished notes. 



*' Dake, C. L., The horizon of the marine Jurassic of liah: Jour. 

 Geology, vol. 27, pp. 6:il-646, 1919 [1920]. 



