34 COLORADO FORMATION AND ITS INVERTEBRATE FAUNA, [bull. 106. 



UTAH. 



A portion of the Cretaceous in Utah has already been incidentally 

 described, but two other areas in that territory require separate treat- 

 ment oil account of differences in both lithologic and paleontologic char- 

 acteristics. One is the neighborhood of Coalville, in northern Utah, 

 and in connection with it certain small areas in southwestern Wyoming 

 may be conveniently discussed. The other is an irregular belt extend- 

 ing across the high plateaus of southern Utah, just south of the escarp- 

 ment of the Pink cliffs. 



In the area last mentioned several sections have been described by 

 Messrs Gilbert 1 and Howell, 2 which show a tripartite division of the 

 Cretaceous like that in the San Juan area with which it is geographi- 

 cally connected, but here the lower division of sandstones carries the 

 principal coal beds, while the upper division has only thin seams. 

 Other differences worthy of note are the occurrence of many marine 

 fossils in the sandstones near the base of the Cretaceous and the more 

 varied fauna of the lower part of the shales. 



Some years ago Mr. C. D. Walcott measured a section in Kanab val- 

 ley and made a considerable collection of Cretaceous fossils there. He 

 has generously placed in my hands his unpublished notes on theMeso- 

 zoic portion of this section, and the description given below is based on 

 these notes, supplemented by my own observations made during the 

 summer of 1892, Avhile studying the same section and a neighboring one 

 in Long valley. The measurements are all Mr. Walcott' s, but the de- 

 tailed subdivisions are not given. 



Cretaceous section of Upper Kanab valley. 



Feet. 



1. Alternating beds of light- colored sandstones, clay shales, arenaceous shales, 



and coal, the sandstones constituting about one half of the entire thick- 

 ness. At the base is a thin, irregular band of conglomerate and coarse 

 sandstone resting on softer sandstones and shales that are provisionally 

 referred to the Jurassic. Leaves and other plant remains occur about the 

 middle of the division, and two zones near the top contain numbers of Cor- 

 bula nematophora, Cardium paupeiculum, Modiola multilinigera, Glauconia 

 coalvillcnsis, a small Ostrea and an A nomia. Thickness 330 



2. Arenaceous and clay shales, mostly of a drab color weathering into rounded 



hills and slopes of soft, more or less sandy clay. Near the base the shales 

 are slightly bituminous and contain many limestone concretions, some 

 of which arc filled with well preserved fossils. (See list below.) Thickness. 685 



3. Bather coarse friable sandstones of light colors (white, gray, and buff), 



alternating with thinner beds of gray, drab, and purplish arenaceous 

 shales. The lower 50 feet is a massive yellow or buff sandstone, which is 

 overlain by 50 to 60 feet of softer very fossiliferous sandstones, containing 

 great numbers of Ostrea soleniscus, Admetopsis (an undescribed species), 

 Modiola multilinigera?, Cyrena, Anomia, and a few others, while the upper 

 portion contains plantremains with Unio holmesianus, Viviparuspanquitchen- 

 s\8, Planorbis Physa, etc., that seem to belong to the Laramie. Thickness . . 1, 700 



i Op. cit., pp. 158-160. 



2 Ibid, pp. 270-280. Dutton's "Geology of the High Plateaus of Utah " and "Tertiary History of the 

 Grand Canon District" contain good general descriptions of the stratigraphy. 



