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



stratigraphic break also points in the same direction. The fossiliferons 

 beds at the base, however, contain only marine- and brackish-water 

 species, and unfortunately these do not furnish a good basis for correla- 

 tion with any zone in other Cretaceous sections. There is a great 

 abundance of fossils, but only a few species are represented and some 

 of these are forms that have great vertical range, while the others have 

 not been found outside of this district. The fauna as a whole has some 

 resemblance to that of the upper coal horizon (the "third ridge") at 

 Coalville, Utah, which, as will be shown farther on, is fully 1,800 feet 

 below the top of the marine Cretaceous there, but this resemblance can 

 not be accepted as proof of their contemporaneity. In Kanab valley 

 the marine forms were not found more than 100 feet above the base of 

 the sandstone, but in Long valley, only a few miles distant, they occur 

 100 feet higher. At the former locality fossil plants are abundant in 

 a band of sandstone 275 feet above the top of the fossiliferons marine 

 beds. 



The sandstones above the basal massive bed have about the same 

 character throughout. They are rather coarse, in a few instances 

 becoming pebbly conglomerates, and often so friable as to form soft 

 slopes that are easily mistaken for shale exposures. Many of these 

 sandstones are large lenticular masses rather than continuous beds 

 and nearly all of them vary greatly in thickness within short distances, 

 a peculiarity that often makes it difficult to recognize individual beds 

 in two neighboring exposures. 



From the above remarks it will be seen that both the Montana and 

 the Laramie formations are believed to be present above the Colorado, 

 but the lower limit of each of them is still undetermined. 



Before leaving the consideration of the Cretaceous in the high pla- 

 teaus of Utah the differences shown on the western escarpment at Cedar 

 city and Kanarra should be mentioned. At these places the equiva- 

 lent of the lower coal-bearing division of the Kanab section has a much 

 greater development and the other two divisions if present are con- 

 cealed by a sheet of eruptive rock. At both localities the lower 300 or 

 400 feet consist of gray and brown sandstones and sandy shales in 

 which no fossils were found excepting fragmentary remains of dicoty- 

 ledonous plants. Then comes a band of fossiliferous gray shale 30 feet 

 in thickness with a seam of coal at its base and a thicker coal bed 

 above it. The fossils are Ostrea soleniscus, Cardiumpauperculum, Bar- 



batia micronema, Corbula ncmatophora, Cyrena , Admetopsis rhom- 



boides, Eulimclla funicula, Ghemnitziaf and in some layers Unio. 



The coal bed immediately above varies in thickness from to 10 feet 

 at different openings. The overlying beds, of which about 350 feet 

 are exposed at Kanarra and fully twice that thickness at Cedar city, 

 consist of light gray and brown sandstones with some bands of shale. 

 Corbula nematophora, Ostrea soleniscus, and Admetopsis rhomboides 

 occur in great numbers at several horizons up to the top of the series. 



