332 DESCRIPTIVE GEOLOGY. 



the Cretaceous. From Silver Creek, in the region of Wanship, all the way 

 to Kamas Prairie, the upturned Cretaceous and Jurassic strata on the west 

 side of the "Weber Valley are overlaid by the trachyte-flows. These tra- 

 chyte-flows cross the Weber just below Kamas Prairie, and overlie the 

 Cretaceous on the east side of the river in the angle made by its great - 

 bend. Just above the town of Peoria, the red sandstones of the Triassic 

 and the overlying Jurassic are exposed, striking a little north of east, and 

 dipping at a high angle, usually about 50° to 60° to the northward. The 

 Triassic is here exposed for about 700 or 800 feet, the lower beds showing 

 some white sandstone, while in the upper portion the characteristic cross- 

 bedding, identical in appearance with that at the quarry in the Lower 

 Weber Canon, is seen. These are overlaid by a fine gray lithographic 

 limestone, breaking into rectangular fragments, intercalated with yellow 

 earthy marls, not unlike those of the Lower Cretaceous, but containing 

 numerous well-defined Jurassic fossils, among which were recognized Eumi- 

 crotis curta and Pentacrinus asteriscus. Above these marls and sandstones are 

 a series of variegated shales, all conformable, and gradually lessening their 

 steep dip, until they pass into soft calcareous sandstones and mauve-colored 

 shales, which are immediately and conformably overlaid by the conglom- 

 erates of the Dakota Cretaceous. These are about 150 to 200 feet thick, 

 and enclose pebbles the size of a cobble-stone. They are again overlaid 

 by a series of yellow sandstones and about 1,000 feet of intercalated soft 

 clay-rocks and dark shales. The dip at the upper part of these shales 

 lessens to about 25°, which inclination is kept for a mile down the canon, 

 the series being made up of alternating beds of cream-colored and green 

 sandstones, separated by passages of shales and inconspicuous sheets of 

 conglomerate. In them, the remains of Fucoids are very frequent, and in 

 one or two shale beds a few fragments of Inoceramus are found. The whole 

 conformable northerly-dipping series of the Cretaceous cannot be less than 

 3,000 feet thick. 



Following the easterly strike of these Cretaceous rocks up into the hills 

 to the east, they seem to be overlaid, for a considerable distance, by the 

 trachytes, which extend northward in a narrow neck overlying the Tertiary 

 conglomerates. To the east of this neck is a triangular exposure of the Cre- 



