F. B. Zoomis — Origin of the Wasatch Deposits. 361 



Certain general features should be especially noted : There 

 is a lack of sharp cleavage planes between the stratification 

 layers ; the sorting is irregular, so that the clays are a mixture 

 of variable sands and clays, and the sandstones partake of the 

 nature of gravels in that pebbles and grains of various sizes 

 occur; beds change their character or run out, making levels 

 hard to follow for considerable distances. These are all flood- 

 plain characteristics, the sorting in a lake being much more 

 uniform. 



On analyzing the section, it is noticeable that the upper part 

 is composed chiefly of brown and gray clays, the middle por- 

 tion has the red beds, while the basal portion tends to blackish 

 and dark shales. These colors are largely due to the content 

 of iron, which in the presence of considerable bituminous 

 material makes carbonates and gives the black and slate colors. 

 Where little vegetable matter is present, the hydrated oxid, 

 limonite, makes the sandstone and shales cream and brown in 

 color ; however, when exposed to air, if under dry and hot 

 conditions, the limonite is reduced to hematite, the color then 

 changing to red. 



With these points in mind, it would appear on consulting 

 the section that the lower sandstones were deposited rather 

 rapidly, the dark shales representing the alluvium spread over 

 a country covered with vegetation. This opinion is further 

 ■confirmed by finding in level 21, at the point marked x, a rich 

 bed of plant remains. Above this red beds soon begin to 

 appear, and are apparently due to the alluvial deposits being- 

 exposed to the sun, the vegetation cover being scantier and the 

 effect of the heat greater. Above level 12, red beds with 

 bands of sandstone predominate. In the Buffalo Basin, the 

 fossiliferous layer is just, below level 11, and very little was 

 found in any other horizon. On the opposite side of Tatman 

 Mountain, however, such layers are considerably lower, the 

 uppermost being a full 100 feet below the Buffalo Basin level 

 and the lower level 100 feet below the upper one. The 

 deposits on the north side of the mountain are more predomi- 

 natingly red. These red beds seem to have been exposed some 

 time to the air and presumably, in the natural course of events, 

 the bones of terrestrial animals were left on these flats and 

 were subsequently covered by an alluvial deposit ; at the same 

 time, occasional crocodiles, fishes, or turtles, becoming stranded 

 far from the river, mixed their remains with those of the land 

 forms. The coryphodons seem to have been amphibious, some- 

 what like the hippopotamus, and would be either in the stream 

 or would follow the flooded country. 



The uppermost 900 feet are non-fossil if erous, mostly clays 

 brown to greenish in color, as though not exposed to the com- 



