SEDIMENTARY BEDS OF THE WASATCH PLATEAU. 167 



Series No. 2 (Tertiary), section No. 7 B : Feet, 



(a) Cream and gray limestone, containing a few fish-scales; bed of chert at top . . 300 



(6) Greenish calcareous shale 300 



(c) Pale red marly shale 300 



900 



These beds are assigned provisionally to the Lowei' Green River epoch. 

 Unlike the series below them, they cannot be directly connected with the 

 strata lying at the base of the Uintas, nor are their fossils a satisfactory 

 guide to a decisive correlation, though the presence of fishes resembling 

 those of the Green River beds might be regarded as indicating such a rela- 

 tion. They have not, however, been identified as belonging to the same 

 species as those of the latter formations. The beds in question are found 

 only in the Sevier and San Pete Valleys, in the uplift between them, and 

 extending a short distance up the great monoclinal flanking the west side 

 of the Wasatch Plateau. That they formerly extended over that plateau, 

 and for an indefinite distance eastward, is very probable. In this portion 

 of Utah they are the last lingering remnants of a series which was nearly 

 and in many large areas quite the last to be deposited and the first to be 

 attacked by the general process of degradation which has swept away such 

 vast masses of strata. From the summit of the Wasatch Plateau this whole 

 group of beds has been eroded and about 300 feet of the Bitter Creek beds 

 immediately beneath, and this amount of denudation is probably the mini- 

 mum of the whole Southern Plateau Province, except where the sediment- 

 ary beds have been protected by volcanic rock or have enjoyed unin- 

 terrupted protection in gravel-covered valleys between great uplifts. 



The uppermost series of Tertiary beds has been alluded to as consist- 

 ing probably of a series of local deposits accumulated after the general 

 upward movement of the whole Plateau Province had commenced, though 

 it seems probable that this movement was then in its earlier stages. The 

 beds contain fossils very similar and perhaps in some cases identical witb 

 the species of Planorlis Physa Helix (?), and Vivijiarus, which are found in 

 the series upon which they rest. Lithologically they are much more 

 variable. Some of them are conglomerates, which are apparently of allu- 

 vial origin, and none of them are found to be continuous over a large area. 



