SEDIMENTARY BEDS OF THE WASATCH PLATEAU. 



165 



than those of the East Gunnison fault. Its position and relations are shown 

 in the stereogram and in the sections above referred to. 



Between the East and West Gunnison faults is an uplift, qualifiedly 

 tabular in form, which may be called the San Pete Plateau. Its northern 

 end is separated from the base of Mount Nebo only by a canon, which 

 emerges near the town of Nephi. Eastward it looks down upon San Pete 

 Valley, westward upon Juab Valley, which may be regarded as the noith- 

 ern continuation of Sevier Valley. Southward the plateau slopes slowly 

 as far as the town of Gunnison, where it becomes the floor of the Sevier 

 Valley. Its altitude is insufficient to warrant its admission as a member 

 of the group of High Plateaus. Its general form may be illustrated as 

 follows : If from a point situated about six miles south of Gunnison we 

 travel north 30° east, our course would lead us up into San Pete Valley; 

 if we travel north 30° west, it would lead us down the Juab Valley; if we 

 travel due north, we shall ascend the easy slope of the plateau to its sum- 

 mit at its northern end. Its transverse structure is shown in the sections. 

 Plate 6; sections 1, 2, and 3. 



SEDIMENTAKY BEDS COMPOSING THE WASATCH PLATEAU. 



The Wasatch Plateau consists of beds of Upper Cretaceous and early 

 Tertiary age, the latter being coirelated, as well as any lacustrine beds of 

 the Rocky Mountain region can be, with the Lower Eocene. In the low- 

 lands immediately adjoining are found, on the east the Lower Cretaceous, 

 and on the west a singular occurrence of the Upper Jurassic. There is 

 found also in the Sevier and San Pete Valleys, and in the low uplift between 

 them, a series of strata of later age than the Tertiaries of the plateau, 

 though from many considerations it appears that their age is with great 

 probability early Tertiary and immediately subsequent to that of the strata 

 upon which they rest. They are believed to be local deposits only, and to 

 have accumulated here and there after the commencement of the general 

 disturbance and uplifting which resulted in the drainage of the gx-eat 

 Eocene lake. 



The principal Tertiary series is provisionally divided into two ; the 

 lower can be referred with confidence to the same horizons as those occu- 



