586 REPORT UNITED STATES GEOLOGICAL SURVEY. 



topography indicates that the strike curves to the westward, and con- 

 tinues the fold northward into the Preuss Range. 



Above the red sandstones is the following section, running eastward to 

 Thomas' Fork, the figures corresponding with those in the accompany- 

 ing plate: 



Sectio7i No. 29, from Bear Iiivej' eastward to Thomas' Fork. 



1. Red quartzitic sandstone, dip 70° to southeast. 



2. Laminated limestones. 



3. Blue limestones. 



4. Limestone shales. 



5. Blue limestones, ■with fragments of an indistinct ostrea, probably 0. strigulccula, 



dip 60° to southeast. 



6. Valley in which beds are concealed. 



7. Blue limestones dipping southeast rather steeply. 



8. Limestones like No. 7, almost vertical, but dipping northwest. There is some 



crushing of the beds here, but time did not permit close investigation of the 

 sharp fold. 



9. Covered space. 



10. Limestones dipping northwest about 45°. 



11. Valley covered with debris of limestones. 



12. Arenaceous and calcareous shales. 



13. Space with covered beds. 



14. Laminated blue limestones, dip northwest. 



15. Conglomerate with arenaceous matrix, containing rounded fragments of quartzite 



and limestone. This conglomerate rests horizontally and unconformably on the 

 limestones of layer No. 14. 



16. Covered space. 



17. Limestones. 



18. Space. 



19. Red sandstones. 



20. Valley of Thomas' Fork. 



21. Red sandstones, rising high on the slopes of the Sublette Range, standing almost 



vertical, dipping to the westward or northwest. 



The red sandstones of ISTo. 19 are probably the same as those of Sta- 

 tion b, and also those outcropping across the Bear, west of the station. 

 The station is on the sharp side of the anticlinal, the beds on the west 

 side dipping comparatively gently to the west. The distance between 

 this point and Station 100, which is also on lied Beds, seems too great for 

 the Red Beds of both points to be the same fold ; so that there is proba- 

 bly another fold which begins between the two points and continues 

 southward toward Station 108, which we have already described. 



From layer ISTo. 8 to the end of the section just given we find the lime- 

 stones, &c. (layers 10, 12, 14, 17, and 19), outcropping in low ridges so 

 obscurely that the angle of dip could not be determined. There is 

 scarcely any doubt of their Jurassic age, judging from the few fossils 

 seen and their position in relation to the Red Beds. As to the conglom- 

 erate, layer ISTo. 15, I am inclined to consider it of Pliocene age (the same 

 as similar beds in Bear Lake Valley, yet to be described), as they do not 

 resemble the Wahsatch beds on the plateau, which are also at a much 

 higher level. However, nothing was seen by us upon which any more 

 definite statement as to the age of the beds could be based. What was 

 seen was a mere fragment, but it indicated that this region has been 

 covered by a lake, and the probability is that the lake existed in late 

 Tertiary, or possibly in Quaternary time. 



The Bear Lake Plateau therefore consists of an irregularly-eroded sur- 

 face of the Wahsatch conglomerates and sandstones which rest upon 

 the upturned and eroded edges of Paleozoic rocks ; the latter for the 

 most part of Jurassic and Triassic (?) age. Toward the north the folds 

 observed in the uncovered portions of these beds show that before the 

 deposition of the Wahsatch Group the older rocks were subjected to 



