GEOLOGICAL SURVEY OF THE TERRITORIES. 533 



Feet. 



18. Grayish-drab massive sandstones 20 



19. Ash-colored clavs and sandy shales 13 



20. Whitisb-bufif sandstone 3 )>p. 



21. Light-colored sandy shales, with thin carbonaceous seams. 7 



22. Massive grayish-buft and whitish sandstone, with interca- 



lated light-colored sandy shales 132 



23. Carbonaceous shale ; tiace of coal 2 



24. Grayish and bluish while sandstone and sandj^ shale 25 



25. Carbonaceous shale 4 



26. Massive sandstone, bluish white above, grayish buff" be- 



low GO 



27. Light-gray shale and shaly sandstone 18 



28. Black shale and coal o-o 3 



29. Grayish-buff and bluish-white massive sandstones, some ) 



portions even weathering brown, with frequent iuterca- > Q. 



lations of soft sandy shales 200-300 ) 



The thicknesses of the different beds given above are, as in the other 

 sections, for the most part merely estimates, such as could be made by 

 walking over the upturned edges of the strata. I am of the opinion that, 

 taken as a whole, the thickness is rather under than over estimated. 

 The angle of the dip varied in different parts of the section : in the upper- 

 most beds, which were at the eastern extremity of the line and farthest 

 from the axis of the fold, the dip was from 5° to 8°, and from there it 

 decreased toward the westernmost and lowest exposures to from 2° or 

 3° to 5°. The direction was throughout about the same, nearly north- 

 east. The line followed commenced, as has been already stated, near 

 the railroad-track, two and one-half miles from Point of Eocks, and ended 

 at a i)oint some distance to the right of the railroad, and nearlj' four 

 miles, in a nearly due northeast direction, from Salt Wells Station. 



A few leaves were found in one or two of the sandstone layers, but 

 ■were not in any way characteristic, and the bed No. 4 was almost 

 entirely made up of fossils and their casts, chiefly of a species of Ano- 

 mia, together with oysters, Corhleula, Corbnla, and a few specimens of 

 Modiola and Goniobasis. 



With this last section is completed the whole series of variegated 

 sandstones and shales on the eastern side of this great fold or anticlinal, 

 which continues in the vicinity of the railroad from between Bitter 

 Creek and Black Buttes Stations nearly to Salt Wells. The total thick- 

 ness of this series, reckoning from a point east of Black Buttes to this 

 place, cannot be much less than 4,000 feet, though in our estimates in 

 the detailed sections we have rather fallen short of this total. This is 

 mainly due to our caution against making an overestimate, and the 

 nature of the exposures, which in many places only consisted of a very 

 gradual slope or shallow valley, showing by its debris and on the sur- 

 face the general character of the beds. The sections show the pecu- 

 liarity of the series, its alternations of light gray, grayish buff', and 

 whitish and brown sandstones, with drab and ash-colored shales and 

 clays. As regards, however, the alternations themselves, these sections 

 are for the most part correct only for the particular line on which they 

 were taken, the great majority of the sandstone beds changing in respect 

 to color, hardness, and stratitication even within the distance of a few 

 feet. I am of the opinion, moreover, that the coal-seams also share 

 this general character of variability, but our examinations could not be 

 sufficiently minute to determine to what extent this is the case. 



The accompanying wood-cut is intended as a general section of the 



