GEOLOGICAL SUEVEY OF THE TEREITOEIES. 525 



Adding to tliis several buudred feet of beds not well exposed, but which 

 must intervene between the westernmost ridge and the point where the 

 dip ceases and the strata become horizontal, we have, at a moderate 

 calculation, from 2,100 to 2,500 feet of these whitish clays and darker 

 shales and sandstones above the heavy-bedded sandstone in the bluff 

 which formed the lowest geological horizon in our hurried examination 

 at this point. We have no positive evidence as to the character of the 

 intermediate beds between the moi"e widely separated ridges, as the 

 wash from the elevations and surface-soil covered all the evidences of 

 stratification. An artesian boring at the station gives a record ol 

 alternations of clays, shales, and soft arenaceous beds for some 540 feet, 

 which is probably the usual character of the softer beds generally. 

 The greater part of this thickness is probably of Tertiary age ; the lower 

 portion, however, may belong to the upper part of the Cretaceous. 

 There are no positive evidences of any uuconformability, notwithstand- 

 ing the sudden lessening of the angle of the dip, and no recognizable 

 horizon of separation of the two formations in the whole series above 

 the heavy sandstone. 



Bitter Creek. — From Separation we passed on by railroad to Bitter 

 Creek, making no stoppage at intermediate stations. For the whole 

 distance there appeared to be only exposures of higher Tertiary beds, 

 mostly horizontal, or nearly so, which fill the trough between these sta- 

 tions. At Bitter Creek we stopped over one day and examined these 

 upper beds, as they are to be seen in the immediate ^iciuity of the sta- 

 tion and in the hill known under the name of Table Eock, some four 

 miles or more distant. 



Table Rock is a spur of the range of Tertiary hills v/hich appear for a 

 long distance on the southern side of the railroad, and also to some extent 

 in conical outlines to the northward. In its upper i)ortion it is itself an 

 outlier, the strata of which this part of the hill is comjiosed having been 

 washed away in its immediate vicinity. The section it afforded is as 

 follows, the beds numbered from above downward : 



Section of the beds exposed in Table Eoclc. 



Ft. lu. 



1. Hard brownish sandstone, largely made up of im- ") 



perfect casts of TInio, &c „......,„ 15 



2. Shale, partly carbonaceous 6 



3. Light-brownish sandstone, massive and incoherent-. 20 



4. Sandy shales, light-colored 3 i . 



5. Same as is^o. 3 12 f ^• 



6. Shaly sandstone, light-brown or buff 20 



7. Sandstone, same as >To. 3 , 12 



8. Light-colored shaly sandstone, with intercalated beds 



of clay and shale 240 j 



9. Harder and slightly darker colored sandstone, with 



a great abundance of fossils, &c., Melania, Vivipa- 



rus, &c., top of first bench 12 



10. Shaly beds 25 



11. Sandstone beds, containing Melania, Unio, &(i 10 



12. Shaly beds, with a few intercalated thin layers of I 



harder sandstone, and a four-foot seam of dark j 



shale, about midway from top to bottom 134 ^ 



From the summit of the rock we observed, five or six miles away to the 

 eastward, benches composed of beds superior in position to any in the 

 above section, the thickness of which I roughly estimated at 200 feet. 

 The thicknesses of the different members of the section itself are in a 



yB. 



