GEOLOGICAL SUEVEY OF THE TEKKITOEIES. 531 



degree in the dip, and the total average thickness, though greater, per- 

 hapSj than that we have given in our estimates in the detailed section, 

 is hardly as much as would be indicated by the angle of the dip at 

 numerous points where it was taken. 



Hallville. — The horizon of the 'Hallville coal is included in this 

 section, though the mines themselves are at least one and a half miles 

 distant from any part of the line, and are separated from it by the bot- 

 tom-lands of Bitter Creek. The coal itself could not be recognized, and 

 perhaps is only represented by some of the carbonaceous seams noticed 

 between Nos. 8 and 20. The surface indications, however, are possibly 

 deceptive, and excavations would, perhaps, discover the coal as fully 

 developed as at that place. We visited Hallville, and made a rapid 

 examination of the surroundings. The mines had not been worked for 

 a considerable period, and the place was entirely abandoned at the time 

 of our visit. The drifts had partially fallen in, and we were unable to 

 procure any fossils from the roof-shales, &c., of the coal ; for the same 

 reasons, we could not get a very good section of the mines. We no- 

 ticed, however, a considerable local disturbance, including an apparent 

 southwesterly dip, at one of the points visited. I have already men- 

 tioned this disturbance in speaking of that noticed at the junction of 

 sections 2 and 3 5 it seems to be altogether local, and certainly does not 

 extend to the corresponding beds on the other side of Bitter Creek. 

 That noticed in No. 1 of the foregoing section, although in a higher geo- 

 logical position, may, as has been suggested, be due to the same cause, 

 and simultaneous. In passing eastward from Hallville toward Black 

 Buttes Station, we observed at a point considerably higher in the series 

 a development of some 40 feet or more of whitish sandstone and sandy 

 shale, which could be continued by the eye in the direction of the strike 

 across the line of the section, in which it is represented mainly by ISTo. 

 5, and perhaps partially by the beds immediately below. This band of 

 whitish sandstone and shale, though varying in width as it was traced 

 by the eye, formed about the best and most continuous horizon in the 

 section. In several cases one of the lignite seams had taken fire along 

 its outcrop, and could be traced for a considerable distance by the baked 

 and reddened clays immediately above it ; but these were not generally 

 so continuous over so long a distance, nor were they so valuable in 

 determining the relative position of the Hallville beds in the series. 

 For the most part, the remarks as to the variability of the characters of 

 the rocks which were made in reference to the Black Buttes section 

 will apply equally well here. The fossils found, with the exception of 

 some leaves of dicotyledonous plants in some of the upper sandstones, 

 and apparently the same as those noticed in the beds of the Black Buttes 

 section, were all from beds Nos. 9 and 12, and consisted of only one or 

 two species of oyster. The soft, sandy shale of No. 9 was in places al- 

 most displaced by these shells, which made up, I should judge, nearly 

 or quite one-half of the mass of the stratum. 



Passing west from Hallville, the heavy sandstone No. 32 forms high, 

 nearly perpendicular blufi's on the right of the railroad, which here 

 seems to run nearly along the strike of the great fold across which these 

 sections are taken. The cliffs continue to border the railroad to Point 

 of Eocks Station, where they open somewhat, and a higher series of 

 beds come in view ; beyond this place they again close in and continue 

 near the track for the distance of a mile and a half or more. The whole 

 thickness of the beds is much greater than is given in the section, in 

 which only their upper portion is included ; I have roughly estimated 

 it as much as 500 feet. For the most part the bluffs consist of a coarse. 



