1875.] OifO [Stevenson. 



Dr. Briggs' statement can be accounted for only by supposing that the 

 EUenboro' fault disappears long before reaching the Ohio, and that the 

 oil-brealc itself flattens out rapidly, so as to become a low anticlinal near 

 the river, over vphich the upper groups may pass unbroken. Still this 

 does not wrholly remove the difficulty. What the conditions may be 

 above Marietta, along the river, I do not know, never having examined 

 that region ; but I do know that rocks belonging to the Lower Barren 

 Group are found near Valley Mills, in Wood county, three miles from the 

 river and seven miles northeast from Parkersburg. In that vicinity, I 

 was unable to discover any rocks belonging to the upper groups. 



The oil-break passes through Wirt, Ritchie and Pleasants counties. 

 Beginning at the south, let us see the structure in the vicinity of the 

 Staunton pike, which runs along Hughes' River. The section of the west 

 slope is very prettily exposed on Fox's Run, about one mile north from 

 the Staunton pike, where we find : 



1. Red shales not measured. 



2. Shaly sandstone 20 ft. 



3. Red shales 105 ft. 



4. Shaly sandstone 30 ft. 



5. Red shales 50-60 ft. 



6. Sandstone, shaly to massive 65 ft. 



7. Chert 5-12 ft. 



No. 1 is not far from one hundred feet thick, and on it rests the massive 

 sandstone already mentioned as seen along the pike west from the 

 "break." Nos. 4, 5, 6 and 7 are wholly involved in the abrupt side, and 

 No. 3, partially so. The sandstones are all of a dull red color, and in 

 the wells bored just outside of the break, the whole mass was recorded 

 as red shale. On the east side of the break the exposure is yet more 

 satisfactory, as the road passes along the river bank, so low down as to 

 exhibit the flexure in the flint where the dip abruptly decreases from 35^^ 

 to 3°. The sandstones and shales of the preceding section are seen in 

 the hill above the flint, thus proving indisputably that the rocks on 

 each side of the "break " belong to the same horizon. 



There is no evidence of faulting on either side. The succession from 

 the inner portion of the abruptly tilted strata outward to the horizontal 

 strata is unbroken and pei'fectly clear. 



Within the break the rocks are almost horizontal and not much broken. 

 They describe a flattened anticlinal, for beginning inside and proceeding 

 outwards, say on the west side we find the dip first horizontal, then 2° or 3^, 

 then 28°, then 56°, then 3° or 5°, and finally outside almost horizontal. 

 A. similar condition is found on the eastern edge. Along the line of 

 section the chert is the last to show the abrupt dip. 



If now we ascend the hill from Fox's Run and go east about one-third 

 of a mile we find near Mr. Sharpnack's steam-mill, the sandstone and 



