1872.] 569 [Lesley. 
head of the Geology of the Wellsborough Valley or Tioga River District 
in Tioga County. To trace the thinning away of these calciferous and 
ferriferous red beds of VIII (Lower Divonian) on their way towards Ohio, 
underground, is one of the desiderata of American geology. 
Other well-boring records are published on pages 227 ff, vol. X, Proc. 
A. P. §., but most of them are confined to the Coal Measures. Those on 
p- 288 ff, however, penetrate the Deyvonians to considerable depths and 
show the red rocks in positions analogous to those described above. 
In one well, at the head-waters of the Clarion, the mouth of the well 
being 3870 feet below a coal bed, and also below the bottom of XII, the 
red rocks of IX (?) occur from 216 to 415 —an interval of 200 feet, 
which is abont the normal thickness of IX in this zone of its decresence 
westward, The Manchester (Tioga river) red beds (?) were struck at in- 
tervals from 925 to 956 = 41 feet, 7. ¢., with an interval of 510 between 
their top and the bottom of IX. 
In the Glade Well near Pithole (page 241, vol. X), in the Oil Creek 
country, the red slates were first struck at 196 and got through at 318, 
the interval being 122 feet. Some red shale was then struck near the 
well bottom (abandoned, no oil) at 612, 7. ¢., 294 feet below the bottom 
of the upper red shales. 
These also probably represent UX and the Manchester red beds, with a 
diminished interval due to westing. 
These red rocks correspond to the Marshall group of Michigan, of 
Winchell (Proc. A. P.8., vol. XI., p. 74), the Gritstone redrocks above 
and the Chocolate shales below (the latter just over the Hamilton) in 
Ohio (Idem, p. 75), and to the Brown shales of the Keokuk group of 
Indiana. They are very noticeable to the traveller on the railways cross- 
ing Northern Ohio. 
Norr.—l have received the following letter of explanation respecting 
the wells at Brady’s Bend : 
Sr. Lours, Mo., November 13, 1872. 
Dear Sir:—The detailed surveys were begun and mostly made under 
my direction, and the wells Nos. 6, 7, 8 and 9 were located by me. This 
would be of no interest to you or the public were it not that the location 
of these wells was the result of a long, carefully pursued, and at least 
apparently successful investigation into the laws of the distribution of 
the oil in the ‘‘sandrocks.’’ 
You had already shown that these rocks existed there and at what 
depth, and had also shown that the general stratography of the district 
rendered it reasonably certain that oil would be found there, and this had 
been confirmed by the results of boring in the case of two of the five wells 
sunk, 
I tried to find the law of distribution in its application to narrower 
limits, so as to decrease to the utmost the risks, and inerease to the 
utmost the chances in sinking wells. 
Of the five sunk before I went there, two were productive ; of the four 
sunk since I left, one is productive; of the four I located, namely, Nos. 
A. P. 8.—VOL. XII.—3T 
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