172 The American Geologist. ■ March, 1891 
"Whence, having solved with respect to dip, — 
Dip of Corniferous lhnestone=43 feet per mile, south, 17° E. 
Likewise by taking the localities and altitudes of the Pope Hollow 
conglomerate as given in the preceding pages, its dip will be found 
to be 23-feet per mile, south 18° or 19° west. 
The difference in direction and amount of dip in these two for- 
mations is, accordingly, very marked ; } r et it can be readily ex- 
plained : While the effects of the Cincinnati uplift are so felt in 
this region as to give the dip of the Corniferous limestone a moder- 
ate eastern deflection from true meridian, the thickening towards 
the south and the thinning towards the west of the superincumbent 
formations is such as to render the dip in the Pope Hollow con- 
glomerate far less than that of the Corniferous limestone, and to 
give it a strong western deflection.* 
That these formations thin out rapidly going westward, is a fact 
too well known to require any special comment here ; the ' ' thick- 
ening towards the south," can be demonstrated as follows : 
Altitude of horizon "C" at "B" (See plate v.) about 1150ft. A. T. 
" " " Jamestown well 375 ft. A. T. 
Difference in altitude 775 ft. 
Distance between "B" and Jamestown 2734 mis. 
.*. Rate of dip along this line 28-fft.per ml. 
Dip of Pope Hollow conglomerate in same direction. . 23 ft. per ml. 
Hence the thickening of that portion of the Chemung group 
which lies beneath the Pope Hollow conglomerate, at a rate of 5 
ft. per mile. 
Again, Alt. of horizon "b" at "C" 573 ft. A. T. 
" " " Jamestown well -940 ft. A. T. 
Difference in altitude 1513 ft. 
Distance from "C" to Jamestown 44 miles. 
Hence, rate of dip of lower surface of Portage group =34. 4 ft, 
per mile, or about 6. 4 ft. more than that of the upper surface. 
Finally, Alt. of Corniferous limestone at Black Rock 625 ft. A. T.f 
" " " " Jamestown. ... -1450 ft. A. T. 
Difference in altitude 2075 ft. 
Distance between Black Bock and Jamestown 59.3 mis. 
*A similar difference in rate of dip of the Corniferous limestone and 
upper Chemung, or lower Coal Measures, lias been noted by Prof. H. S. 
Williams along his Genesee section. . Bull. U. S. Geol. Surv., No. 41, 
pp. 103-104. 
fC. A. Ashburner: "Petroleum and Natural Gas in the state of New 
York." Trans. Amer. Ins. Min. Eng., Vol. xvi, 1888, p. 921. 
