Ulrich on Correlation of the Lower Silurian. 103 
The lowest rocks of this series are exposed in the gorge of 
the Kentucky river near Camp Nelson. From this point, 
which is at the summit of what the Kentucky geologists have 
called the "•Kentuck}- anticlinal," all the superposed strata dip 
rapidly to the south-east, and more slowly to the north-west, 
while in a due northerly direction, a very gentle dip, averaging 
nearly six feet to the mile, prevails far into south-eastern Ohio. 
Fine natural sections of the lower rock are presented in the 
almost vertical cliffs that border the Kentucky river along its 
course between Jessamine and Woodford counties on the north, 
and Mercer, Garrard and Anderson counties on the south. To 
the north and south of the river the topograph v of the country 
gradually rises, bringing to the surface the succeeding layers of 
the series. On the southern side of the river, the rate at which 
they are brought up is moderately rapid for the first four miles, 
along the Cincinnati Southern R. R., sloM^er for the next three 
miles, and scarcely appi-eciable duringthe following six or seven 
miles. At this point, which is situated a short distance south of 
Danville, the summit of the Kentucky anticlinal crosses the line 
of the R. R. in a north-east and south-westerly direction. A 
fault in this region brings up the sixth member of the series, 
which had already been passed at a point three and a half miles 
south of High Bridge. The dip of the rocks beyond the sum- 
mit of the anticlinal, which in this region has a more easterly 
and w^esterly direction than usual, is rapid, causing the rest of 
the Lower Silurian strata, here about yoo feet in thickness, to 
pass under the overlying Corniferous limestones and black 
shales at a point near McKinney's station, twenty-nine miles 
south of High Bridge. Between Danville and McKinney's 
station small patches of black shales are frequent, but I have 
not met with any exposure of Lower Silurian strata south of 
the last locality named. 
To the north from the river the country rises at first more 
rapidly than on the southern side, but beyond Nicholasville the 
strata are nearly parallel with the surface as far as Georgetown, 
thirty-three miles north of the river at High Bridge. From 
Georgetown to Roger's Gap, slightly higher strata make their 
appearance in the railroad cuts. At the last locality a large cut 
exposes the dark drab shales and thin, sandy lavers of lime- 
stone, which do not again come to the surface until we reach 
