t 
Ulrick on Correlation of the Lower Silurian. 105 
;»bout 350 feet in the gorge of the Kentucky river near the 
mouth of Cooper's branch. Following the outcrop in a south- 
easterly direction up the river, it will be found to dijD rapidly, 
passing out of sight within three and a half miles. Going down 
the river the dip is much less abrupt, the top being nearly 200 
feet above the water at High Bridge, and not reaching the 
water's level until near Tyrone in Anderson county. 
These rocks are usually fine-grained, hard and tough, and 
generally of a dark drab or dove color. Some are slightly 
crystallized and grayish, and many have a faintly mottled ap- 
pearance. Almost throughout they are heavy bedded, some 
of the layers being twenty feet or more in thickness, but the 
majority vary between one and two feet. Fossils are few, yet 
at several horizons there are a few thin layers with shaly part- 
ings, that are largely made up of organic remains. Such a 
horizon w\as noticed near High Bridge at about 150 feet below 
the top layer. Here the following sj^ecies were collected: 
Oft his subequata Conrad. Dabiianites sp. 
The shell n^va^A Atrypa dtihia, by W. Bathyurus (two species.) 
Maclurea magna Hall. Leperditia ca/iade/isis jone>i. 
Raphistoma pianist riat a ^ w-A-WparvaW. I^epcvditia!' tumida n. sp. 
■Orthoceras cxplorator Billings. Bcyrickia ? biciirvata n. sp. 
■Orthoceras furliviim Billings. Beyrichia pcrscidpta n. sp. 
Pterotheca {pi small species.) Stictopora fvncstrata Hall. 
■Cvpricardites sp. Mitoclcma cinctosinn Ulrich. 
^Conchicolites (a \'erv small species.) Several undet. species of Bryozoa. 
Some of the .species wxre abundant, particularly the Ostracoda. 
Between the top layers and sixty-five feet below there are 
■several intermittent horizons that have furnished a few fossils. 
Here Strophoiuoia incrassata Hall, RJiynchoiicUa plena Hall, 
Orthis costalis Hall, and jMaclurea magiia^ are sometimes nu- 
merously represented, while an occasional specimen of Asaphus ? 
margiiialis Hall, may be found. 
Beds H. This is a regularly bedded, dolomitic limestone, 
about ten feet in thickness, of a gray color, with greenish, blu- 
ish, or brown blotches. The whole, when weathered, assumes 
a color approaching buff. These rocks have received the siame 
*' Kentucky marble." Being unfossiliferous their principal in- 
terest, in this connection, consists in the fact that they are very 
persistent both in their thickness and lithological characters, hav- 
ing been met with in deep well-borings as far north as Cincinnati. 
