Page:The Eurypterida of New York Volume 1.pdf/331



The Richmond group of Ohio, Indiana and Kentucky includes, in descending order, the following divisions:

In Ohio, most of Indiana, and a part of northeastern Kentucky, the base of the Liberty bed is formed by a stratum in which the brachiopod  is very abundant. This stratum is overlain by one in which  abounds, and at a still higher elevation   makes its first appearance.

The top of the Liberty bed is the horizon at which,  , and several species of Cyrtoceras occur. Immediately below these cephalopoda, or associated in the same layers, a large form of  is abundant.

The Liberty beds contain an interesting fauna. ,,  , and various crinoids occur here including   and. The Liberty beds were a favorite collecting horizon for the crinoid hunters 40 years ago. It was while working out a pocket in which  and   were abundant, that   was found. The locality occurs in the eastern edge of Warren county, Ohio. The road from Clarksville to Fort Ancient crosses Todds Fork half a mile west of Clarksville. A short distance beyond the point at which the road to Morrow turns off, on the left, is the home of Adam Pennington. The Megalograptus specimens were found about 100 yards directly west of the house, along a small stream. A wave-marked layer of limestone, 6 inches thick, overlies a few layers of limestone containing. Farther down stream there are no exposures for about 25 feet, but it is evident from the stratigraphy worked out in the surrounding country, that the wave-marked layer here mentioned belongs about 15 feet above the  horizon. The Megalograptus occurred in a series of crinoid-bearing clays, 3 feet above the wavemarked limestone.