Cincinnati Society of Natural History. 



2 to 3 inches thick. This stone corresponds to the upper harder 

 rock at the High Banks between Tippecanoe and Troy, but is 

 apparently less firm. Below it are 5 feet or more of a blue shale, 

 more clayey and more soft than that above, and in thinner courses. 

 These softer rocks are readily loosened by the combined effects of 

 moisture, weathering and frost, and by receding have caused the falls. 

 The upper firmer layers decrease in thickness towards the south side 

 of the falls. If they represent the Belfast bed of more eastern sections 

 as is believed to be the case, they certainly have changed consider- 

 ably from the typical form of the rock. 



25. West Milton — on the Stillwater river, 15 miles northwest of 

 Dayton. The Clinton is here well exposed along the road leading 

 down Irom the main street eastward to the river bridge. On the west 

 side of the river, immediately facing the bridge, is a steep cut made 

 by a rapidly descending streamlet. At its top the Clinton is again 

 well exposed. Underneath it are 58 inches of a blue shaly clay. 

 Then, 8 inches of a hardened blue clay in a single layer, similar to 

 some of the rocks called the Belfast bed in more eastern regions, for 

 example at Goe's station. Beneath this are 62 inches of blue shaly 

 clay, in the lower 2 feet of which were found specimens of Of this 

 biforata, the Lower Silurian forms with fairly broad plications. Then 

 in descending order: 14 inches of blue clayey shale, 12 inches of 

 a hardened shale or clayey limestone, 16 inches of a hardened rock, 

 which breaks up in shaly pieces, 9 inches of a hard blue rock, a 3 inch 

 course of similar material, 13 inches of blue shale, and 9 inches of poor 

 clayev limestone with Tetradium and Orthis occidental is Next, 9 inches 

 of soft blue clayey shale, cut back by the streamlet, a 9 inch slope of 

 hardened shale, 6 inches of soft limestone breaking up into shaly 

 fragments, 12 inches of blue shale, rather soft, with Orthis occidentalis, 

 Otihis bifomta, Orthoceras, and Lower Silurian bryozoa. Then come 

 harder courses, first as a 16 inch slope, then in 4, 6, and 8 inch 

 layers, then 8 inches of a shale, between blue and brown in color, 

 forming with the 8 inch hard layer just above a vertical face. This 

 hard layer had on its upper side the appearance of having been gouged 

 out by a tool about a tenth of an inch wide, the sides of the cavities 

 being straight, the length an inch or less, the depth hardly more than 

 a quarter of an inch, and the bottom a regular concave curve. Similar 

 markings were seen in the Lower Silurian rocks of a bridge pier in 

 Clinton county, northeast of Spring Hill several miles. Below the 



