An Account of the Middle Silurian Rocks of Ohio and Indiana. 



177 



with an occasional stromatoporoid fossil or cup coral, but practically 

 destitute of other fossils. According to Prof. Orton a valuable ledge 

 of Dayton limestone is found a few rods beyond in the fields. This 

 Dayton limestone is well exposed about half a mile west of the Thorp 

 farm, behind the house of Elizabeth Burnett, at the edge of the woods. 

 Here the weathered sides of the Dayton limestone courses often show 

 innumerable crinoid stems and beads, but of very small size, showing 

 the crinoidal character of this limestone, a fact also noted at the 

 Bigger quarry, on the Bellbrook pike, one-half mile S. of the U. P. 

 church, south of Beavertown. The same feature is also noted at the 

 John Kneisly farm mentioned on page 175. Fresh fractures do not 

 even show a trace of these crinoidal remains. The Clinton immedi- 

 ately underlies the Dayton limestone. The upper courses are not 

 exposed; only -fragments thrown up by a drain were seen. These 

 showed the presence of abundant Rhinopora verrucosa^ a few specimens 

 of LeptcBna rhomboidcdis, and a specimen of some species of Phcenopora . 



16. CentreviUe. — The quarry is about half a mile northeast of the 

 village, and a half mile northwest of the railroad station. The Clinton 

 here is well exposed, both the upper and lower contact being shown. 

 Under the Clinton occur about 30 inches of a firm, fairly hard, 

 greenish blue rock, evidently argillaceous. Layers are not so well 

 marked in it as usually so far to the west is the case in the Belfast 

 bed. The top of the Clinton limestone is wave-marked, the wave 

 ridges being north 55 to 65 west in direction. Over this wave- 

 marked layer occur 4 to 10 inches of the blue clayey or shaly Clinton, 

 so often found near the summit of the Clinton in Montgomery county. 



17. Huston's Quarry — three miles east of the Bigger quarry, the 

 latter being 5.5 miles southeast of Dayton on the Bellbrook pike, one- 

 half mile south of the U. P. Church. Huston's quarry lies in Green 

 county directly north of Bellbrook. Here the Dayton limestone is 

 well exposed. Much of it is of inferior quality. The uppermost 

 layer shows many small crinoid stems and some bryozoans, and 

 Heliolites. The Clinton beneath is reddish crinoidal ; its total thick- 

 ness is not exposed but can not exceed 4 feet in any event, since 

 the base of the Dayton limestone is only about 10 feet above the 

 base of the Belfast bed, and the brown shales of the Belfast bed are 

 known to have a thickness of six and a half feet. The Belfast bed 

 shales, in some of their courses, are hardly clayey, but rather firm, and 



