432 A. F. FOERSTE LIMESTONES OF TENNESSEE AND KENTUCKY 



far studies in this field have been chiefly of a paleontological nature. 

 The following notes are offered as a slight contribution to the subject : 



THE LEIPERS CREEK BED, TENNESSEE 



In the adjacent parts of Ohio, Indiana, and Kentucky the Richmond 

 group is about 300 feet thick. Southward it becomes rapidly thinner, 

 and was once believed to be entirely absent in central Tennessee.* 



In the summer of 1899, while investigating the Silurian rocks of Leipers 

 creek, in Maury county, Tennessee, the writer collected fossils from a 

 rock which appears so different, lithologically, from the ordinary Ordo- 

 vician rock of this region that it received special attention in a separate 

 paragraph in the Geology of Tennessee by Professor Safford.f 



" On Leipers creek, at the ' Oil Spring' (Tom Fox locality of this paper, 18), in 

 Maury county, and about half a mile below the Williamson line is another bed of 

 marble. This is a gray crinoidal, and coralline rock, spotted with red, and having 

 a flesh-colored appearance. Associated with it are other layers, with red, gray, 

 and green colors. Slabs cut from these rocks and polished present a handsome 

 appearance. The main bed is ten feet thick, and quite massive. This marble is 

 at the top of the Nashville formation, and is followed, in ascending order, by the 

 Niagara, which is here 50 feet thick ; and this, again, by Black shale, 8 feet, above 

 which is about 60 feet of the rocks of the silicious formation." 



This so-called marble bed is well exposed northward for about a quar- 

 ter of a mile, as far as the house of Carol Litton. Here it is seen to be 

 overlaid by thin Ordovician clay shale. 



The marble bed is also exposed at numerous points southward. It 

 occurs a short distance northeast of Elam's store, about half a mile from 

 Fly, forming the bed of the creek. It is here a salmon-brown rock, about 

 6 feet thick. It is overlaid by 1 foot of blue clay, 1 foot of limestone, 

 weathered into thin pieces at the top, and 4J feet of clayey material, all 

 containing Ordovician fossils. Immediately above is the base of the 

 Clinton, consisting of a white crinoidal limestone, with Atrypa nodostriata. 

 The bed is exposed north of R. S. Elam's house, a quarter of a mile north- 

 east of Fly. 



South of Fly the bed rises above the valley of the creek, and about 2i 

 miles south, north of J. M. Gardner's house, is found near the top of the 

 hill. The so-called marble la3'er is here crinoidal, richly fossil iferous, 

 and about 9 feet thick. It is overlaid by clayey beds, with Ordovician 

 fossils, and then by the conglomeratic layer at the base of the Black shale. 



The fossils collected from the so-called marble and from the overlying 

 clays were recognized by Mr E. 0. Ulrich as Richmond Group fossils, 



* Geology of Minnesota, vol. iii, part ii, 1897, section 9 in Introduction, 

 t Page 282. 



