and Superior Formations of West Tennessee. 367 
The group must be of considerable thickness, not less than 
400 or 500 feet. It is mostly made up of stratified sands. Oc- 
casionally an interstratified bed of dark slaty clay, ten to thirty 
feet thick, is met with, but more frequently a sandy bed lamina- 
ted with clayey leaves. In its lithological character, the group 
ig much like the Coffee sand. Its sandy mass, as seen at the sur- 
face, is very generally yellow, brown or orange, its contents bein 
eroxydized ; occasionally, however, in partially protected or in 
resh exposures, its material is dark colored, abounding more or 
less in fragmentary lignitic matter. 
The outcrop of the group very commonly presents layers or 
masses of ferruginous sandstone locally indurated by oxy of 
iron. This sandstone often occurs in plates, scrolls, tubes and 
other curious shapes. At some points, especially upon high 
knobs and ridges, it is found in heavy massive locks from two 
or three to fifteen feet in thickness. The occurrence of such 
sandstone is, however, common to all the sand-formations of 
West Tennessee. In this group it appears to be especially 
abundant. 
branch of Cypress Creek, (of Hardeman,) and near the “old 
stage road.” Each point is indicated upon the map by a small 
Cross, 
_ The following is a list of species from the two beds, to which 
it will be seen quite a number of the forms are common. = Al 
of them are described in the Jour. Acad. Nat. Scv. of Phila., vol. 
iv, 2d series, The localities are (a.) limestone ; (b.) sand-bed. 
1, Corbula subcompressa, Gabb, - - 2 - b. 
2. Venus Ripleyana, Gabb, - - : - a, b. 
____On the ma ‘oe this article, Muddy Creek is the first stream rep- 
Tesented east of na onthe calico’. M. is Middleton depot. 
Dedicated to Prof. H. A. Gwyn, of Saulsbury, Tennessee. 
