284 T. O. MABRY 



An excellent illustration of the first is found in an exposure 

 of some thirty or thirty-five feet, four and one-half miles south 

 of Chulahoma, Marshall county, Mississippi. Here we find sev- 

 eral feet of compactly bedded pipe clay, with a billowy upper 

 surface, covered by eight or ten feet of Yellow Loam — from 

 which it is quite sharply separated — and resting upon a decidedly 

 eroded surface of cross laminated Lafayette sand. The three 

 formations are distinctly traceable for perhaps a hundred yards, 

 when the surface of the Lafayette descends so far as to be no 

 longer exposed. Stratigraphically and lithologically the three 

 formations are here very distinct, and show no evidence what- 

 ever of grading into one another. The erosion line between the 

 clay and the sand is as sharply defined as that between the clay 

 and the Yellow Loam. This clay, moreover, gives evidence, in 

 its irregular streakings of ferric oxide, of having once been highly 

 fossiliferous, and this evidence is strengthened by the fact that 

 it still contains a few leaves in a fine state of preservation. 

 These fossils were evidently formed i?i situ and not plucked from 

 older formations and redeposited. Not enough were found to 

 be of any practical value in determining the geological age of 

 the clay stratum in which they occur, and those found have not 

 been identified. Of the specimens in my collection at least two 

 distinct species are represented, the one having a very small 

 netted veined, linear-oblong leaf, resembling a willow leaf, or 

 the leaf of a water oak, the other also netted veined, oblong- 

 ovate, and entire, but much larger than the first, being about an 

 inch broad by two and a half inches in length. If the formation 

 in question belongs to the Lafayette, then the. Lafayette here 

 CDntains fossils of its own in its upper part; but it appears to 

 belong to a distinct epoch or episode, and the presence of fos- 

 sils in clay would seem to indicate conditions of deposition dif- 

 ferent from those which appear to have obtained when the 

 Lafayette sand, directly underneath, was being deposited. 



The accompanying photographs represent a continuous sec- 

 tion one-third of a mile north of the depot at Oxford, Missis- 

 sippi. A cut in the Illinois Central Railroad at this place, giv- 



