BR O WN A ND YELL OW LOA M OF NOR TH MISSISSIPPI 2 9 1 



therefore upon that of the Yellow Loam, is that furnished by the 

 character of fossil plants found in the bowlder bed at Oxford 

 previously described. The value of this evidence, however, is 

 diminished by the fact that it is not absolutely certain that they 

 came from the Lafayette formation. These fossils are mainly 

 leaves and small stems, and occasionally an acorn (?), of what 

 "seems to be a new and very fine species of Quercus " (Knowl- 

 ton); and sometimes there is found a specimen of a palm, that 

 "is with little doubt Flabellaria Florissanti, Lx, found origi- 

 nally in the Eocene of Colorado" (Knowlton). The pre- 

 serving agent is apparently red hematite which shows up the 

 smallest veinlets of the leaves. Indistinct traces of grass-like 

 plants are also to be found. In answer to inquiries as to the 

 probable age of these fossils, as referred to the accepted 

 geological time scale, and the probable climatic conditions then 

 prevailing, as indicated by the nature of the plants, Dr. Knowl- 

 ton has this to say: "The data upon which to base an opinion 

 of age is, as you see, quite too scant for a positive assertion. I 

 should say, however, that it indicated rather an Eo-Lignitic than 

 later age. Could it be possible that the clay in which the plants 

 occur was a pocket or lens which had been torn from the 

 Eo-Lignitic and redeposited in the Lafayette ? However, I 

 incline to the opinion that they are Eocene rather than later, 

 but more material will, be needed to confirm or disprove this .... 

 the above mentioned plants do not indicate any marked change 

 from the climate of the present day .... I imagine that when the 

 fossil flora is thoroughly studied we shall find that species or 

 forms have persisted for long periods of time with comparatively 

 little change." 



This paper deals with the study of the Lafayette formation 

 only to the extent necessary for fixing the lower limit of the 

 Yellow Loam. And the foregoing evidence of unconformity 

 between the two is adduced in corroboration of the evidence 

 presented by Chamberlin and Salisbury {Am. Jour. Sci. Vol. 

 XLI, p. 359 et seq.) in favor of the preglacial age of the Lafay- 

 ette. The proof of the glacial age of the Loess of the Missis- 



