BR O WN A ND YELL OW LOAM OF NOR TH MISS1SSIPPL 299 



have been derived wholly or largely from the Loess-Loam, and 

 both formations being usually unstratified, we have no certain 

 means of discriminating the two. And, indeed, the necessity 

 for such discrimination seems very slight when we remember 

 that the formation of these stream terraces began immediately 

 after, or coincidently with, the general uprising which * brought 

 the Loess-Loam period to a close ; and that they are local lowland 

 deposits formed during a period of general elevation and ero- 

 sion, rather than general deposits formed during a period of 

 depression. The important point to remember is that the whole 

 of the area under discussion has never been under water since 

 the period of depression during which the Loess-Loam was 

 deposited, and that the interval of general erosion, and "loss of 

 record," which has existed here since the deposition of the 

 Loess-Loam is represented by the contemporaneous deposits of 

 lakes, streams, and adjacent shore lines. Geological history 

 written on tablets of ocean bottom is comparatively easy to 

 read, but written by lakes and rivers upon a scratched and 

 mutilated continental surface, it forms a palimpsest very difficult 

 to decipher by the aid of stratigraphy alone. As an evidence 

 of the truth of this statement I desire to call attention to the 

 different views prevailing among geologists as to the age of the 

 low level deposits known as the Port Hudson group. Some 

 consider this as the oldest of southern Pleistocene formations, 

 others believe that it corresponds to the last epoch of glacia- 

 tion. With this formation, however, the present paper does not 

 deal, since these deposits are not to be found within the area 

 under discussion. Loess has not been found, I believe, in the 

 North corresponding to the Drift of the third Glacial epoch, yet 

 it does not follow that the Mississippi did not continue to bring 

 down drift material during this time which may have been 

 added to previous deposits of loess or loam. 



Nor can we say that this process may not have continued 

 for some time after the final retreat of the ice beyond the Cana- 

 dian line. If we consider that the Glacial period began in the 

 United States when the land ice from Canada first crossed the 



