BROWN AND YELLOW LOAM OF NORTH MLSSISSIPPI 297 



The Brown Loam and its substratum in many places in this 

 vicinity show a remarkable similarity to the Columbia formation 

 of McGee as described at its type locality. Yet the facts recited 

 above suggest that perhaps the Pleistocene history of the lower 

 Mississippi may not be so simple as he has pictured it. But it 

 is important to note, in this connection, that evidence of a distinct 

 episode between the Lafayette and the Brown Loam is confined 

 to the more inland and higher counties, such as Marshall and 

 Lafayette. Further west such a deposit, if it ever existed, has 

 been removed, and here, too, the Lafayette if it were ever thick 

 has been almost entirely removed, leaving only a few feet of 

 gravel and sand between the Loess and the Lignitic beds, as is the 

 case at Askew's Bluff, Panola county. In the bluff at Vicks- 

 burg, too, in some places, only a few feet of such gravel inter- 

 vene between the Loess and the Vicksburg limestone of the 

 Tertiary. 



Relation of the gravel deposits of north Mississippi to the Loess- 

 Loam. — These gravels, in the main, are considered as primarily 

 belonging to the Lafayette, but in many places they seem to 

 have been worked over and redeposited in the Loess-Loam, or at 

 its base, near their original location. The difference in the 

 stratigraphic position of the pebbles of the eastern and western 

 belts has already been noticed. In the former region, most, 

 if not all, the pebbles have been worked over. These also con- 

 tain a much higher percentage of chert pebbles — sometimes 

 quite large and angular, or subangular — derived from adjacent 

 Sub-Carbonifereous chert deposits. 



The gravels of the western belt are found most. frequently at 

 the base of the Loam or Loess. Generally it is not practicable 

 to determine whether they belong to the Loam (or Loess), or 

 whether to the top of the Lafayette. But occasionally a few 

 feet of Lafayette sand intervenes between the gravel bed and 

 the surface formation. At the Memphis bluff, as we have seen, 

 the gravels belong undoubtedly to the Lafayette. At a point 

 eleven miles from Batesville, on the Batesville and Water Valley 

 road, the following relations were observed : A hill mantled 



