38 MISSISSIPPI STATE GEOLOGICAL SURVEY [Bull. 
further deseription will be embraced under discussion of the 
next region. 
North Central Plateau.—This region is much larger than 
any of those so far considered It cecupies all that region of 
the northern half of the state lying west of the Flatwoods and 
east of a belt fifteen to twenty miles wide bordering the Yazoo- 
Mississippi Delta. The boundaries may be traced on the sketch 
map. 
The surface of this regicn is that of a maturely eroded 
plateau of varying altitude, from less than 400 to more than 
600 feet above sea level, the higher altitudes being in the north- 
ern parts of the area. Many streams trench the surface, the 
larger having broad flats 100 to 200 feet lower than the Plateau 
surface. Usually two or more terraces fringe the stream val- 
leys. On account of the mature erosicn the original plateau 
has been cut into hills and ridges, the surface being more 
broken and intricately dissected near the larger streams, while 
in the wider areas between streams the original plateau presents 
a gently rolling surface. As may be inferred from the forego- 
ing statements the uplands of the region are well drained. In 
the stream valleys the first bottoms in many places are badly 
drained and occupied with swamp growth, which will be de- 
seribed presently. 
The upland scils of the region present two very well de- 
fined aspects which really constitute two sub-regions, as the 
species occupying the two differ considerably. A north-south 
zone occupying about the east one-half of the area shows clay 
soils similar te those of the Flatwoods, though somewhat 
sandier and the surface more rolling. Over much of the area 
the tops of the hills and ridges are capped with yellow and red 
sandy loam soils; toward the western part of this subdivision 
the sandy soils very much predominate and the topography 
becomes more brcken. These soils, as are those of the Flat- 
woods, are derived from weathering of outcropping clay and 
sand formations of the Eocene Tertiary. 
The western subdivision of the North Central Plateau has 
overlying the eroded surface of the eccene sands a blanket 
