411 
body of the flat in the same manner that the tributaries of Allistons Branch 
are etching their way into the western edge of Flatwoods proper. These 
ravines descend almost suddenly a hundred feet below the level of the fiat. 
In several places the structure of the material can be seen. The upper 
fifteen to twenty feet is a fine, white soil, characteristic of the surface of 
the Flatwoods region. Underneath this, is reddish sand with layers of fine 
gravel alternating with the much thicker layers of sand. Water comes 
from the sand and gravel into the ravine, making them miry in the bot- 
tom. These ravines, in conjunction with the wells (Nos. 21, 22, and 23) 
clearly reveal that the region has been filled, and that the adjunct basin had 
a broad outlet, or opening, to the west. McBrides Creek must have 
extended much farther east, draining in all probability the greater part of 
the adjunct, and having its tributaries reaching to the divide between the 
adjunct and Flatwoods proper. 
It might be mentioned that the streams in section 11 have cut them- 
selves down into the filled material at least fifty feet and leave the old 
flat above as a beautiful terrace. The material of this terrace is shown in 
an excellent manner along the steep western side of the middle stream. It 
is as follows: 
Soliman sy, Mey re oem rie teers oe ae 12 feet 
IRCCUISANGE: waccre ON ese ae he fee Secs oh ee oD Leet 
BIUCRClAVA ee eee a ee oe Sea Se 5 feet 
McBrides Creek undoubtedly had its upper portion and upper tribu- 
taries taken away from it by the forces that remade the topography of the 
region. But it is rapidly working its way back into its old domain in the 
same manner that Allistons Branch is trying to recapture its old basin. The 
rapidity with which these tributaries etch back into the filled material can 
be seen in a single ravine just north of C. R. Ellis’ house in the middle of 
the southeast quarter section 8. The main stream flows parallel with the 
road, and the short tributaries come into it at right angles. These tribu- 
taries are, in fact, just immense gullies only a few rods long, but with the 
depth easily forty feet. The water during showers gushes into these 
ravines and carries away the easily transported sand at the bottom, leay- 
ing the soil above to slump into the ravine, which is then in turn rapidly 
earried away. These ravines grow directly in proportion to the amount of 
water entering them at their head. Mr. Ellis stated that eleven years ago, 
the head of the particular ravine mentioned above was at least sixty feet 
