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 flat. 

 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 Oreek 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 : 



Soil 12 feet 



Red sand 25 feet 



Blue clay 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 3. 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, leav- 

 ing the soil above to slump into the ravine, which is then in turn rapidly 

 carried 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 



