714 



MARIUS R. CAMPBELL 



Although the evidence given above seems to show conclusively 

 that mounds are not the result of erosion nor of solution, the writer 

 is able to produce more positive evidence that will appeal to every- 

 one, whether he is famihar with the processes of erosion or not. 



During the month of April, 1906, the writer had an opportunity 

 to observe thousands of mounds in the valley of the Arkansas between 

 Little Rock and Fort Smith. They are abundant everywhere on 

 the lowland above the flood- plain of the river, and while many of 

 these have been cut through in grading for railways and highways, 

 it is difficult to find a fresh section in which the structure and compo- 

 sition of the mounds are well shown. At last a mound was found 

 on the Paris road about 3 miles northwest of Dardanelle, Ark., 

 which recently had been dissected by a small stream flowing by the 

 roadside, and a fresh section was exposed. Figure 2 is a photograph 

 of the mound as it appeared in the section. 



Fig. 3. — Diagrammatic section of mound shown in Fig. 2. A is yellowish-white 

 clay. B is soil composed of the clay subsoil reworked with the addition of carbo- 

 naceous material. Mound same as soil. 



The plain upon which the mound appears is flat and composed 

 of a deep subsoil of yellowish- white clay, formed by the decompo- 

 sition of Carboniferous shale. The clay is homogeneous and struc- 

 tureless, except that it shows a tendency to vertical cleavage in much 

 the same way that such cleavage is shown in loess. At the surface 

 and for a depth of from 6 to 12 inches the clay has been opened up 

 and reworked by grass and tree roots, and a small amount of carbo- 

 naceous matter has been incorporated in the clay, giving it a slightly 

 darker color than it had originally. 



The mound which had been dissected was approximately circular 

 before it had been cut away, with a diameter of about 60 feet and a 

 height of 4 feet. The diagram in Fig. 3, which is drawn to scale, 

 gives a good idea of the size and shape of the mound as it was seen 

 in profile. The underlying clay subsoil is shown at A, the ordinary 



