124 Hayes and Campbell—Appalachian Geomorphology. 
southern Appalachian region during the long period of degrada- 
tion which it has suffered ought to show gradations from arena- 
ceous to calcareous, corresponding with the stage of develop- 
ment of the cycle in which deposition dccurred, coarse sands 
and clays when a surface subjected to a long period of subaerial 
decay and rock disintegration was elevated so as to stimulate 
stream transportation, and calcareous shales and limestones 
when the surface had been so far reduced to baselevel that only 
fine sediment in suspension or matter held in solution was 
carried by the streams. Since the geomorphy of the interior 
proves the existence of several of these cycles of continental 
development, one should expect to find cycles of sedimentation 
corresponding in geologic age and degree of completeness. 
The record of sedimentation in the Gulf region from the Tus- 
caloosa (probably late Jurassic or early Cretaceous) to the close 
of the Vicksburg or White limestone (late Eocene) is fairly con- 
tinuous and complete. Arranging the formations intervening 
between these limits in their proper order and assigning to each 
a space, not in proportion to its thickness, but to the prob- 
able time occupied by its formation, the curve shown in figure 
3 is derived, in which the horizontal coordinates represent 
relative time, and the vertical coordinates relative coarseness 
or fineness of the sediments. Thus the curve expresses imme- 
diately the variation in character of the sediments carried into 
the sea by the southern Appalachian rivers during Cretaceous 
and Tertiary time and, by inference, the altitude of the land over 
which the rivers flowed. The character and amount of material 
carried off by these streams during the long period of degrada- 
tion preceding the Cretaceous can only be inferred from the 
‘known character and amount of rocks removed for the sedi- 
ments were carried to an unknown distance seaward and con- 
cealed by overlap beneath the subsequent formations. The 
accessible record begins with the Tuscaloosa, a thick deposit of 
sands and clays marking rapid erosion and great carrying power 
of the streams, and hence a considerable altitude of the land 
surface. Through the Eutaw and into the Rotten limestone the 
sediments show a decrease in coarseness and an increase in cal- 
careous matter, and the curve approaches the horizontal axis, 
continuing approximately parallel with it throughout nearly the 
whole of the Rotten limestone. This marks a long period dur- 
