106 The American Geologist. August,1894 
railroad cuts. Prof. Russell says thatthis weathering extends, 
in some cases to a depth of one hundred feet, but I saw none 
which went so deep in this area. So different in appearance 
are these red beds From the unweatliered rock, that I at first 
took them to be the representatives of a superimposed 
formation of clays. Hut on closer examination, the similarity 
in strike and dip of the clay and of the underlying rock, the 
occurrence in the clay beds of parallel mica plates and other 
minerals of the gneiss, and the continuity of quartz veins 
through the rock and the overlying soils, convinced me that 
the clay was but the weathered phase of the rock. 
It is my purpose to describe a few peculiar topographic 
forms brought about by the long-continued action of the at- 
mosphere on the formation under consideration. The gen- 
eral dip of the rock is to the southeast, but many local folds 
occur id considerable extent. In many places, especially on 
the sides of the low hills, the weathered material has been re- 
moved, leaving large, hare outcrops of rock. These outcrops 
are of two kinds, ( .1 ) flat areas, sometimes several acres in 
extent, and (2) smaller masses which project from the ground 
with the dip of the rock-bed. These projecting ledges are in 
some cases 1(5 feet long, are from 5 to 15 feet broad, and have 
a thickness of -1 or 5 feet. The average dip of the formation, 
and consequently of the ledges, is about 40°, although it i- 
sometimes nearly vertical. In the case of a small fold, near 
Austell, an anticline plunging to the northeast, it was possi- 
ble, in a ploughed field a half mile in extent, to trace the turn- 
ing of the strike from southeast, through east, northeast, and 
north, and this all from one point of view, by means of eight 
of the projecting ledges arranged in a long curving line. 
By the examination of the contoured maps, Atlanta and 
Marietta sheets of the United States Geological Survey, it 
will be seen that this region shows the general characteristics 
of a dissected peneplain, the upland sloping gently toward 
the southeast, having an average hight above sea level of 
1,01)0 feet on its northwestern edge, and 750 feet on the south- 
eastern. On a very small scale, a section crossing this area 
and continuing to the sea is shown in figure '2, plate IV. 
The surface is a rolling hill country in which the streams run 
in two well defined directions. The ( ihattahoochee follows the 
