hayes] TENNESSEE WHITE PHOSPHATES. 421 
of the geologic conditions prevailing elsewhere in the district should 
be of material assistance in locating other deposits. 
The topography of the region between the Tennessee and Buffalo 
rivers has been described in a previous report, but its main features 
may be again briefly described in order to render statements regard- 
ing the distribution of the deposits intelligible. For a considerable 
distance the Buffalo and Tennessee rivers flow north nearly parallel 
with each other, and their tributaries head upon the intervening land 
and join the trunk streams very nearly at right angles, flowing east 
to the Buffalo and west to the Tennessee. The tributaries of the 
Buffalo are very short as compared with those of the Tennessee, so 
that the divide between the two drainage basins is much nearer the 
former stream than the latter. Streams of considerable size enter 
the Tennessee at intervals of about 5 or 6 miles, and shorter ones 
frequently intervene between these main tributaries. 
Beginning in the vicinity of Perryville, the creeks of the first class 
which enter the Tennessee are Spring, Lick, Toms, Roan, and Crooked, 
while the streams of the second class are Parish Branch, between 
Spring and Lick creeks, and Deer Creek, between Lick and Toms 
creeks. These creeks are characterized by rather narrow, level valleys 
and are separated by ridges rising 300 or 400 feet higher than the valley 
bottoms. These ridges are simply portions of a deeply dissected 
upland plateau, the altitude of which in this region is between 900 
and 1,000 feet. They are capped by the Lower Carboniferous chert, 
and are entirely covered with forests. While these ridges reach a 
tolerably uniform elevation, the distance from their summits down 
to the limestone is variable. Thus, in the ridge between Lick and 
Spring creeks the chert is comparatively thin, the limestone reaching 
more than two r thirds of the way from the valley bottom to the top of 
the ridge. The rocks of the region are, in a general way, horizontal, 
though not strictly so, and when considered in broad area they show 
considerable undulations. It should be remarked that the Devonian 
appears to be entirely wanting in this region, the Lower Carbonifer- 
ous chert or cherty limestone resting directly upon some member of 
the Silurian, usually the sparry crinoidal limestone above described. 
The beds descend toward the north, and in Roan and Crooked creeks 
the valleys are not cut down to the surface of the limestone. On 
Toms Creek there is a dip to the west which carries the surface of 
the limestone below the creek valley about 4 miles from its mouth. 
It then rises so that the limestone is exposed between this point and 
the Tennessee River, but again dips westward, and the surface of the 
limestone is probably near the river surface at the mouth of Toms 
Creek. On Roan Creek the limestone is nowhere exposed except in 
the bed of the Tennessee River near its mouth. It will be readily 
understood that the conditions favorable for the deposition and pres- 
ervation of deposits of white phosphate are most favorable in those 
regions where the surface of the limestone reaches a short distance 
