Subterranean Phenomena 205 
bluff or steep rocky slope, varying from 30 to 275 feet in height. (See 
Fig. 5.) The most striking feature of the stream and its valley is the 
complex eastwardly turned meander. This meander is more than 3 
miles in circuit and returns to within one-fourth mile of the place 
where it begins. (See Fig. 1.) 
The topographic condition of the area is that of an irregularly 
dissected plain somewhat beyond the stage of maturity. The land forms 
present are far from being uniform in kind and size. Diversity rather 
than uniformity of land forms persist throughout the region. Prominent 
ridges are present, but their crests are individually uneven and rough. 
Rock benches frequently occur on the higher flanks of the valley sides, 
but are not always present there. Great sags and prominent eminences 
occur. The ravines are sharp and rocky, and their upper parts possess 
very steep descents. Local isolated sinkhole plains are present midway 
between the streams and the rough ridge crests. These local sinkhole 
plains are chiefly associated with the valleys of tributary streams in 
their approach to the main valley. Some of the sinkholes have become 
plugged and have become small lake basins. The larger topographic 
features and their relationships are shown on the accompanying topo- 
graphic sketch, Fig. 1. 
The altitudes within the area of the sketch map range between 
510 and 875 feet above sea level. The maximum relief is 365 feet. The 
immediate relief is as much as 275 or 300 feet. The chief relief forms 
are the great bluffs on the outside of the meander turns, the sharp 
uneven sandstone ridges, and the isolated hill within the big meander 
loop. The curved bluffs on the outside of the meander turns are dis- 
EG 2: 
Fig. 2. View of Blue Spring, a large artesian spring which comes from a cavernous 
opening at the foot of the hillside adjacent to Indian Creek. The waters which have 
their exit here have been drained from Possum Valley which lies east of Imdian Creek, 
and have been diverted from their former surface course through the development of 
subterranean channels. The region furnishes an excellent example of subterranean 
stream piracy. 
