Lost River - Karst Information Portal

2007 NSS Convention Guidebook
at the Ohio River, merges with the cave area
of central Kentucky, the Pennyroyal and
Mammoth Cave Plateaus (Figure 4; McFarlan,
1943, pp 184–187). As shown on Figure 1,
southern Indiana has seven physiographic
units. These units are grossly controlled by the
local lithology and structure (Figures 5B and
6). The Scottsburg Lowland, Norman Upland,
Mitchell Plain, and Crawford Upland are in the
Crawford, Harrison, Floyd, Clark, Washington,
Orange, and Lawrence county vicinity.
The area lies on the flank of the north-south
trending Cincinnati Arch where the rocks dip
into the Illinois Basin (Figures 6 and 7). The
westward dip of the strata is about 25 feet
per mile, but small local structures vary from
this in both rate and orientation. The major
structural deformation of the area is the north-
78
south oriented Mt. Carmel Fault zone and
the syncline and anticline parallel to it on the
west along the western margin of the Norman
Upland. [As an example, cavern development
in the Cave River Valley area has been greatly
influenced by these folds. It is interesting to
note that the outcrop pattern of the rocks,
and thus the physiography, has a fairly sharp
bend in the southwestern Washington County
area. The basin structure and outcrop pattern
runs fairly north-south into northwestern
Washington County where a distinct bend to
the northwest occurs, causing a major widening
of the limestone outcrop and the Mitchell
Plain. The Lost River is developed within the
widened outcrop area, and this is the classic
area of the Mitchell Plain karst topography.
Perhaps future workers could examine more
Figure 1. Physiographic provinces of southern Indiana ( from Powell, 1973).