Lost River - Karst Information Portal

2007 NSS Convention Guidebook
which has a relatively thicker veneer of terra
rosa than many other nearby areas. Note
that the sinks are fewer in number, and both
shallower and broader than the sinkhole plain
will we cross closer to State Road 37. The Lost
River surficial valley is to the north, and is
beginning to narrow considerably. To the south
about 0.75 miles are many karst fens, which are
wetlands formed in the shallow, broad solution
sinks in this area. Most of the sinks were small
fens before European settlement disturbed the
native landscape.
Continue west into the transitional
boundary between the eastern soil-blanketed
Mitchell Plain and the western sinkhole plain.
County Road 500N will come to the large
Riverview Farms on the north. Note that the
Lost River is immediately to the north and
behind the farm buildings. The first dry weather
sink is 0.25 miles north of the farm, as is a small
in-channel resurgence termed the Orange
County Bluehole (Robert Armstrong, personal
communication, 1991). The first sink is about
1 mile upstream of the principal dry-weather
sinks. The true western sinkhole plain portion
of the Mitchell Plain has now been entered.
Continue to the Intersection of County
Roads 500N and 200E. Turn right (north)
onto 200E. Proceed 0.1 mile to the bridge
over the Lost River with views up and down
the valley (Figures 45 and 46). Note that the
upstream valley has narrowed to about 0.3
miles in width at this point and becomes more
narrow still just downstream of the bridge. The
southern riverbank is also the valley wall, and it
is much steeper than the northern valley wall.
To the north of the bridge the Lost River is still
acting like a normal meandering surface stream
in an alluviated valley, but to the south and
west the river begins to downcut even more
into a distinct channel below the grade of the
Mitchell Plain, and looses the morphology of
an alluviated valley. The sediments are being
carried underground. Miles Cave (2,800 feet)
is one of the eastern-most components of
the underground Lost River, and is located
downstream about 0.75 miles. Miles Cave
exhibits some evidence of being controlled
156
more by bedding planes than vertical joints as
it is up to 20 feet wide, but only 10 feet high
(Bates, 1932, unpublished survey with notes).
In this area of valley narrowing, the probability
of a buried swallowhole with impeded inflow
of storm water is high (Powell and Krothe,
1983).
Turn left (west) onto County Road 500N
and proceed west towards State Road 37 past
Roosevelt Road. Drive across the lower (most
downstream) portion of the alluviated Lost
River valley, up an erosional-alluvial terrace, up
the true valley wall, and then along and up the
southern flank of a large sandstone capped hill
which is an outlier of the Crawford Upland.
The Lost River valley, and the principal dry
weather sinks (unnamed) are about 0.3 miles
away on the south side of the road. Figure 48
has Malott’s original (1949) maps of these and
other features.
Roosevelt Road (Highway 46) is the
original settlement-era road to Paoli from
Orleans. There are good views of the Lost
River valley to the south. Note the fairly
apparent erosion levels in the area. These
represent the pre-Tertiary surface drainage
(Crawford Upland outliers), the Tertiary
surface drainage (Mitchell Plain), and
the Pleistocene subterranean drainageinfluenced
(Lost River) erosion-deposition
surfaces. One mile south (and slightly west)
at the Roosevelt Road bridge over the dry
channel are several smaller storm-water
swallowholes which are about 1 mile east
and upstream of Stein Swallowhole. Stein
Swallowhole, developed in the St. Louis
Limestone, is the first wet weather sink
(Figures 46, 47, and 48B). Following heavy
rains, large quantities of water descend to
the underground Lost River about 25 feet
below the dry bed. Malott (1952) estimated
its capacity at 750 cubic feet per second
from a stream of water 7 to 8 feet deep. A
huge timber raft 100 feet by 60 feet typically
fills the sinkhole and no entry is available to
the cave passages. When Stein overflows,
the storm water travels down the dry bed 2
miles to Turner Swallowhole.