Lost River - Karst Information Portal

2007 NSS Convention Guidebook
Commentary and Discussion
Comparison of the relatively greater number
of terrestrial species recovered from
Indiana’s karst over that of open-air sites shows
the benefit of cave deposits in interpreting
regional vertebrate paleoecology. With
northern lake and bog deposits and southern
caves, Indiana is an ideal laboratory for study
of Quaternary biota. Unlike surface localities,
where impending construction often forces a
salvage-like recovery of mastodont and other
large mammal skeletons, the cave environment
is one in which most investigations can be
methodically planned. Human cave traffic can
be the most detrimental factor for underground
paleontological sites, particularly where such
trace fossils as bear beds, claw marks, and
potential footprints are involved.
Many Indiana caves have been shown to
house rich paleontological resources. However,
many more resources have yet to be discovered,
and it is likely that there are a couple dozen
prolific deposits like those of Harrodsburg
Crevice or Megenity Peccary Cave distributed
throughout both karst areas. Most of the old
deposits are buried below Holocene fill. This
should be true especially of pit caves, where wall
and ceiling disintegration and sediment influx
are accelerated. Open pits, where there may
have been a different type of biotic selection,
have only been superficially investigated in
Indiana. Bears in particular were commonly
entrapped in pits (Figure 10), likely while
Figure 10. The articulated skeleton of a black bear
(Ursus americanus) was recovered where it was
eroding from a sand deposit below the 88-foot
entrance drop of Bear Plunge Pit, Harrison
County, Indiana. David Rieger photo.
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negotiating a slippery entrance searching for a
winter den (Richards, 1984b). One Lawrence
County pit contained the remains of five bears
that had met a similar doom (Richards, 1981).
Most bone deposits were encountered on
cave floors and indicated what lay buried. Some
were exposed where water had eroded through
sedimentary banks, and many occurred as
woodrat den debris. Find the ancient woodrat
dens—occurring both high and low in the
cave—and you will gain audience to an ancient
collection of bones. I have found armadillo
osteoderms (that had obviously been gathered
elsewhere) in woodrat den areas of two
different caves. A woodrat deposit perched high
upon a wall in Carcass Crypt Cave, Lawrence
County, contained a bear vertebra snatched by
the rat from the skeletons on the floor below.
A woodrat midden in Megenity Peccary Cave
contained a beautiful large molar of the extinct
dire wolf.
Even when good deposits are encountered,
there often has been so much dynamic
movement of materials through the cave that
locating deposits with secure stratigraphy
can be difficult. This occurs through cutting
and redeposition of cave sediments by
water, solution of buried limestone along
water channels with deposit slumping, longterm
drying and fissuring of sediments,
and the bioturbation of sediments by such
trapped animals as groundhogs. While most
investigations usually include the removal of
obviously bone-bearing soils surrounding the
fossils of interest, when practical, I try to follow
the caution given by Egyptologist George
Andrew Reisner to physical anthropologist
Carleton S. Coon, who later dug a dozen caves
in the Middle East: “Never quit until you get
down to bedrock” (Coon, 1957). And getting
“plenty” of radiometrically dated bone from a
cave fauna is advice from J. Alan Holman that
the author has heeded well. Often, however,
groundwater has leached the collagen from
cave bones, making AMS dates untenable.
The success at Megenity Peccary Cave is due
in part to fine-screening everything (collecting
“all” vertebrates, using a 1.2 millimeter