Download PDF - Speleogenesis

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NCKRI Special Paper No. 1
Figure 40. Map fragment of Jewel Cave, South Dakota, USA, showing superposition of different passage stories. Map by H.Conn and
M.Wiles, courtesy of Jewel Cave National Monument. This is a type example of a multi-story maze pattern.
Mystery Cave in Minnesota is believed to be an
example of a floodwater maze formed by a subterranean
meander cutoff of a small river (Palmer, 2001; Figure 41).
The cave is a 21-km long, relatively widely-spaced multistory
maze developed in sub-horizontal stratified
Ordovician limestones. The cave has perfectly expressed
the morphologic suite of rising flow as described in
Section 4.4 (see Plates 1-E; 6-I; 7-C; 9-D and 14 for
photographs of the cave's hypogenic morphology).
Modifications due to epigenetic overprint are represented
mainly by horizontal notching and are most concentrated
in a few central passages (Plate 14, upper left photo). They
do not override hypogenic morphology even in these major
flow routes. The cave is a good setting for a detailed
analysis of the overlap of epigenic development in a
hypogenic cave.
Several network maze caves and complex 3-D cave
structures occur in Texas, developed in various sections of
the thick stratified Cretaceous carbonates. Special
examination of some of them, performed recently by G.
Schindel and the author, strongly suggests their hypogenic
transverse origin.
Robber Baron Cave is a network maze, occurring in
several levels within a 16-m thick limestone interval of the
Austin Chalk, a distinct unit in the upper part of the
carbonate succession. The cave lies above the upper
confining unit of the regional Edwards Aquifer. The
mapped length of the cave is 1.33 km, probably only a part
of the existing system (Figure 42; Elliott and Veni, 1994;
Veni, 1989). One particular level is a master level, within
which most of the passages are developed. The
possibilities that are alternative to the confined per
ascensum genesis - origin by diffuse recharge from above
and by backflooding - can be definitely ruled out due to
local conditions. The cave clearly displays all the features
of the morphologic suite of rising flow (see Section 4.4
and Plates 2-C and 3-F). It was clearly formed under past
confined conditions, probably due to rising flow from the
presently confined Edwards. There are major springs in
proximity to the cave, which discharge water from the
Edwards through the Austin Chalk, a likely analogue of the
past situation at Robber Baron Cave.
Figure 41. Mystery Cave, Minnesota, presumed to form as a
subterranean meander cutoff of the West Fork of the Root River
(from Palmer, 2001). However, the cave morphology strongly
suggests a hypogenic origin (see Plate 13).