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HYPOGENIC CAVE FEATURES
Figure 20. Distribution of point feeders (black dots; sub-vertical conduits connecting trunk passages) through the network of master
passages in maze caves: Left = Ozerna Cave, western Ukraine (from Klimchouk, 1990); Right = Coffee Cave, New Mexico, USA (mapped
and sketched by K. Stafford). Lower level passages locally form maze clusters that connect to the master level through sub-vertical point
feeders.
1) Feeders (inlets). Original feeders are basal input
points to hypogenic transverse systems, the lowermost
components, vertical or sub-vertical conduits, through
which fluids rise from the source aquifer. Such conduits
are commonly separate but sometimes they form small
networks at the lowermost story of a system, which bear
the feeding function relative to the upper story. Feeders
join master passages located at the next upper story and
commonly scatter rather uniformly through their networks
(Figure 20). Many feeders are point features; they may join
the passage from a side (Plates 1 and 2), from the end
(Plate 5, A, B and C), or scatter through the passage floor
(Plate 3). Where master networks occur near the base of a
soluble bed, they can receive recharge throughout the
entire length of fissures to guide passage development.
Feeders also can be rift-like features at the floor of master
passages, which extend down to the contact with the
underlying aquifer bed (Plate 5).
Master passages (in multi-story mazes) are passages
that constitute laterally extensive networks within certain
horizons of a soluble unit. They receive dispersed recharge
from numerous feeding channels and represent the lateral
component of flow due to discordance in initial porosity
structure between different horizons. In some complex 3-D
structures, there can be several stories of lateral
development in the system. In that case, feeders of upper
stories are the continuation of outlet features of the
adjacent lower story. Hence, the lower stories function to
recharge the upper stories. Sizes of feeders vary greatly,
from small conduits (tubes, rift-like fissures, etc.) on the
order of tens of centimeters to features many meters in
diameter and tens of meters in vertical extent. In many
instances, dimensions of feeder conduits are smaller in
their lower parts and they often have ear-shaped orifices.
This is due to buoyancy effects, shielding of walls in the
lower parts from dissolution by more saturated water in the
sinking limbs of free convection cells; and to mixing
effects, which cause enhanced dissolution at the orifices
due to mixing of waters of different chemistry.
Feeders are often obscured by the presence of
sediment fill, but still can be identified in many cases by
the presence of rising wall channels, or misinterpreted as
“swallowing” or entrenchment forms rather than forms that
transmitted rising flow.
2) Transitional wall and ceiling features. These
features include rising wall channels, rising sets of
coalesced ceiling cupolas or upward-convex arches, ceiling
channels (half-tubes), and separate ceiling cupolas. They
are usually arranged in continuous series, ultimately
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