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HYPOGENIC CAVE FEATURES
multi-aquifer systems are more important in supporting
speleogenesis than zones of descending flow due to more
vigorous circulation and a number of dissolution
mechanisms that can be involved. It is significant that a
hydrostratigraphic setting largely similar to that depicted
by Palmer (1975; 2000b) was used to suggest the uprising
development for maze caves (Ford and Williams, 1989;
Figure 18-C), and this is, in fact, one of the basic settings
discussed throughout this paper in the context of confined
transverse speleogenesis.
Figure 18. Conceptual models of development of a maze cave: A,
B = by diffuse recharge from above (from Palmer, 2000b), C = by
upward flow (from Ford and Williams, 1989).
Ford and Williams also pointed out that the Palmer model
can explain only single-story mazes directly beneath the
sandstone cover. It cannot explain development of multistory
mazes, and mazes occurring without direct contact
with the bottom of the caprock, both being the most
common cases of the structure and occurrence of maze
caves.
Morphologically, there is no unambiguous evidence
reported for maze caves that would suggest a descending
flow pattern during their formation. Instead, at least in
some of the caves referred to in various works to be
formed according to this model, unambiguous evidence for
the rising flow pattern has been recently recognized (the
morphologic suite of rising flow; see next section).
Eventually, those maze caves where a descending origin
could be potentially supposed (where there is a permeable
caprock currently exposed) are in all major respects similar
to the caves where this origin can be definitely ruled out,
e.g. beneath low-permeability cover, and where their
confined transverse origin has been unequivocally
established by bulk evidence.
A maze cave origin is frequently attributed to
hydrothermal speleogenesis, the tendency reinforced by
the paper by Bakalowicz et al. (1987), which suggested a
hydrothermal origin for the Black Hills mazes. Other
known examples of network mazes for which a
hydrothermal dissolutional mechanism is well established
are caves in the Buda Hills in Hungary. However, an
emphasis on hydrothermal dissolution should not obscure
the fact that these caves are attributed to a confined flow
system and rising cross-formational flow, and that maze
caves are known to form by a number of dissolutional
mechanisms.
Frequent association of maze caves and hydrothermal
systems can be easily explained by considering that deep
basinal flow is commonly heated. Where structural and
hydrodynamic conditions allow upward cross-formational
flow, this commonly creates high-gradient thermal
anomalies that favor hydrothermal dissolution. However,
the origin of maze patterns is attributed not to
hydrothermal dissolution (or to sulfuric acid dissolution, as
some other work suggests) but to hydraulic conditions that
favor disruption of the discharge-dissolution feedback
mechanism. It was shown in Section 3.6 that a number of
dissolutional mechanisms can operate in hypogenic
transverse speleogenesis.
The broad evolutionary approach to speleogenesis
implies that caves may inherit prior development through
changing settings. Hence, the problem of cave origin
requires specifying the mechanisms that were operative,
and the features produced, during each of the main stages.
The skeletal outline of a cave pattern is perhaps the most
definite feature that can be attributed to certain recharge
modes and flow systems (Palmer, 1991). As confined
settings commonly pass into unconfined ones, phreatic
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