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HYPOGENIC CAVE FEATURES
phreatic conditions. Many other caves have spatial patterns
that do not show any apparent relation to the water table.
The vertical structure of Acquasanta Cave and other caves
in the Rio Garrafo Gorge (Figure 25), entirely developed
under a low-permeability cover, seems to be controlled by
lithostratigraphy and faulting in the core of a formerly
confined but now breached anticline, showing convergence
of the cave development to the breaching point. The caves
of Monte Cucco (Figure 24) demonstrate a largely
structurally controlled pattern. Together with clearly
phreatic (hypogenic) morphology and stratigraphically
controlled vertical heterogeneities in permeabilities, this
suggests a somewhat confined cave-forming environment.
The Faggeto Tondo cave lies under a low-permeability
level of nodular limestone and developed concordant to
bedding within a vertical range of about 300 m. La Grotta
shows the most complex 3-D structure, with multiple
inclined levels within a vertical range of about 930 m. The
Parano Gorge caves are developed largely beneath very
thick, low-permeability marls and sandstones of Miocene
age, partly breached by a gorge (Figure 26). The cave
system has a complex 3-D pattern with multiple levels,
controlled by stratigraphy and fractures (Galdenzi and
Menichetti, 1995).
Figure 24. Schematic cross-section through the Monte Cucco karst system, central Italy (courtesy of Centro Excusionistico Naturalistico
Speleologico Costacciaro: www.sens.it). The main occurrences of massive gypsum are indicated after Galdenzi and Menichetti (1995).
Figure 25. Speleological map on left and schematic cross-section of Rio Garrafo Gorge on right, showing occurrence of Acquasanta caves.
Key: a = marly, cherty limestone; b = low-permeability cover (marls and sandstone). From Galdenzi and Menichetti (1995).
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