Geoscience Reference
In-Depth Information
Fig. 3.4
Deformations of speleothems by exaration activity: 1 Initial position; 2 Filling the gallery with ice; 3 Movement of the
glacier with breaking of a stalagmite; 4 Present situation (Gilli
1999
)
strangely deformed massive speleothems in Pyrenean
caves—''cemeteries'' of a cave bear. The deforma-
tions
(2) The cave is situated at the lowest point of a large
karst depression (polje, blind valley, or uvala) where
it is possible to accumulate a barrage of devastating
impacts.
(C) Impact of ice movement;
Dr. E. Gilli from the Center for Karst Studies in
Nice presented the hypothesis that in some caves,
speleothems breaking is possible as a result of the
movement of underground Würm glacier (Gilli
1999
)
(Fig.
3.4
). The model study of Lundberg and
McFarlane (
2012
) for Kents Cave, Devon, UK, shows
that up to 3 m thick sediments can be frozen in con-
stant low temperatures of -10 to -15. The freezing
could fracture flowstones up to 13 cm thick. Nowa-
days, the idea of exaration effect on the cave's mor-
phology and sediments is widely accepted by many
karstologists (Kempe
2004
; Becker et al.
2006
). In
our opinion, this hypothesis is not applicable for all
cave areas and is suitable for karst massifs located
near the snow line of the last glacial period.
The precise analysis and logical ignoring of the
described
(fallen
stalagmites)
near
bear
dens
can
be
interpreted
as
a
result
of
the
activities
of
Ursus
Spelaeus. (Gilli
1995
).
(B) Effects of subsidence or landslides of fluvial
cave sediments;
The fluvial cave deposits are represented by sands,
shales, and siltstones. Depending on the morphology
of the cave and the conditions of sedimentation, their
thickness can possibly exceed 7-8 m. In caves with
active hydrodynamic regime, slow movement of these
sediments, subsidence, and landslides in some pas-
sages near the cave river can be observed (Fig.
3.3
).
In case of formation of speleothems on fluvial
deposits, slow inclination or failing is possible.
In the French cave is established very rare break-
age of stalactites by mud-stone torrent (Vanara
1997
).
The preconditions for the emergence of such a cata-
strophic geomorphologic phenomenon are the fol-
lowing: (1) The cave is a shallow hole (ponor) with a
narrow entrance and a minor section of galleries;
possible
causes
of
deformation
of
