Geoscience Reference
In-Depth Information
The cave was discovered and explored at the end
of the 1980s by cavers from ''Prista'' speleoclub—
Rousse. Until now, it is relatively well protected
against human impact and in this sense represents a
good object for palaeoseismological studies. In spite
of this, during the field studies in Troana, we partic-
ularly explored places that were relatively difficult to
reach: niches, old levels of the stream, etc.
Our search for deformations with possible coseis-
mic origin was in the parts up to the first sump of the
Troana Cave. From the comparatively wide range of
palaeoseismic speleoindicators, the following ele-
ments were established there (Kostov et al.
2000
):
(A) Fallen stalagmites. The fallen stalagmites are
the most expressive sismotems. The ''stalagmite's
cemeteries'' (sensu Quinif
2000
) in some caves rep-
resent the best evidence for palaeoseismical activity.
Unfortunately, their quantity in the Troana Cave did
not permit us to accomplish a statistical study of the
preferred orientation of the broken fragments. Only a
few fallen stalagmites (secondarily recovered with
calcite) have been established. The average length of
the stalagmites was 10-20 cm;
(B) Displaced stalactones. One of the attractive
features of the studied cave are the displaced col-
umns. There are observed decametric displacements
Fig. 3.35
Rose-diagram of the directions of 16 fallen and
covered with new speleothems stalagmites
the Troana Cave is one of the remarkable caves in
Bulgaria. The fluvial sediment accumulations in the
main trunk of the cave seem to be several meters in
thickness—an evidence about the high mass transport
energy of the underground stream.
Fig. 3.36
Location of Troana Cave and geological map of the area based on sheet ''Sevlievo'' from the Geological Map of
Bulgaria in scale 1:100 000 (Hrischev and Nedialkova
1992
)
