Geoscience Reference
In-Depth Information
Fig. 3.21
Massive stalagmite cut by an open crack. The upper
part of the speleothem is rotated to its base
Fig. 3.22
Anomalous double stalactone in Razhishka Cave
In Razhishka Cave were measured the directions of
16 fallen and deformed stalagmites. The composed
rose-diagram shows the existence of three maxima in
the preferred direction of the deformations: 120-130,
260-270, and 390-400 (Fig.
3.24
). The most well-
defined maximum (390-400) coincides with the
orientation of the cave gallery. However, it is oriented
to the main fault structure in the area—Radov Vrah
reverse fault. It can be assumed that the presence of
deformed stalagmites constituting this maximum is a
result of the disastrous collapse, which ends the cave.
The breakdown in turn, is also likely to be interpreted
as a seismotectonic phenomenon of unknown age.
The other two maxima are with orientation different
from S-N and can be interpreted as a result of sub-
sequent phases of intense seismic activity, depending
on the behavior of the Vratsa tectonic block during
the Pleistocene and Holocene. This block is charac-
terized by intense vertical tectonic movements and
active geodynamic setting.
An eventually absolute dating of the different
deformed speleothems generations in Razhishka Cave
will be beneficial to clarify the Quaternary tectonic
history of the Western Balkan Mountains.
3.3.1.3 Varteshkata Cave
The Varteshkata Cave is a pot-hole, located in Vratsa
Mountain, close to the village of Chelopek, NW
Bulgaria. The vertical entrance is at 1,196 m a.s.l.
This pot-hole is 154 m long with total denivelation
of 74 m and begins with 24 m vertical pit (Fig.
3.25
).
The cave is developed in highly karstified Upper
Jurassic-Lower Cretaceous massive gray limestones
from the Glozhene Formation. The Varteshkata Cave
was discovered and surveyed in 1968 by cavers from
Sofia Caving Club ''Edelweiss'' (Beron et al.
2006
).
The difficult access is a precondition to the conser-
vation of the cave—till now it is rarely visited.
From a morphological point of view, the cave
consists of one large gallery of height more than
