Applicatopn dossier for nomination as a European Geopark ...

Overlapping rocks are submitted, as a rule, by sandy
loams and loams of Khvalynian age. N.A.Gvozdetsky
(1981) refers the karst of this area to the covered type.
At the same time there are also local sections of the
open karst. They basically are characteristic of large
karstic-erosive hollows of a superficial drain (Belaja,
Pezcherskaja, Sharovskaja) and natural hollow
Sharbulak.
For the area of lake Baskunchack G.V.Korotkevich
gives the size of karst forming activity - 3,25mm / year.
The karstic relief of the area of lake vicinities develops
from superficial and underground karstic forms.
To superficial forms of karstic relief on the given area it
is possible to include craters and hollows.
The largest forms of the karstic superficial relief in the
given area are karst-erosive hollows of a superficial
drain. They are developed basically on the western part
of the northern gypsum field.
To underground forms of a karstic relief in the given
area can be referred karstic wells and caves. To karstic
wells vertical cavities connected to a zone of vertical
descending circulation of karstic waters concern.
The largest karstic cave of PriCaspian lowland is
"Baskunchakskaya". According to the Saratov section
of speleology the cave has the extent of 1480,0m, the
maximal depth is about 32,0m, its volume is about
9400,0m3. It is situated on the northwest coast of
Baskunchack in top reaches of the superficial drain
Pezcernaja.
Cave "Baskunchakskaja" has some inputs and
concerns to the type of horizontal through (through
passage) caves; it has been known for more than
hundred years. It is actively visited nowadays.
Golovachev I.V. describes three tens caves in
gypsums with the extent of more than 10,0km., but only
7 of these caves are examined and there are published
data about them.
The accumulative plain adjoins to the lake
Baskunchack. According the geomorphological
expressiveness it is subdivided into two subtypes:
gently-wavy which is deposited on the hypsometric
level 0 - minus 10m and flat located on absolute marks
from minus 10m up to minus 21,2m (isohypse, outlining
the lake).
The flat sinuosity of the plain of higher hypsometric
level is caused by non-uniform accumulation of
deposits, drifted from peneplains and the differentiated
display of hydrochloric tectogenesis.
From the surface the plain is combined by early
Khvalynian adjournments which are blocked from
above by dealluvial ones, with the impurity of chippings,
brought from the mountain and adjoining to peneplains.
The flat plain is a part of the lake bottom and is
combined from a surface by oozy deposits of a lake
origin with the impurity of small salt crystals.
The width of accumulative plain varies from 3km in the
settlement Nizchny Baskunchack is up to 0,5km in the
southwest part. The relief is complicated with hollows of
a drain which through peneplains cross the
accumulative plain.
Lake Baskunchack is a unique form of a relief - mould,
filled with halogen type of deposits. Prior to the
beginning of industrial development of salt the whole
12
surface of lake represented a dense salt layer.
Geophysical investigation has shown that salt is
deposited up to the depth of 600m, but deep from the
surface it alternates with sand, clay. In the plan the
lake has the wrong form with the general orientation
in a northwest direction. The extent of the lake on the
big axis is 18 km, the general area is 106 км2. The
significant part of the lake area (60 %) as a result of
salt extraction is occupied by broken zones. These
zones represent sections from which salt is taken up
to the depth of 8m. Broken zones are filled with brine
with a mineralization of 300 g/l. Natural process of
salt accumulation is broken.