TRANSFORMATION OF ISLAND IN PENINSULA IN THE REGION OF THE
TOWN OF POMORIE (E BULGARIA)
M. MATOVA
Geological Institute, Bulgarian Academy of Sciences, Sofia 1113, Bulgaria
e-mail: matova@geology.bas.bg
The town of Pomorie is situated in the central
part of the wide Bourgas bay. It is 21 km to NE
of the town Bourgas. Now the town is developed
over the small Pomorie peninsula (3 km in length,
1 km in width, 5-7m in height). It is correctly to
mark that the old town of Pomorie was placed only
over a small island. The town has very rich
political, economic and cultural history. Later,
the island was connected with the coast by two sand
barriers (tombolo). The Pomorie lake-laguna (6 km
in length, 0.8-1.8 km in width, 1.5 m in depth and
with 60-80% salinity) is placed between the two
barriers (30-200 m in width). So the island was
transform in a peninsula as a result of the
development of the barriers. The recent town and
the railway were built over the island, the sand
barriers and the coast. The Pomorie lake is used for
the salt production and the mud-curing. The town
has a famous balneological center. Its wines and sea
salt production is reputed in their high quality.
The Sarmatian calcareous sands are represented
in the Pomorie island. Two Quaternary sand
barriers are located mainly to the N and
the NW of the island. The cited barriers had realize
the connection between the island and the coast. So
the Pomorie peninsula was formed. It could be
interpreted as a result of constructive tendencies
of the development. The peninsula is a Quaternary
structure. It is subjected mainly to the sediment
accumulation. Now there are a permanent
sedimentation over the sand barriers and the coast.
The quantity of the sand is very considerable.
The Quaternary formed peninsula structure is not
well stabilized.
The peninsula is subjected also to the destrucive
processes. The destructive processes are
represented by the sea erosion, the changes of the
sea level, the epirogenic and the tectonic
movements.
The cited barriers are transformed and partially
destroyed by the constant and small sea erosion,
also by the periodicaly occured strong sea erosion.
The constant erosion is of limited influence. Its
effects are located generally to the E and to the S of
the Pomorie lake. The strong erosion, going up to
the partial barrier’s destruction, is due to the every
4-5 years repeated sea storms. The barrier’s
destruction is realized mainly in the northern part of
the lake’s coast. The town Pomorie is transformed
into island during the cited periods. Several of the
secondary transformation of the peninsula in an
island are marked in the historic documents. The
summary effect of the sand barrier’s destruction is
of value of 12 mm/a (Marinski, 1998). The negative
vertical epirogenic movements of value up to 2
mm/a are established in the Bourgas bay. The sea
level
is
rising
with
an average values of 3.0 mm/a (Marinski., 1998) in
the second half of the the 20th century, despite
the above mentioned epirogenic subsidence. Some
of the antique parts of the town are covered by
the sea water now. The tectonic, including
the seismic activity of the territory is not
considerable. The local seismic events could be of a
maximal magnitude value M<5.0 (Bune et al.,
1982).
The recent geoenvironment conditions could be
characterized by a general constructive tendency
and by several secondary destructive ones.
The intensive sedimentation and the evolution
of the sand barriers (tombolo) are very important
for
the development of the town in the past, now and in
the future. The destruction of the sand barriers is
of a relatively limited significance and of a temporal
manifestations. The cited effects needs special
attention and technogenic activity.
The long-term stability of the town and
the peninsula in the future is problematic, if the rise
of the sea level will be prolonged. The protection
of the town of Pomorie and the Pomorie peninsula
is of national and international significance.
REFERENCES
Bune, B.I., Vuchev, V.T., Gitis, V.G. & Mironov,
M.A. 1982. Application of the interval expert
evaluation approximation method to compilation
of M max maps of Bulgarian earthquakes. Geologica Balcanica, 12,2, p. 49-70.
Marinski, J. (Edit.-in-Chief). 1998. Protection and
long-term stabilization of the slopes of the Black
Sea coasts. Acad. Publ. House “Prof. M.
Drinov”, Sofia , 199 p.
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