The Dniester River Valley

A Geopark candidate in Ukraine

Introduction
This paper represents the Dniester River Valley as one of most important georegions of Ukraine. It is based on the National Geological Monuments List (Zaritsky, 1985). Now the State Geological Survey of Ukraine develops this list by sponsoring a national geological prospecting (scale 1:200 000) and at the same time searching, exploring and describing new geosites in order to compiling a national data base.

The Dniester River Valley have many different potential geosites candidates for the International Union of Geological Sciences global inventory of the Earth's geological heritage, or GEOSITES database (Johansson et al., 1998). We work to identify areas of special geological interest, which by conservation and management will contribute to the conservation of the national as well as European geological heritage. Most of the geosites are of stratigraphical importance. The key Vendian and Silurian sections were studied and described by Velikanov et al. (1983) and Tsegelnyuk et al. (1983). Almost all valleys from Yampol village up to Ivane-Zolote village have beautiful exposures almost without interruptions.

The Dniester River canyon is partly flooded by reservoir waters. Its depth reaches near fifty meters at its maximum. Many of the stratotypes and geological sequences are thus covered by water, but others still remain visible. Additionally erosion by the waves in the reservoir is creating new exposures. The special geological and geomorphological setting allows different types of geosites to be identified.

• Stratigraphical geosites (stratotypes of regional series, Formations, sub-Formations and international parastratotype of boundary between Silurian and Devonian).
• Other geosites represent paleontological localities with fossil fauna and flora which give us information on development of prehistoric life.
• Some mineralogical geosites (for instance, N631: outcrops of Vendian deposits which contain concretions of phosphorite with ore mineralization).
• Karstic geosites with caves.

Historical background
In the middle of the 19th century geological investigation of Upper Silurian and Lower Devonian of this region began. It was connected with the investigations of St. Staszic, E. Eichwald and K. Malevsky, whose results were summarized by R. Kozlowsky (1929). There were studies in pre-Skalian deposits and its fauna (Wenjukov, 1899). Regular and extensive examinations of the oldest sedimentary rocks started in the 1920–1930s. For a long time this was a field of interest mainly for Russian and then Ukrainian scientist (Tsegelnyuk et al., 1983, Drygant 1972 and others). An international geological significance of this region has recently been more evident because of:

Fig. 1. In the Jampil sandstone plates numerous imprints of softbody Vendian fossils were found: “Nemiana”, “Tirasiana”, “Medusinites” and others. The picture shows a very good preserved examples of their settlement. Here both positive and negative casts are present. From a quarry created near the Yaryshiv village.

Fig. 2. The Yarouga regional series correspond to the Wenlockian and Ludlovian of the International Stratigraphic Chart. This outcrop show bedded nodular limestones of the Ternava Formation and a hard plate of limestone from the lower part of the Bagovitsa Formation. Right bank of Ternava river near its mouth.

• the occurrence of large outcrops which represents different facies and abundant high quality fossils,
• the almost total absence of folding, weak influence tectonic breaks and metamorphism,
• the general development and need for international cooperation.

New projects are developed, for instance a Great Britain NERC project directed into Vendian environments.

Fig. 3. Outcrop of the upper part of the Malynivtsy regional series. The green vegetation belt is connected with springs which flow from the cover of volcanic ash beds (now bentonite clays). The left bank of Dniester river near Malynivetska Sloboda village.

Geomorphological conditions
The region generally corresponds to the Podolian uplands. The relief is characterized by slightly hillocky plains, highly hydrographically dissected with gullies. The upland declines to the south and the relief can be characterized by a combination of vast flat interfluves and canyon-like valleys oriented almost meridianal and falling towards the Dniester River. A ridge called the Tovtry hills is an important element of the landscape east of Kamianets-Podilsky. This fossil barrier reef of the Middle Miocene Sea forms a whimsical strong rock formation very resistant against weathering and destruction.

Geological setting
The area belongs to the south-western and western slopes of the Ukrainian Shield. Geologically the Middle Dniester area corresponds to the Podolian edge of the south-western part of the East-European Platform or Podolian plate. Sedimentary complexes are separated one from another by regional unconformities. All complexes are developed as

monoclines on the west Slope of the Ukrainian Shield. The Vendian unit inclines westwards and south-eastwards at an average angle of 20 up to 50. The Khmelnitskiy Formation (Cambrian) is represented by a glauconitic sandstone outcropped near the Kytaigorod Village. The lens-like bodies of the Ordovician are represented by two (Goraivka and Souboch) formations of the Molodove Regional series (before named as Molodove horizon) with a total thickness less than ten meters.

Especially important is the sequence from the Silurian (except the Llandoverian) up to the Lower Devonian, which represents the most complete section of these units in platform facies in the world. Only the Silurian total thickness varies from 295 to 470 m. The Lower Devonian is represented both by marine facies (Tiverian Regional Series – 300–400 m) as well as terrestrial ones (Dniestrovian Regional Series – near 500 m), corresponded to Late Lochkovian-Lower Emsian. There are terrigenous beds of “Old red sandstone” facies that contain Placoderms. Mezo-Cenozoic complex is also represented by the Albian-Touronian deposits (flints, silicilits, limestones) separated by a hiatus from Neogene (clayey deposits and limestones). Alpine complex has practically horizontal bedding.

Geosites of the Silurian part of the Silurian-Vendian Sequence
The middle part of the Dniester river basin covers the Khmelnitskiy, Tchernivtsy and Ternopil districts of the Ukraine and is characterized by a platform type structure of the Earth's crust. The crystalline Archean-Proterozoic basement is exposed in the eastern part of the Podolian plateau. Non-metamorphosed sedimentary cover consists of the Vendian (Fig.1) measuring up to 400 m in thickness, Lower Cambrian (up to 120 m), Middle-Upper Ordovician (up to 6 m), and a Silurian sequence with thickness up to 450 m (Fig. 2, 3). Also Lower Devonian sections account for nearly 900 m of sediments (Fig. 4) and Mezo-Cenozoic (up to 30 m).

Fig. 4. A special rolling texture in “old red sandstone” deposits of the Dniester Regional Series near the Ivane Zolote village. Right bank of Dniester River.

Conclusions
At present, many scientists and geologists propose to include the Valley of Dniester River to the European list of Geological Heritage (Gritsenko et al., 1995, Wimbledon, Gerasimenko et al., 1999). In addition, we propose to create a European Geopark here, based on the described Geosites and the general geological quality of the area that includes specialities of high European interest. The territory is close to the Dniester Valley and forms a narrow band of nearly 200 km length. The variety of the area attracts many visitors. The concentration of more then fifty geosites represent different types of Geosites such as Stratigraphical, Paleontological, Paleoenvironmental, Sedimentary-Lithological, Mineralogical, Tectonical, Geomorphological, Hydrogeological, Volcanic, Geo-Archaeological, Geo-Cultural, and Geo-Economical. The middle Dniester River valley is of great interest and a potential for Geological and Natural History education. The region is an arena where geo-hazard processes are common: landslides, mudslides, stream rise (Fig. 5) is occurring frequently and in some places human disturbances (soil and water pollution and consequence effects) adds to this in a way that has great educational potential.

We will propose that the next ProGEO conference in 2006 could be held in the Kyiv with a field trip visiting the best Ukrainian geosites in the beautiful Dniester River basin.

Devonian of Volyn-Podolia, Paleontological sbornik, N5, issue 1, 46–52 (in Russian).

1995. Geological natural monuments of Ukraine: study, reservation and rational use, 61 p.