N° 108 - 2007 2 Relative sea-level changes and submersion of archaeological sites along the northern shoreline of the Black Sea Variations relatives du niveau de la mer et submersion des vestiges archéologiques du littoral septentrional de la mer Noire Alexey POROTOV Geographical faculty, Moscow State University Russia [email protected] Abstract - This paper examines archaeological data from the northern Résumé - Cet article synthétise les données archéologiques disponi- coast of the Black Sea to evaluate the possibility of using them as sea-level bles le long du littoral septentrional de la mer Noire. L’objectif est d’éva- indicators for the past 3000 years. Despite the widespread presence of luer leur précision en terme de variation relative du niveau marin depuis submerged cultural remnants, limitations in the use of geoarchaeological 3000 ans. Paradoxalement, la grande richesse de vestiges submergés est as- indicators are related to the disturbance of cultural layers by wave action and sez peu utile pour préciser la mobilité du plan d’eau du fait des remaniements currents, and the scarcity of harbour remains. The review of existing data importants par la houle et les courants et de la rareté des sites portuaires from various sites shows the presence of submerged cultural layers that did fouillés. Cette étude conclut sur la présence d’une couche d’origine anthropi- not exceed 2.5-3.5 m below present, corroborating a slow sea-level rise during que vers 2,5-3,5 m sous le niveau marin actuel, décrivant une montée lente du the first millennium AD. niveau marin au premier millénaire de notre ère. 1 - Introduction The scarcity of geomorphological RSL indicators in the Black Sea during antiquity has led to interest in coastal archaeology, One of the most important questions regarding the Black Sea’s dominated notably by Greek cultural layers. Late Bronze to Holocene paleoenvironments is concerned with the nature Early Iron Age societies and later Medieval cultures did not of Holocene sea-level rise and the reliability of low-amplitude leave notable traces in the coastal area. Within the context of sea-level fluctuations. Interest in palaeoenvironments at the our ongoing research into the paleogeographical evolution of time of Greek colonization of the Black Sea coast has led to the Black Sea during antiquity, this paper reviews sea-level special attention being paid to a speculated 1st millennium BC changes during the Classical period on the basis of archeological regression. Despite archaeological evidence for a low relative and geomorphological data from selected sites. sea level (RSL) during the second half of the 1st millennium BC to the second half of the 1st millennium AD, the amplitude and chronology of the so-called “Phanagorian regression” are unresolved (BALABANOV and IZMAILOV, 1988). RSL mobility for the last 3000 years is important in reconstructing the palaeotopographies and evolution of the Black Sea’s largest ancient cities. There are numerous difficulties in reconstructing RSL changes since antiquity. Small sandy barriers have only been preserved in the inner part of semi-isolated gulfs and limans (e.g. the Gulf of Taman, Kerch strait etc.). On several coastal stretches of the Black Sea, coastline progradation during the subsequent period has buried beach ridges beneath younger coastal sediments. Unfortunately, such coastal archives are not widespread. In light of this, various indirect indicators, mainly lithological, must be used to reconstruct sea-level changes. Fig. 1 - The ancient settlements of the northern region of the Black Sea (after Tolstikov, 1997). For example, the absence of widespread peat layers has been Fig. 1 - Les cités antiques de la mer Noire septentrionale (d’après Tolstikov, overcome using relict beach and nearshore facies, although 1997). these have significant vertical error bars. Further difficulties have arisen due to radiocarbon discrepancies. This has created 2 - South-western Crimea and Bug liman a problem due to the 100-450 year offsets that can exist Underwater research on the south-western coast of the between radiocarbon and historical dates. Until now, much of Crimean peninsula (Fig. 1) has shown the presence of ancient the existing paleogeographical work using archaeological data structures and Hellenistic to medieval period ceramics has ignored the possible discrepancies between different types (BLAVATSKY, 1985; KADEEV, 1969). For example, the submerged of chronology. This calls into question the reliability of many remains lie adjacent to defense walls of the ancient port of existing palaeogeographical reconstructions. Chersonesos. The medieval towers presently lie 0.7-1.0 m 30 A) B) Fig. 2 - A. General plan of Chersonessos (after Tolstikov, 1997). B. Reconstruction of the submerged part of ancient Chersonesos (after ZOLotarEV, 2004): 1 - present shoreline; 2 - shoreline in antiquity (the last centuries BC) at a depth of 3.0-3.5 m ; 3 - stone wreckage (basement of watch tower?); 4 - slipways (?). Fig. 2 - A. Plan de la ville de Chersonèse (d’après Tolstikov, 1997). B. Reconstitution de la partie ennoyée de la Chersonèse antique (d’après ZOLOTAREV, 2004). below sea level. The archaeological material comprises indicate that between the 4th-3rd centuries BC to the 10th-11th amphorae and ceramic fragments from the Hellenistic (3rd to centuries AD RSL lay below present. Sea-level regression is 2nd centuries BC) and medieval (8th to 9th and 12th to 13th attested to by peculiar city planning in the port area, which centuries AD) periods, which not only date the structures, but is characterized by continuous urban expansion from the also attest to the use of an ancient land surface until the 13th 5th-4th centuries BC to the 10th-11th centuries AD. After century AD. Hydroacoustic and underwater archaeological the 12th-13th centuries AD, sea-level rise caused the base of research (ZOLOTAREV and IONES, 1979; ZOLOTAREV, 2004) have “tower XXI” and the southeast outskirts of Chersonesos to elucidated numerous archaeological structures down to be flooded. Archaeological material from the Chersonesos depths of 3 to 3.5 m including harbourworks (moles, jetties coastal area indicates that between the foundation of the city and quays). The results of this study yielded evidence on the and the 10th-11th centuries AD sea level did not reach its extension of the ancient city and have allowed the ancient present position. Changes in urban planning during the 2nd- coastline, presently drowned 3.5 - 5.0 m below present, to be 3rd, 5th-6th, 9th-10th and 13th-14th centuries AD have been located (Fig. 2). Archaelogical research at ancient Chersonesos attributed to changes in economic and political life (BLAGOVOLIN (BLAGOVOLIN and SHEGLOV, 1968 and 1969) has revealed traces and SHEGLOV, 1968) and do not reflect rising sea level during the of historical RSL change. Wells, cellars, fish and water tanks 1st millennium AD (SHILIK, 1997). On the basis of Chersonesos’ located along a coastal strip on the northern part of the city coastal geoarchaeology we propose a RSL curve for the area (Fig. 3). The data are confirmed by our researh on the Kerch- Taman coastline, despite regional differences for the Black Sea (KAPLIN and SELIVANOV, 1999). Ancient Olbia is one of the best investigated underwater sites and has been significant in understanding RSL changes since antiquity. The drowned archaeological remains have enabled a reconstruction of the lower city. The layout of the underwater millier archaeology is given in Fig. 4. The two defensive structures d’années are located 2.0-2.3 m below present and have been constrained (Kyr.) to the 5th to 3rd centuries BC (KRIJISKY, 1984). Remnants of a defensive wall along the palaeo-liman coastline allow the eastern border of the lower city to be delineated. At depths of 2.2-3.1 m two amphora fields have been elucidated: m the first (southern) field yielded material from the 4th century BC, while the second, 50-60 m north of the former Fig. 3 - Relative sea-level changes for the region of Chersonesos (after zone, contains ceramic material from the end of the 6th to BLAGOVOLIN and SHEGLOV, 1968). Fig. 3 - Variations relatives du niveau de la mer à Chersonèse (d’après 4th centuries AD (LEIpuNSKAYA, 1984). Cultural layers from BLAGOVOLIN et SHEGLOV, 1968). the mid-1st millennium AD, on the outskirts of the lower city, 31 do not corroborate the so-called “Nymphaeum” transgression. Coastal stratigraphy has revealed mid-Holocene marine Underwater research at Olbia has shown that cultural layers sediments close to present. Despite the absence of chronological in the outer part of the lower city presently lie 2.5-3.3 m below constraints for this layer, the biostratigraphy allows us to MSL. These remains broadly attest to a mid-1st millennium BC correlate it with a mid-Holocene transgressive stage between sea level at 5.0-4.5 m below present. Ceramics indicate that the 4200 and 3500 years BP. Fragments of this marine terrace lower city continued to function until the 3rd century AD, and are widespread along the shorelines of the Kerch strait. indirectly testifies to moderate RSL changes between the end of Geomorphological data indicate that several coastlines are the 1st millennium BC and the first half of the 1st millennium also located at these depths. One of them has been studied AD. The absence of structures directly related to the sea level by NEVEssKY (1967) and concerns the period 6500 to 6000 yrs does not allow us to be more precise in RSL reconstruction. BP. A preliminary study of the late Holocene palaeo-shorelines Despite the large error margins, this reconstruction is consistent underlines the importance of Kerch’s submerged archaeological with the data from ancient Chersonesos. remains in precisely reconstructing the region’s sea-level The Black Sea’s northwestern limans contain numerous history.