ARTICLE IN PRESS - GeoEcoMarRadu George Dimitriu* Department of Geophysics, National Institute of Marine Geology and Geoecology - GeoEcoMar, 23-25 Dimitrie Onciul Street, 024053 Bucharest,

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Quaternary International xxx (2010) 1e11

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Quaternary International

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Geodynamic and hydro-geological constraints regarding the extension of theprospective archaeo-cultural area within the northern Romanian coastal zone

Radu George Dimitriu*

Department of Geophysics, National Institute of Marine Geology and Geoecology - GeoEcoMar, 23-25 Dimitrie Onciul Street, 024053 Bucharest, Romania

a r t i c l e i n f o

Article history:Available online xxx

Keywords:Romanian Black Sea coastDobrujaGeodynamicsEustasyLittoral erosionArchaeo-cultural heritage

* Tel.: þ40 723 453 930; fax: þ40 21 252 2594.E-mail address: [email protected]

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a b s t r a c t

An obvious discrepancy is noticed between the very few archaeological sites discovered until now on theDanube Delta plain area and the large number of such sites, whose ages range from the Middle Paleo-lithic to the Middle Ages and more recently, identified on its higher topography surroundings.

The combined effects of the regional subsidence of the coast and delta area, with amplitudes of�2 to �4 mm/y and of the secular mean sea level rise (þ0.5/1.0 mm/y) continuously change the “land-mean sea level” relative relationship, placing the prospective archaeo-cultural layer corresponding tothe Late Prehistory e Antiquity period at a burial depth which now exceeds 4e5 m. This situationpartly explains the limited success of the archaeological research carried out until now within theDanube Delta plain area and recommends a systematic use of the geophysical investigation methods infuture. The integrated interpretation of the coastal zone bathymetry and sedimentology mappings andof the shoreline geomorphological evolution in time highlights the sedimentary processes that pres-ently shape the littoral study zone allowing to divide it in sectors where either sediments accumu-lation or erosion processes prevail. The study draws attention to the Împutita e Câsla V�adanei andCosna e Vadu littoral sectors where the intense marine erosion of the shoreline and the adjacentseabed also imminently endangers their prospective archaeo-cultural load.

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1. Introduction

The historical region of Dobruja, also known as Dobrogea (inRomanian), Dobrudja or Dobrudzha (in Bulgarian), is located on thewestern coast of the Black Sea, and is bordered to the west andnorth by the River Danube. Today, the region belongs both toRomania (Tulcea and Constanta counties) and Bulgaria (theadministrative regions of Dobrich and Silistra). The study area(Fig. 1), located in northern Dobruja, entirely covers the DanubeDelta and its adjacent littoral sector.

Although the archaeo-cultural heritage of the Dobruja region isquite impressive, thenumberof archaeological sites discovereduntilnow within the Danube Delta plain area is surprisingly low. Thepaper synthesizes information on this region’s crustal geodynamics,Late Pleistocene e Holocene geological evolution of the DanubeDelta area, and on the recent eustasy, and tries to make a reliableprediction on the extension and burial depth of the prospectivearchaeo-cultural layer corresponding to Ancient times. The paperalso gives an integrated interpretation of the hydro-geomorpho-logical processes which shape the modern littoral and the shallow

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R.G., Geodynamic and hydro/j.quaint.2010.03.001

seabed of the study area, trying to draw special attention to thosesectors where marine erosion causes rapid shoreline retreat andimminently endangers the prospective archaeological heritage.

1.1. Regional setting

The main structural units of the regional basement (Fig. 1) are,from north to south, the Scythian Platform, represented here by thedownthrowncompartmentof thePre-DobrujaDepression, theNorthDobruja Folded Belt, conventionally confined between the Pece-neaga- Camena andSfântuGheorghe Faults (the latter iswell-knownin the offshore as the Sulina-Tarkhankut Fault; Dinu et al., 2005) andthe Moesian Platform, represented by its uplifted Central DobrujaUnit. The lithological units of the Cimmerian folded belt andMoesianPlatformare sealed by thepost-tectonic late Cretaceous sediments ofthe Babadag Syncline, extending beneath the young, unconsolidatedsediments of the southern Danube Delta towards the HistriaDepression on the Black Sea continental shelf. The Danube Deltasedimentary successions include both marine and lacustrine littoraldeposits, fluvial, marsh and loess-like deposits (Panin, 1996).

The Late Pleistocene andHolocene evolution of theDanubeDelta(Fig. 2) includes the following main phases (Panin, 1999): (1) theformation of the Letea-Caraorman initial spit, 9700e5500 BC; (2)

-geological constraints regarding the extension of the prospective...,

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Fig. 1. Study area (dashed line ellipse) located on the north-western Black Sea coast, in the coastal zone of the Northern Dobruja Region, and the main structural units beneath it(regional geological map after S�andulescu et al., 1978, with modifications).

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the formation of the SfântuGheorghe I secondary delta, 7000e5200BC; (3) the formation of the Sulina secondary delta, 5200-0 BC, fol-lowed by its erosion until present; (4) the formation of the Cosna-Sinoie secondary delta, 1500 BCe500 AD, and (5) the formation ofthe Sfântu Gheorghe II and Chilia secondary deltas, 800 BC- present.As Fig. 2 illustrates, due to the delta lobes’ evolution over time, thecoastline also suffered important displacements with notableconsequences on the number and position of the Danube River’sbranches discharging mouths and on the related human activitiessuch as habitation, navigation, and trade.

According to ancient historians (e.g. Herodotus in the 5thcentury BC, Polybius in the 2nd century BC, Strabo in the 1stcentury BC, Pliny the Elder in the 1st century AD, Ptolemy in the2nd century AD and others), that time, the Danube (Istros) Riverdischarged its waters into the Black Sea through five to sevenmouths (branches), among which the most important was theHieron Stoma (Holly Mouth), identified today as being the SfântuGheorghe branch of the Danube (Gâstescu and Stiuc�a, 2006).

1.2. Archaeological heritage

The territory of Dobruja has been inhabited since the Middleand Upper Paleolithic (R�adulescu and Bitoleanu, 1979), as theremains discovered at Babadag, Enisala, and Gura Dobrogei (Fig. 3),among other places, certify. During Neolithic time, Dobruja waspart of the Hamangia, Boian and Karanovo V cultures. Later, at theend of the 5th Millennium, the Gumelnita culture occurred in theregion. During Eneolithic time, the cultural blend of local pop-ulation and tribes originating from the northern Black Sea territorygave birth to the Cernavod�a I to III cultures. Archaeological sites (i.e.

Fig. 2. Holocene evolution of the Danube Delta and the changes of its coastline(compiled from Panin et al., 1983 and Panin, 1999).

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remains of habitation, settlements and tells) belonging to Prehis-toric times, have only been found on the higher lands that borderthe Danube Delta, along the southern distributary of the RiverDanube (i.e. Sfântu Gheorghe branch) at Tulcea, Malcoci, Nuf�aruand along the western bank of the present-day Razelm-Sinoielacustrine complex at Sabangia, Sarichioi, Enisala, Tasburun Hill,Jurilovca, Visina, Lunca, Sinoie Mound, Istria, Vadu, Corbu and CapeMidia (Fig. 3). During prehistoric and ancient times, the Razelm-Sinoie area was a gulf of the Black Sea (Halmyris Bay).

Starting from the 8th century BC, the entire area was dominatedby the presence of the Geto-Dacian population, whose habitationand settlement remains and necropolises were found at Victoria,Bestepe, Dunav�atu along the Sfântu Gheorghe branch and at Eni-sala, Tasburun Hill, S�alcioara, Visina, Istria, Nuntasi and Histriafortress on the western bank of the former Halmyris Bay (Fig. 3).Tumular (mound) complexes, probably of Scythian origin and agesstarting with the 6th century BC, are present in the entire studyarea at Mahmudia, Murighiol, Agighiol, Iazurile, Sarichioi, S�alcioara,Jurilovca, Lunca, Baia Dobrogea, Mihai Viteazu, and Corbu. Thetumuli complexes and the necropolis found respectively at ChiliaVeche and at Caraorman, of unspecified age, probably the 3rde2ndcenturies BC, have special significance due to the presence of theBastarnae tribes within the Danube Delta.

Greek colonization of theWestern Black Sea coast, which startedin the 7th century BC at Histria, is responsible for some of the mostimportant archaeological sites found in the study area: thefortresses of Histria and Argamum (Orgame), the habitationremains at Tulcea, Murighiol, the fortified settlement at Babadag,the settlements from Agighiol, Istria, Nuntasi, S�acele and thenecropolises from Baia Dobrogea (formerly named Hamangia) andMovilele Dese near Histria (Fig. 3). Until now, no archaeological siteof Hellenistic origin has been found on the surface of the DanubeDelta, except for the transit point for merchandise (5the3rdcenturies BC) excavated near Caraorman (Bauman, 2006).

The most numerous archaeological sites discovered until now inthe study area belong to the Roman e Byzantine period, betweenthe 1st century BC and the 13th century AD (Fig. 3), with manybreaks after the 6th century AD due to the pressure of themigrationperiod and the rule of the first and second Bulgarian empires.Archaeological works revealed the fortresses and fortifications builtalong the defensive line of the Danube River: Tulcea (Aegyssusfortress), Ilganii de Jos, Nuf�aru, Mahmudia (Salsovia fortress),Murighiol (Halmyris fortress) and Dunv�atu; and those located onthe north and western banks of the Razelm-Sinoie lacustrinecomplex: west of Dunav�atu de Jos (Zaporojeni fortress), Babadag,Cape Iancina, Cape Dolosman (Argamum fortress) and S�acelesandbank (Histria fortress). Habitation remains and settlements ofthe same age were discovered almost in all localities lying on thesouthern bank of the Sfântu Gheorghe branch and the shore of theformer Halmyris Bay, including Tulcea, Malcoci, Nuf�aru, B�altenii deJos, Bestepe, Mahmudia, Murighiol, Plopu, Sarinasuf, Agighiol,Iazurile, Sabangia, Sarichioi, Babadag, Visterna, Enisala, TasburunHill, S�alcioara, Jurilovca, Visina, Lunca, Ceamurlia de Jos, BaiaDobrogea, Sinoie Mound, Mihai Viteazu, Istria, Nuntasi, ChitucSandbank, Vadu, S�acele, Corbu and Cape Midia.

Relatively numerous remains of habitation and settlements ofmedieval age (9the18th centuries AD), were found (Fig. 3) atTulcea, Nuf�aru, Victoria, Mahmudia, Murighiol, Dunav�atu de Sus,Agighiol, Iazurile, Sabangia, Sarichioi, Babadag, Enisala, TasburunHill, S�alcioara, Jurilovca, Visina, and Vadu. Fortifications remainsdating from the Middle Ages are known at Tulcea, Ilganii de Jos andEnisala (the Heracleea fortress, 15the17th centuries AD). Theremains of the medieval settlements found within the highestlands of the Danube Delta at Chilia, Periprava and Caraorman arealso notable.


Fig. 3. The most important archaeological sites located within the Danube Delta area and vicinity (compiled according to the Romanian Archaeological Record, 2008). A briefdescription of sites is presented in Table 1.


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2. Methods and results

The average level of the Danube Delta topography rangesbetween 1 and 3 m for the fluviatile sandbanks and between 2 and13 m for the marine beach ridges. Due to its flat topography, theentire littoral zone corresponding to the Danube Delta has highvulnerability relative to the recent and present effects of the globalchanges. The continuous modification of the coastline occurringduring the last 11,700 years (Fig. 2), since the Letea-Caraormaninitial spit came into being, reflects the changes of the land-meansea level relative relationship in time. The main causes that changethis relationship are as follows: (1) vertical � horizontal move-ments of the crust originating from geological issues (i.e. regional


subsidence and isostasy) or from global tectonics such as therelative motion of the lithosphere plates; (2) downward move-ments due to soil compaction that affects the young, unconsoli-dated sediments and the loessoid deposits of the Danube Delta; and(3) secular variation of the Black Sea mean sea level.

As a unitary reference system, that could include both infor-mation from the geodetic networks and the tide-gauges in Dobruja,had been lacking until recently, all modifications of the land-meansea level relationship were only relative. The current imple-mentation of ETRS (European Terrestrial Reference System) andEUVN (European Vertical Reference Network) finally allow sepa-ration of the individual contributions of epeirogenesis, sedimentcompaction and eustacy to the overall phenomenon.



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2.1. Crustal movements

The subsiding regime of the Romanian littoral zone and of thenorthern Dobruja was first documented by geophysical-geodeticalmeasurements carried out after 1950 (e.g. Ciocârdel and Esca,1966). Subsidence of 1 mm/y was measured at Mangalia, andover 2 mm/y was estimated for the Danube Delta area, in goodcorrelation with the value of 5 mm/y measured near the DniesterLiman (Fig. 4a). Later geodynamic research (Cornea et al., 1979;Popescu and Dr�agoescu, 1986) found amplitudes of the littoralzone subsidence ranging from 1 mm/y to over 2 mm/y, and highervalues being estimatedwithin the Danube Delta area (Fig. 4b and c).Even higher values of subsidence (2e4 mm/y) have been reportedby Polonic et al. (1999) for the littoral sectors (Fig. 4d). The intensesubsidence of the entire delta area, over the last thousands of years,is also confirmed by elephant and rhinoceros skeletons found(Murgoci, 1912) during the digging of the Sulina Canal, about 6 mbelow the present Black Sea level, and by the position, 2 m below

Fig. 4. Maps of the actual vertical movements [mm/y] of the earth crust in Dobruja: (a) e aDr�agoescu (1986) and (d) e after Polonic et al. (1999).


the present-day groundwater level, of some Hellenistic and Romangraves discovered at Histria.

Geodetic repetitive measurements carried out by Grigore et al.(1996) within the Moesian Platform indicated a 1.14e1.85 mm/yNW displacement of the Dobruja compartment relative to theWallachian one (western part of the Moesian Platform). A generalmovement toward the SSE (2.5 mm/y) of the entire south-easternRomanian territory, including the Dobruja region, is documentedby the recent GPS measurements (van der Hoeven et al., 2005).

2.2. Mean sea level variation

Thefirstmeasurements of theBlackSeamean sea level startedonthe Romanian coast in 1856, at the tide-gauge in Sulina. Later,measurementswere also carried out at the tide-gauges in ConstantaandMangalia. According to the estimationmade byBondar and Filip(1963), based on the data recorded at Sulina and Constanta tide-gauges, the relative Black Sea mean sea level is relatively rising at

fter Ciocârdel and Esca (1966), (b) e after Cornea et al. (1979), (c) e after Popescu and



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þ4 mm/y this value being in good accordance with the values ofþ7mm/y andþ3mm/y reported respectively for the tide-gauges inOdessa and Sevastopol. All these values also include the componentdue to local subsidence and/or soil compaction.

Reprocessing the raw data for longer and longer time intervals,Bondar (1989, 2007) found a value of þ0.5e1 mm/y for the meansea level rise. The author was also able to estimate the subsidenceat Sulina and Constanta at 2.3e3.2 mm/y and 1.7e2.3 mm/y,respectively. These average values of the mean sea level rise are inrelatively good accordancewith those reported by Panin (1996) andCazenave et al. (2002) for the Black Sea, and those reported(Pirazzoli, 1996) for the Mediterranean Sea (þ1.5 mm/y) and for thePlanetary Ocean (þ0.5e3 mm/y).

2.3. Littoral sedimentological processes and shoreline evolution

The shallow waters of the Sfântu Gheorghe e Vadu littoralsector were recently covered (Dimitriu et al., 2008) by a highdensity geophysical lines network (over 4600 km) and a complex

Fig. 5. Bathymetry (a) and sedimentology (b) of the Sfân


sampling network. Sediments, water, biota were sampled over 400selected locations. Fig. 5aeb illustrates the sea floor morphologyand sedimentology of the coastal zone. Comparison with similarresults achieved based on the bathymetry and sedimentology dataacquired about two decades ago clearly highlights the amplitudeand evolution trends of the sedimentary processes that currentlyshape the shoreline and the seabed within the littoral sector.

A generalized shoreward isobath migration trend is noticed asa consequence of the erosion dominance over accumulation. Arelatively unchanged hydro-morphological regime was onlyobserved in the Gura Portita-Sacalin Island sector, at depths greaterthan 20 m. Intense erosion is present off the Sacalin Island e SfântuGheorghe littoral sector, at water depths over 15 m, deepening theseabed by 5e10 m in the last 20 years (Fig. 6a, b). Erosion has alsobeen noticed in the Gura Portitae Perisor sector, within the 5e10mbathymetric interval. Intense seabed erosion (deepening of 3e4 mduring the last two decades) is also present in the Chituc e GuraPortita sector, for the water depth interval ranging from 0 to 10 mand beyond.

tu Gheorghe e Vadu littoral sector of the Black Sea.



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The single relatively stable littoral sector in the entire studyzone was found at Vadu (Fig. 6a, b). The slight seaward shift of theshoreline observed during the last decades there suggests the localdominance of accumulation processes versus the erosion andtransport ones.

A very good correlation between the information regarding thepresence and amplitude of erosion and accumulation sedimentaryprocesses in front of the shoreline, illustrated in Fig. 6, and theactual tendencies of the evolution of the shoreline itself (Fig. 7) isfound for the Sfântu Gheorghe e Sacalin Island and Perisor e Vadulittoral sectors. High retreat rates of the shoreline observed alongSacalin Island (up to 70 m/y) and the Gura Portita e Vadu sector(10e12 m/y) indicate intense erosion shaping the coastal seabed

Fig. 6. Maps of (a) e erosion and accumulation rates [m/y], (b) e seabed depth modificationin the Sfântu Gheorghe e Vadu littoral sector of the Black Sea.


and erasing the remnants of the former Sinoie e Cosna paleodeltabeach ridges, including all its potential archaeo-cultural heritage.

In the sector West Ciotica e Perisor, the shoreline retreat(10e20 m/y) corresponds to a weak accumulation of sedimentswithin the 3e7 m depth bathymetric interval, which is a distanteffect of the continuous elongation westward of the Sacalin spit. Inall cases, the underwater sedimentary processes observed clearlyanticipate the further evolution of the shoreline.

A high pace of shoreline retreat (5�30 m/y) is also observed(Fig. 7) in the Împutita e Câsla V�adanei sector, indicating theintense erosion of the submerged beach ridges belonging to theformer Sulina secondary delta (Fig. 2). A relatively stable shorelineis noticed in the Cardon e Împutita and Câsla V�adanei e Sfântu

[m] and (c) e modification of sand content [%] in surface sediments during 1985e2005


Fig. 7. Present-day tendencies of the Black Sea shoreline evolution in front of theDanube Delta (compiled according to Giosan et al., 1999; Panin, 1999, and Gâstescu andStiuc�a, 2006).


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Gheorghe littoral sectors. An advancing shoreline is only docu-mented for the Sfântu Gheorghe e West Ciotica sector, shelteredand fed by the Sacalin spit island and also in front of the Chiliasecondary delta, advancing up to 68 m/y.

Recent coastal investigations (Dimitriu et al., 2008) also confirmand quantify coarse sediment dominance along the shallow waterlittoral sector, which became obvious during the last two decades(Fig. 6c). Both the increased areal extent of the coarse surficialsediments and their increasing sand content are notable. The sandysediments mainly represent erosion of the paleo-beach ridgesbelonging to the former secondarydeltas. Thefine sedimentsmainlyoriginate from the Danube River, their spatial distribution beingheavily influenced by themarine currents and thewaves directions.

Undoubtedly, the coastline morphology is also heavily influ-enced in this sector by the inflows of water (276 km3/y) and sedi-ments (61 million t/y) brought by the Danube River (65% and 81%,respectively, of the entire inputs) and its northern neighbors (Wonget al., 1994). The drastic diminishing of the Danube River sedi-mentary discharge from a multi-annual average value of over 50million t/y (Bondar and Blendea, 2000) to less than 20 million t/y atthe beginning of the 21st century, combined with other anthro-pogenic or natural causes, clearly disturbed the local balancebetween littoral erosion and accumulation.

3. Discussion

The entire Danube Delta area has an important archaeo-culturalpotential, as demonstrated by its numerous documented archaeo-logical sites (Fig. 3 and Table 1). Compared to the large number of


sites located on the hill system south of the Sfântu Gheorghedistributary from Tulcea to Dunav�at and also on the western bankof the Razelm e Sinoie lacustrine complex, the number of archae-ological sites presently known on the delta plain is unexpectedlylow, despite its undoubted habitation mentioned by the ancienthistorians.

Although the geodynamic and hydro-geomorphological infor-mation has not identified new archaeological sites within theDanube Delta plain, integrated interpretation may outline thoseareas with higher probability to host sites and also to estimate theirburial depth. The interpretation of this information also drawsattention specifically to those littoral sectors whose archaeo-cultural heritage is irreversibly endangered by the current marineerosion.

Research on the Dobruja earth crust geodynamics clearlyascertained the subsidence of the entire coastal and Danube Deltazone. Estimations of the amplitude of the phenomenon generallyrange from 2 to 4 mm/y, which places any prospective archaeo-cultural layer corresponding to the last stage of late Prehistory andearliest Antiquity at a burial depth that exceeds 4e5 m. This couldexplain the lack of success of all archaeological research focused onthe discovery and uncovering of Histria’s and Argamum’s ancientharbours.

Taking into consideration the burial depth of the prospectivearchaeo-cultural layer corresponding to Late Prehistoric e Antiq-uity, the only feasible way to investigate it within the Danube Deltaterritory is offered by geophysical methods: magnetometry, elec-trometry (resistivity, electromagnetics, etc.) ground penetratingradar, high resolution seismic analysis, and others. The applicabilityof these methods is very closely linked to the ability of ancienthuman beings to modify, through their past activities, the habita-tion environment by generating local petrophysical contrasts (i.e.modifications of the normal magnetic susceptibility, density orresistivity of materials, soil and rocks). Such contrasts of physicalproperties, all of anthropogenic origin, which all geophysicalinvestigation methods rely on, were only generated when theancient inhabitants of the Danube Delta realm started to use fire onan increasingly larger scale (producing hearths, ovens, kilns, bakedclay, fired pottery and bricks, etc.), to excavate (ditches, trenches,graves, etc.), to build (dwellings, walls, burial monuments, etc.)especially when using materials of allochthonous origin (stoneblocks, fired bricks, cement, etc.), and to use metallic tools andweapons. According to information gathered on the archaeologicalsites excavated on the adjacent Northern Dobruja, all these stepsoccurred since the 8the6th centuries BC (Early Iron Age), a periodwhen the Dobruja territory was dominated by the presence of theGreto-Dacian tribes, the start of the Greek colonization and thepenetration of the first Scythian groups.

Approximately 800 BC, the Sulina secondary delta was close toits maximum area. The position of the shoreline at that moment ispresented in Fig. 2. The higher lands belonging to the ChiliaPromontory and to the Letea e Caraorman spit, and the marinebeach ridge system to the east, were emerged and suitable forhabitation. After 0 AD, the expansion of the Sulina secondary deltaceased, and the eastern third of its lobe subsequently was eroded.The intense erosion that affects the shoreline of Împutita e CâslaV�adanei littoral sector (Fig. 7) today is an immediate threat to theentire prospective archaeo-cultural heritage hidden within thebeach ridge systems of the Sulina and Sfântu Gheorghe II deltalobes, with ages ranging from the 8th century BC to the 1stcentury AD.

The present position of the inhabited areas suggests the ancientones were also located along the paleo-branches of the Danube, inthe vicinity of the shoreline, at a safe distance from the effects of themajor storms on the sea. Therefore, the most promising areas in


Table 1Location and a brief description of the archaeological sites within the Danube Delta area and vicinity (numbering according to Fig. 3).

Site no. Location Site type Historic period

1 Chilia Veche Village Tumuli complex Unspecified ageSettlement Middle Ages

2 Periprava Village Settlement Middle Ages3 Tulcea Town Habitation Iron age, Hellenistic, Roman and Middle Ages

Settlement Middle Ages4 North-East Tulcea Town “Aegyssus” Fortress Roman and Middle Ages5 Malcoci Village Habitation Settlement Iron age and Roman age 4th-2nd centuries BC6 Nuf�aru Village Habitation complex Eneolithic, Roman and Middle Ages

Fortress complex Roman-Byzantine and Middle AgesSettlement and Necropolis Middle Ages

7 Ilganii de Jos Village Fortress complex Roman-Byzantine and Middle Ages8 Victoria Village Settlements complex 4th-2nd centuries BC and Middle Ages

Necropolis Middle Ages9 B�altenii de Jos Village Settlement Roman age10 Bestepe Village Fortified settlement 4th-3rd centuries BC

Settlement complex and Necropolis Roman-Byzantine age11 Mahmudia Village “Salsovia” Fortress Roman-Byzantine age12 Mahmudia Village Tumuli complex Unspecified age

Habitation complex Iron Age and Roman ageSettlement complex Iron Age, 4th-3rd centuries BC, Roman and Middle AgesNecropolis Iron Age and 6th-5th centuries BC

13 Plopu Village Settlement Roman-Byzantine age14 Murighiol Village Tumuli complex Unspecified age

Habitation complex Eneolithic, Iron Age, Hellenistic and Middle AgesSettlements complex 4the2nd centuries BC, Roman and Middle Ages

15 Murighiol Village “Halmyris” Fortress Roman age16 Dunav�atu de Sus Village Fortress Roman-Byzantine age

Settlement Middle Ages17 Caraorman Village Necropolis Unspecified age

Transit Point Hellenistic ageSettlement Middle Ages

18 Agighiol Village Tumuli complex Unspecified ageSettlement complex Hellenistic, Roman-Byzantine and Middle Ages

19 Valea Nucarilor Village Tumuli complex Unspecified ageSettlement Roman age

20 Iazurile Village Tumuli complex Unspecified ageSettlements complex Roman and Middle Ages

21 Sarinasuf Village Settlements complex Roman age22 West Dunav�atu de Jos Village “Zaporojeni” Fortress Roman-Byzantine age23 West Dunav�atu de Jos Village Settlements complex 4the2nd centuries BC24 South Agighiol Village Habitation complex Neolithic, Roman and Middle Ages25 Sabangia Village Settlement and Necropolis Roman-Byzantine age26 Sarichioi Village Tumuli complex Unspecified age

Habitation complex Eneolithic, Bronze Age, Iron Age, Roman and Middle AgesSettlements complex Roman and Middle Ages

27 Babadag Town Fortified settlements complex Iron Age, 5the3rd centuries BC, Hellenistic, Roman-Byzantine and Middle AgesSettlements complex Roman and Middle AgesFortress Roman-Byzantine ageHabitation Middle Ages

28 Visterna Village Settlement and Necropolis Roman age29 Enisala Village Habitation Bronze Age, 6the5th centuries BC, Roman and Middle Ages

Settlements complex Neolithic, Iron Age, 4the2nd centuries BC, Roman-Byzantine and Middle AgesFortress Roman-Byzantine and Middle Ages

30 East Enisala Village Habitation Iron Age and Middle Ages“Heracleea” Fortress Middle Ages

31 South Enisala Village Necropolis 5the4th centuries BC32 Tasburun Hill Settlements complex Iron Age, 4the2nd centuries BC, Roman and Middle Ages

Tumuli complex 4the3rd centuries BC33 Cape Iancina Fortified Tower Roman-Byzantine age34 S�alcioara Village Settlements complex 4the3rd centuries BC and Middle Ages

Habitation Roman-Byzantine and Middle Ages35 Baia Bobrogea Village Necropolis Hellenistic and Roman-Byzantine age

Settlement Roman age36 Ceamurlia de Jos Village Tumuli complex Unspecified age

Habitation and Settlement Roman age37 Lunca Village Tell Eneolithic age

Tumuli complex Unspecified ageSettlement Roman age

38 Visina Village Settlements complex Iron Age, 4the3rd centuries BC, Roman and Middle Ages39 Jurilovca Village Habitation 6the5th centuries BC, Roman and Middle Ages40 North Jurilovca Village Tumular Necropolis Unspecified age41 Cape Dolosman “Argamum (Orgame)” Fortress and Settlement Iron Age, Hellenistic, Roman-Byzantine age42 Cape Bisericuta Fortified Settlement 5the4th centuries BC, Hellenisctic, Roman-Byzantine and Middle Ages

(continued on next page)


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Table 1 (continued )

Site no. Location Site type Historic period

43 Mihai Viteazu Village Tumuli complex Unspecified ageSettlement Roman-Byzantine age

44 Sinoie Mound Settlements complex Iron Age, 6the5th centuries BC and Roman age45 Istria Village Settlements complex Neolithic, 6the5th centuries BC, Hellenistic and Roman age46 Movilele Dese Tumular Necropolis Hellenistic and Roman age47 S�acele Sandbank “Histria” Fortress and urban settlement 7the3rd centuries BC, Hellenistic and Roman-Byzantine age48 Nuntasi Village Settlements complex 6the4th centuries BC, Hellenistic and Roman-Byzantine age49 North Vadu Village Settlements complex Iron Age and Roman age50 Chituc Sandbank Settlement Roman age51 S�acele Village Settlements complex Hellenistic and Roman age52 South Vadu Village Settlement Roman-Byzantine age53 Corbu Village Tumuli complex Unspecified age

Settlements complex Iron Age and Roman age54 Cape Midia Settlements complex Iron Age and Roman age


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this regard are located in the vicinity of the Sfântu Gheorghe, themost important ancient distributary of the Danube River.

The probability that the beach ridges formed before approxi-mately 500 AD in the Cosna e Vadu sector (Fig. 7), due to thesouthwestward development of the Cosnae Sinoie secondary delta,contain remains of ancient settlements is low. However, there isa high probability of finding remains of fortified points and ship-wrecks, connected with trade between Histria and Argamum andother harbours of the Black and Mediterranean Seas. The relativelynumerous fragments of pottery brought by waves to the beachsouthward of Gura Portita could be reworked from submergedbeach ridges, supporting the hypothesis.

The Lupilor sandbank, that delimits lakes Zmeica and Sinoie,and sandbanks S�acele and Chituc, that border the southern half oflake Sinoie, have high probabilities of containing sites of Romanage, in addition to those discovered at Sinoie Mound and nearVadu (Fig. 3).

4. Conclusions

There is indubitable evidence for an important modificationduring the Late PleistoceneeHolocene time of relative sea level. Anaccurate assessment of the present subsidence and eustasy willonly be possible in the future, based on the geodetic measurementscarried out with the stations of the forthcoming geodynamicnetwork in Dobruja. Based on the long records from the tide-gaugesin Sulina and Constanta, the amplitude of the mean sea level rise isnow appraised at 0.5e1.0 mm/y. The estimates of crustal subsi-dence within the Danube Delta area ranged between 2 and 4mm/y.Therefore, due to both the intense subsidence and the secular meansea level rise, all ancient archaeological sites located within theDanube Delta, previously at low heights above sea level, are nowburied at depths that exceed 4e5 m.

Active erosion and accumulation coexist in front of the DanubeDelta littoral zone. The future extent of the prospective cultural areaand its entire archaeological record in the littoral zone and theadjacent offshore is now heavily menaced by the high erosion ratesobserved in several littoral sectors (e.g. Împutita e Câsla V�adanei,Sacalin spit, West Ciotica e Perisor, Cosna e Vadu sectors) whichcause rapid retreat of the shoreline and seabed deepening of0.25e0.5 m/y (Fig. 6). Over the last two decades, the littoraldepositional environment also suffered a severe change in sedi-ment grain size, sandy sediments becoming dominant.

Among the most important causes that shape the coastline andgenerate the noticed rapid changes of the seabed hydro-geomor-phology are the historical delta front erosion trend, the diminishingDanubeRiver sediment influx, andanthropogenicmodificationof thelongshore sediment transport regime. All these are superimposed on


the regional subsidence of the Danube Delta area and the secularrising of mean sea level.

Due to deep burial and weak petrophysical contrasts betweenanthropogenic and natural features, geophysical detection of anyarchaeo-cultural layer of Paleolithic e Eneolithic age beneath thesurface of the Danube Delta is unlikely. The areas with the highestprobability of hosting a prospective cultural layer at a depth of4e5 m beneath the surface, with an age from the 8th century BC,are the higher lands of the Chilia Promontory, the Letea e Caraor-man spit, and the beach ridge system adjoining it to the east (Fig. 2).

The entire archaeological record, with ages ranging from the 8thcentury BC to the 1st century AD, contained by the Împutitae CâslaV�adanei littoral sector is in imminent danger of being removed bythe intense erosion that affects the shoreline as well as the adjacentseabed. Also endangered by marine erosion are artifacts, mainlyancient shipwrecks, hidden by the beach ridge system developeduntil the end of the 5th century AD in the Cosna e Vadu littoralsector. The sandbanks that border Lake Sinoie are less subject toerosion, and could host some archaeological sites of Roman age andyounger.

Acknowledgments

The interdisciplinary scientific researchof the SfântuGheorgheeVadu coastal sector, carried out in the 2004e2006 interval, wasfunded by the Romanian Ministry of Education and Researchthrough the National ResearcheDevelopment and Innovation Pro-gramme e CERES (Research Project Contract 4-174/2004) and alsoco-funded, until 2006, by the private company “Piscicola Tour”Jurilovca. Partly, the paper is the result of the scientific activitiescarried out in the frame of the National ResearcheDevelopment andInnovation Programme IIe IDEI (Research Project Contract 364/2007 - CNCSIS Code 815). All information regarding the archaeo-logical heritage of the Danube Delta and its surrounding area, whichFig. 3 and Table 1 rely on, are according to the Romanian Archaeo-logical Record webpage, available in Romanian at: http://www.cimec.ro/scripts/ARH/RAN/sel.asp. The author wishes to expresshis gratitude to Dr. MihaelaMelinte (GeoEcoMar research institute),for inviting me to join the IGSP 521 e INQUA 501 scientificcommunity, and last but not least to write this paper.

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ARTICLE IN PRESS - GeoEcoMarRadu George Dimitriu* Department of Geophysics, National Institute of Marine Geology and Geoecology - GeoEcoMar, 23-25 Dimitrie Onciul Street, 024053 Bucharest,