Harbours and Holocene Variations of the Shoreline Between Andriake
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Méditerranée N° 1.2 - 2005 87 Harbours and Holocene variations of the shoreline between Andriake and Alanya (Turkey) Les variations holocènes des littoraux entre Andriaque et Alanya (Turquie) Eric FOUACHE* Patricia SIBELLA** Rémi DALONGEVILLE*** Abstract - Evidence of Holocene shorelines from Kemer to the Résumé - La mise en évidence de lignes de rivages holocènes border of Syria has been previously shown (EROL, 1963; fossiles au sud de la Turquie, de Kemer à la frontière syrienne, KELLETAT, 1975; DALONGEVILLE and SANLAVILLE, 1977, 1979). In est ancienne (EROL, 1963 ; KELLETAT 1975 ; DALONGEVILLE et the context of the programme entitled «Evolution of coastal SANLAVILLE, 1977, 1979). Dans le cadre du programme de landscapes in the Eastern Mediterranean along the last six recherches intitulé «Évolution des lignes de rivage en millennia», Remi DALONGEVILLE gave us the opportunity Méditerranée Orientale au cours des derniers 6000 ans» et (FOUACHE et al., 1999; FOUACHE, 2001), to revisit this question dirigé par Rémi DALONGEVILLE, nous avons eu la possibilité de on the section of coastline between Andriake and Alanya. The compléter ces observations (FOUACHE et al., 1999 ; FOUACHE, objective was to resume an inventory of coastal formations and 2001). Dans nos prospections nous avons privilégié trois types systematically prioritize three types of markers, the de marqueurs susceptibles de nous aider à positionner les lignes geomorphological markers (notch, beachrock, bench), the de rivage holocènes fossiles : les marqueurs géomorphologiques vermetid bioconstructions, and the archaeological markers (encoche, beachrock, trottoir), les constructions organogènes de (partially submerged quarries, harbour structures), in order to vermets et les marqueurs archéologiques (carrière partiellement reconstruct the variations of the Holocene shore. Harbours, both ennoyée, structures portuaires). Les vestiges de ports antiques et ancient and medieval, are numerous throughout this section of médiévaux sont nombreux sur tout le secteur de côté étudié, mais the coast and incompletely studied (BLACKMAN, 1973a and b, encore incomplètement inventoriés (BLACKMAN, 1973a et b, 1982a and b). The authors’ study is also an opportunity to try 1982a et b). and understand the possible consequences of the relative sea level on the functioning of the better-known harbours. The region under study (Fig. 1) begins at the island shipping in the Gulf of Antalya. From Kemer to Alanya, of Kekova, which is situated five kilometers to the and on to the border of Syria, one can identify markers of southwest of Andriake and was affected by a significant the shoreline that indicate a relative submergence, but the subsidence after an earthquake in the second half of the markers of uplift are particularly dominant 2nd century AD (FOUACHE et al., 1999), and concludes at (DALONGEVILLE et al., 1993; EROL and PIRAZZOLI 1992; Alanya. This rocky promontory is the site of the ancient KELLETAT and KAYAN, 1983). In addition to city of Coacesium, which was a haven for pirates until its geomorphological observations, the archaeological sites destruction by Pompey in 67 BC. The city reached its apex of Andriake, Olympos, Phaselis, Side, Okurçalar and in the 13th and 14th centuries under the Seljuk sultanate, Alanya have also attracted our attention. From the point of when it was the principal maritime arsenal and controlled view of seismic activity over the past half century, this * EA 435, UMR 8591, CNRS, Universités de Paris I et Paris XII, 94010 Créteil Cedex. [email protected] ** Institute of Nautical Archaeology, Texas, USA *** UMR 5133, Laboratoire Archéorient, environnements et sociétés de l’Orient ancien, Maison de l’Orient Méditerranéen, Université Lumière Lyon 2, 7 rue Raulin, 69 007 Lyon. 88 FIG. 1 - HOLOCENE FOSSILE SEA-LEVEL INDICATORS BETWEEN ANDRIAKE AND ALANYA region is also interesting for being located on either side of were undoubtely related to an ancient sea level, that is, the Finike peninsula, which is the border of two well- harbour structures, partially submerged quarries. All these differentiated tectonic zones (Fig. 1). To the west of the indicators do not have the same precision as regards the peninsula, in the zone situated on an extension directly in sea level. The most precise and reliable of all are the front of the Aegean arc, earthquakes greater than vermetid bioconstructions, often linked to benches. Then magnitude 5.0 on the Richter scale are frequent (GLOVER as far as geomorphological markers are concerned, et al., 1998). To the east, in contrast, they are few. One notches are due to the action of the corrosion by the sea at may wonder whether this geological boundary matches up the midlittoral level. The retreat point of a notch with the distribution of geomorphological markers of corresponds to the average sea level (PIRAZZOLI, 1986), ancient shorelines, and whether any tectonic conclusions which makes it a rather precise indicator. However, the may then be inferred. precision decreases with the intensity of the action of the waves on the cliff. As for beachrock, the cementation occurs inside an active beach or under a superficial 1. Methodology presence of cyanobacteria (BERNIER & DALONGEVILLE, 1988; NEUMEIER, 1998) in the intertidal zone and needs a prograding system. Considering the progradation, we have Our objective was to resume an inventory of assumed that the average sea level corresponded to the coastal Holocene sea level indicators between Andriake middle of the fossil beachrock slab. Thus, in a context of and Alanya in order to establish a relative chronology of low tide, such as in the south of Turkey, we have estimated sea level changes. We identified three types of fossil sea the imprecision to ± 20 cm. As for the archaeological level indicators, the geomorphological markers (notch, indicators, in our case they are the most approximative beachrock, bench), the vermetid bioconstructions and the indicators, but they prove extremely useful when archaeological markers. For the latter, taking into account combined with the other indicators, as they provide the methodology developped by FLEMMING (1979-80) and information about either a minimum or a maximum level. PIRAZZOLI (1979-80) we have selected in BLACKMAN (1973 a and b) the submerged archaeological remains that 89 assemblage of beachrock slabs, in the process of breaking up, visible up to five meters from the present shoreline and down to one meter under water. The highest slab, part of which is out of the water but the majority is submerged, includes in a carbonated matrix of nearby pebbles of the same type as the pebbles that constitute the storm cordon of the actual beach. We therefore believe that this slab represents the highest level of the fossil beach, the mediolittoral level of which is found about 0.5 m below the present level. One submerged slab, with the same characteristics as that of Kemer, has been observed as well, thanks to an incision caused by an inlet channel between a costal FIG. 2 - BEACHROCK AT THE MOUTH OF RIVER GÖKSU pond and the sea and established inside a cordon of pebbles at the mouth of the river Göksu (Fig. 2). But it is to the east of Antalya, however, in the vast sandy beaches that dominate that zone and which all recognize today to be an ongoing erosion, where one observes the largest beachrocks (Fig. 1). The submerged slabs are visible along the entire coast, up to several meters from the shore, and down to one meter deep. They appear there also to correspond approximately to a marine level of around 0.5 m below the present level. But both west and east of Antalya, there are also some beachrock that suggest a relative marine level situated above the present level (Fig. 3). 2.2. Some traces of a relative sea level superior to the Modern one between Kemer and Alanya At Kemer, there are pieces of beachrock slabs, FIG. 3 - FOSSIL HOLOCENE BEACH AND BEACHROCK AT THE FOOT 40—50 cm long and 10—15 cm thick and OF THE TRAVERTINE CLIFF EAST OF ANTALYA imbedded in a fossil beach of consolidated 2. Two fossil Holocene shorelines between pebbles which are located under a dune about twenty Kemer and Alanya meters behind the Modern beach. Locally these fragments can be interpreted perhaps as the remains of the Immediately to the west of Antalya, in the rear of submerged slab, displaced by virtue of a storm, but other that gulf, and in the bays of Beldibi and Kemer, large evidence, more and more obvious as one moves eastward, shores have developed in front of dune formations. To the testifies to a stabilisation phase of a relative sea level east of Antalya, once past the developing delta of the Aksu around 0.5 m above the modern level. stream, the beaches become sandy but are always located On Beldibi beach, even more numerous pieces of ahead of dune formations. One encounters a few rocky slabs of the same general shape are visible, while to the sections up to Alanya, the limestone promontory of Side, north of that shore, the foot of the cliff carries the the sandstone cliffs of Okurçalar (which are of local slabs spectacular mark of a large fossil notch partially packed of sandstone detached from the rock in a place that mimics with pebbles, with a highpoint situated 0.5 m above the perfectly a false beachrock), the conglomerate limestone present level. Such a highpoint is not always absolute promontory of Incekum and the one emerging in Alanya. evidence of an ancient sea level but as we move towards This entire section of the coast, to the west and east of the east of Antalya there are more and more incontestable Antalya, presents abundant evidence for fossil shorelines remains of a relative sea level situated above the present- (Fig.1). day level. In effect, the loose formations that occupy the rear of the bays are surrounded by sections of living cliff, which have also preserved, here and there, traces of a 2.1.