Karst Memorûes Aboye and Beneath the See: Marseilles and ₉₉₉ Continental Shelf During the Cosquer Cave Occupation Jacques Collina-Girard In the south of France, the Cosquer Cave with its famous prehistoric paintings is located in a karstic area located between Marseilles and Cassis. This emerged and submerged karst is typical ofkarstic coasts submerged after the Late-Glacial Maximum. Ail the forms observed in the hinterland can be observed directly by scuba divers and indirectly on bathymetrie charts: lapiaz, karstic archs, sinkholes, uvala and polje. The emerged and submerged land- scapes are mainly the heritage of specifie lithological conditions (Urgonian limestones) and tectonic conditions (vertical faulting network leading to coastal eollapse in the Mediterranean Sea). üther elements of this submerged Iandscape are given by the traces of the last sea level rise (palaeo-shorelines and erosion platforms and notehes). AIl the area between Marseilles and La Ciotat is now established as the Calanques National Park, inc1uding the Cosquer Cave with its upper Palaeolithic rock art paintings, which adds an international archaeological interest to this exceptional natural area. ₉₉₉₉₉₉₉₉₉₉₉₉₉₉₉₉₉₉₉₉₉₉ Continental shelf • Karst • Prehistory • Cosquer Cave • Marseilles 22.1 Introduction be mainly conneeted to three natural factors: specifie Iithol- ogy, specifie structural pattern and typical Mediterranean Along the French Mediterranean coasts, the area between climate. The final toueh is yielded by the postglacial sea level Marseilles and Cassis offers spectacular landscapes, weIl rise submersion ofthis coastal karst. The discovery ofprehis- known over the world to tourists, seuba divers, rock climbers toric paintings in the famous Cosquer Cave (Clottes and and geologists (Collina-Girard 2012). Under a blue sky swept Courtin 1996; Clottes et al. 2005), submerged by the sea and by the northwest wind (mistral), the white of the rocks con- with an opening at -37 m, has added an exceptional piece of trasts with the deep blue of the Mediterranean Sea penetrating submarine archaeology to the celebrity of the Massif des in the hinterland in deep calanques (Fig. 22.1). These land- Calanques, also named Massif de Marseilleveyre. scapes, which are evocative of the coasts of Croatia, Turkey or Greece are located in the immediate neighbourhood of the city of Marseilles. This wild area, known as the Massif des 22.2 Lithology and Coastal Landscapes Calanques, will be soon protected as a National Park. The Between Marseilles and Cassis attractiveness of this emerged and submarine landscape can The Massifde Marseilleveyre belongs geographically to the J. Collina-Girard (Bi) southern calcareous Provence extending from the Rhône Assistant Professor Aix-Marseille 1, Géologie quaternaire Valley (west) to the Mediterranean Sea (south) and to the et préhistoire LAMPEA, MMSH, UMR7269 du CNRS, 5, Rue du Durance valley and the Verdon Canyon (north). Its geologi- Château de l'Horloge, BP647, 13094-Aix-en-Provencc, Cedex 2 e-mail: [email protected]; cal and geomorphological story is marked by the pyreneo- colllnars'mmsb.univ-aix.Ir provencal and alpine orogenie phases and the long-term M. Fort and ₉₉₉₉₉ André (eds.), Landscapes and Landforms ofFrance, World Geomorphological Landscapes, Dar 1₉₉₉₉₉₉₉₉₉₉₉₉₉₉₉₉₉₉₉₉₉₉₉₉₉₉₉₉ © Springer Science-Business Media Dordrecht 2014 230 J.Collina-Girard Fig.22.1 The peak of the vertically faultcd Grande Candelle overlooki ng the Calanque de Sugiton (Photo J. Collina-G irard) evolution of karst relief (Nicod 1967; Julian and Nicod traditionally used in Provence to make kitchen sinks, hollowed 1989; Cavalera et al. 20 10), mostly linked to the Messinian in polis hed Urgonian slabs. These rocks were also exported. period (Mocochain and Clauzon 2010 ; see Chap. 19 in this As an exa rnple, a part of the base rnent of the Statue of book). Liberty in New York was imported from Cassis. Th is homo- Navigating from the we t to the east along the shore from geneous and compact formation is affected by a well- Marseilles to La Ciotat allows to observe the beginning of developed tectonic network dominated by vertical faults the lithological sequence repre ented in the Massif de and joint pattern. Marseilleveyre (Fig. 22.2). The Juras ic unit of the Calanque de Montredon is represented by dolomite trata with ripple marks, mud crack and tromatoliths depo ited in hallow 22.3 Structural Framework of the Karst marine water. The. e formation. are overlain by 400 m of cal- Between Marseilles and Cassis careou maris and lime tone (Lower Cretaceou formations). Above, a main lithological unit (around 250 m) of compact Between Mar. eilles and Cassis. the tectonic frarnework i. bioclastic lime tone , with fos sils of rudists, corresponds to characterised by vertical faults along which the coastal and the Barremi an and Bedoulian ( rgonian) formations. ubmarine areas have subsided to the south and the The karst of the Massif des Calanques is mainly estab- Mediterranean Sea (Fig. 22.1). Their structural lineaments lished on Urgonian limestones, The e white rocks, compact are mainl y W-SE and E-SW and the fault throw could and homogeneou , were extracted as building stone in exceed 300 m. These two directions, W- SE and E-SW. quarries around the city of Ca. sis dur ing the modernisation can be observed, in fractal form , from metric outcrop in the of Marseilles at the end of the nineteenth cent ury and were field to the lin éaments observed on aerial photographs and 22 Karst Memories Above and Beneath the Sea: Marseilles and Its Continental Shelf During the Cosqu er Cave Occupation 231 Fig. 22.2 Geological sketch of Marseillcs and its surroundings, Middle Cretaceous clays: U Lower Cretaceous Iimestones (Urgonian); Legend: TI' Quaternary travertines; 0 clays, sands and pudding stones Ci Lower Cretaceous; J Jurassic dolom ites; F main faults (After J. (Oligocene); Cs Upper Cretaceous Iimestones and conglomerates; Cm Co11ina-Girard 20 12) satellite images. There is also a clear correlation between the orientations of the coasts between Marseille. and Ca is 22.4 Balancing Between Lithological and this structural framework, which constituted the pre- and Structural Causalities: liminary lines for marine erosion during the last ea level Sorne Frequent Karstic Forrns rise (Fig. 22.3). These structural direc tions constitute also the implicit framework explaining the location and the Karst formation is mainly related to the Tertiary period orientation of the karstic thalwegs observed both on the (Eocene and Miocene), but the Lare-Glacial and postglacial continent and on the continental shelf. These directions periods have contributed to give its present aspect to the determine also the location and morph ology of caves and karstic landscapes of the Massif of Marseilleveyre. avens explored by speleologists. A an example, the pla- nimetry of the Cosquer Cave, with its two main chambers oriented 1 E- W, i linked to the same morphostructural 22.4.1 The Calanques framework. ln the same way, the sinkholes submerged on the continental shelf are generally aligned, following the Calanques i the local narne, in Marseilles,of the coastal kar tic same structural trends. valleys penetrating more or les deeply inland. These valleys 232 J. Collina-Girard a NORTH·WEST NORTH-WEST .ft..,.s'.s' !l'A' X ₉₉₉₉₉₉ SOUTH-WEST SOUTH-EAST c;₉₉₉₉ ₉₉₉.s' o. 43° N 20' If Cl * E SW 1 SE Sout h o N ₉I sland Plane I sland o 3,5 km ₉ 'è:::::;:. 1 1 Fig.22.3 Cornparison betwecn the orientation of the coast betwcen Marseilles and Ca . i. (a) and the structural lincaments observed on aeria l photographs and presented in a rose diag rarn (b) (Modilied after Collina-Girard 2012 and S. Dupire 1985) are generally located on fault ed area corresponding to the particularly demonstrative of the widespread structural control structural directions NW and SE. As an example, near Ca. sis, imprinted on the coastline. These coastal valleys, like the fjords the calanque of En Vau i NW-SE, and the nearby calanques of of orway and the rias of Portugal, were partially submerged Port Pin and Port Miou have a NE-SW direction. This case is during the sea level rise following the Last Glacial (Fig. 22.4). 22 Karst Memo ries Above and Beneat h the Sea: Marseilles and Its Conti nental Shelf During the Cosquer Cave Occup ation 233 Fig.22.4 The Cape Morgiou and the karstic Triperie Creek betwccn the Calanque of Sormiou (on the left) and the Calanque of Morgiou (on the rig"'), Cosquer Cave opens at a depth of -37 m (Photo J. Collina-Girard) 22.4.2 Submerged Karstic Arches and Lapiaz Island). The historical quarantine harbour of Port Pomègues (Frioul Islands) is a partially subme rged uvala. Sorne of Scuba divers appreciate the spectacular land cape of subma- these rounded creek correspond to the inactive parts of sub- rine kar tic archs (Fig. 22.5a, b), weil repre ented at the merged karstic valleys or aven aperture (Triperie Creek on outhern part of Maïre 1. land between - 5 and -20 m but also Cape Morgiou, Calanque de Marlet on Frioul Islands). Many on Plane Island at - 35 m and near the divi ng pot of the of these forrns can also he identified from bathymetrie docu- Pierre à la Bague at -45 m. Thi lighthouse announcing the ments (Fig. 22.6) of the continental shelf off Marseilles southern entrance of Marseilles Bay is built on the eme rged (Collina-Girard 1996). This continental shelf terminates at part of a large shoal oriented SW- E from Cap Croisette. the upper limit of the submarine canyons of Messinian origin The flat top of this submarine plateau is an extended karsti- (Planier Canyon, Cassidaigne Canyon). This slope change fied area displaying a spectacular submerged karren or lapiaz occurs approximatively between -150 and - 200 m and (Fig.