Acalanque (French:[kalɑ̃k], "inlet";Corsican:calanca, pluralcalanche orcalanchi;Occitan:calanca, pluralcalancas) is a narrow, steep-walled inlet that is developed inlimestone,dolomite, or othercarbonatestrata and found along the Mediterranean coast. A calanque is a steep-sided valley formed withinkarstic regions either byfluvial erosion or the collapse of the roof of a cave that has been subsequently partially submerged by a rise insea level.[1][2][3]
The best known examples of this formation can be found in theMassif des Calanques (Massís dei calancas inOccitan, the traditional local language) in theBouches-du-Rhônedepartment ofSouthern France. The range extends for 20 km (12 mi) in length and four kilometres (2.5 mi) in width along the coast betweenMarseille andCassis, culminating inMont Puget (565 m or 1,854 ft). Similar calanques can also be found on theFrench Riviera near theMassif de l'Esterel and on the island ofCorsica (Calanques de Piana). The highest points along the calanques are located atMont Puget (565 m or 1,854 ft) and in the mountains of Marseilleveyre (432 m or 1,417 ft).[4] Similarities are seen between calanques andrias, the river mouths formed along the coast ofBrittany in Northern France.
Thelimestone calanques of the Massif des Calanques lie within the recently createdCalanques National Park (2012) and include theCalanque de Sormiou,Calanque de Morgiou,Calanque de Port-Miou andCalanque de Sugiton, which is now accessible only on reservatio during summer. There are additional calanques in the national park, further east along the coast, incised intoCap Canaille. These calanques formed in different rock strata, often in layers of cemented pebbleconglomerate. Calanques are also present in the Italian Apennines, in locations such as theAccona Desert and in theCalanchi natural preserve ofAtri.
Modern day calanques along the Mediterranean Sea are steep-sided valleys that theHolocene (Flandrian) marine transgression partially submerged to form cliff-edged inlets. These valleys were either incised byrivers or created by cave collapse as karstic dry valleys when sea level was lower than at present.[1][2][3]
Along the coast of the Mediterranean Sea, some of the valleys, which were flooded to form calanques, might date back to theMessinian salinity crisis between 5.96 and 5.32 million years ago. During this period of time, the Mediterranean Sea became isolated from theAtlantic Ocean and its surface level dropped as much as 1,500 m (4,900 ft) below the level of the Atlantic Ocean.[5][6] As a result, not only didevaporites accumulate on theabyssal plains of the Mediterranean Sea, but alsorivers flowing into it deepened theirvalleys by hundreds of metres. TheRhône most notably cut acanyon as deep as 576 m (1,890 ft) intoCretaceous carbonate strata near its confluence with its tributary theArdèche. Fluvial erosion by smaller streams and rivers created numerous other deep, steep-sided valleys in response to the greatly lowered sea level at this time.[7] Also at this time, steep-walled, dry karstic valleys were formed by the collapse of caves that developed in limestone, dolomite, and other carbonate rocks in response to the greatly lowered sea level of the Mediterranean Sea.[8] Later, during thePleistocene, these valleys were further enlarged and modified by fluvial, karst, and other processes duringinterglacial drops of sea level within the 100-metre (330 ft) range. During these periods of interglacial low sea level, additional steep-sided valleys, which were later flooded to create calanques, along the Mediterranean coastline were formed by fluvial and karst processes.[9] Today, they can be seen as deep, narrow valleys that are partly submerged by the sea and are made up of limestone or granite.[4]
The calanques have a particularecosystem, assoil is almost non-existent there, and the limestone cliffs instead contain numerous cracks into which the roots of plants are anchored. Nevertheless, the biota is diverse, with over 900 plant species,[10] including a number of endemics like the Marseille Tragacanth and Sabline de Marseille: members of thePapilionaceae family, which can only be found in the hills ofMarseille.[11]
In places where cliffs are less vertical, the vegetation is a classic Mediterraneanmaquis, typically consisting of densely growing evergreenshrubs such assage,juniper andmyrtle. It is similar toheath in many aspects, but with taller shrubs, typically 2–4 m (6.6–13.1 ft) high as opposed to 0.2–1 m (0.7–3.3 ft) for heath. Like elsewhere on the Mediterranean coast, the Calanques' climate is arid, with moisture during much of the year coming only from the evaporation of the sea. This dry habitat associated with salt spray conditions the subsistence of adapted vegetation. The Calanques shelterrabbits,foxes, largecrows andBonelli's eagles, as well as manyreptiles and wildboars.
The calanques between Marseille and Cassis are popular amongst tourists and locals alike, offering several vantage points (such as theCorniche des Crêtes andCap Canaille) allowing spectacularpanoramas. A great number of hikers frequent the area, following numerous pre-marked trails. The cliffs are also used as training spots forrock climbers. However, this excessive use has posed problems of potential damage to this delicate microhabitat.
Most of the calanques are also closed to the public during the summer (typically July through September) due to the risks of forest fire that often happen during the dry season. The best time to visit calanques is probably March through May, when temperatures are cool and, unlike autumn and winter, rain is rare. As no fresh water sources are available in the calanques, visitors are advised to carry large supplies of water, especially during the summer heat, to preventdehydration. Boat tours are also available starting either fromMarseille,Cassis orLa Ciotat, which can provide for some spectacular sightseeing.
In April 2012, most of the calanques were declared a national park due to their uniqueness.[12]
TheCosquer Cave is an underwatergrotto in theCalanque de Morgiou, 37 m (121 ft) underwater, that was once inhabited during thePaleolithic when the sea level was much lower than today. Its walls are covered with paintings and engravings dating back to between 27,000 and 19,000BC and depict many terrestrial animals such asbison,ibex, andhorses as well as sea animals likeseals andauks.[9][13]
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