Calanque
From Wikipedia, the free encyclopedia
A calanque (or calanche as they are known in Corsican) is a geologic formation in the form of a deep valley with steep sides and a part submerged by the sea.
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[edit] Characteristics
[edit] Location
The best known examples of this formation can be found in the Massif des Calanques in the Bouches-du-Rhône département of France. This range extends for 20 km in length and 4 km in width along the coast between Marseille and Cassis, culminating in Marseilleveyre (432 m) and Mont Puget (565 m). Similar calanques can also be found on the French riviera near Estérel and on the island of Corsica (see Calanches de Piana). Similarities are seen between calanques, and rias, the river mouths formed along the coast of Brittany in Northern France.
The calanques of the Massif des Calanques include the Calanque de Sormiou, the Calanque de Morgiou, the Calanque d'En-Vau, the Calanque de Port-Pin and the Calanque de Sugiton.
[edit] Geology
Calanques are actually remains of ancient river mouths formed mostly during Tertiary. Later, during quaternary glaciations, as glaciers swept by, they further deepened those valleys which would eventually (at the end of the last glaciation) be invaded with sea and become calanques.
Their composition can greatly vary depending on their location:
- Marseille calanques are formed from tertiary limestone.
- Cassis calanques are formed from secondary era rocks deposited by rudist molluscos, before the Cretaceous-Tertiary extinction event.
- Estérel calanques are formed from porphyry and granite going back as early as Primary era.
- Corsica calanques are typically formed from limestone, but some older rocks might also be spotted here and there.
[edit] Ecosystem
The calanques have a particular ecosystem, as soil is almost non-existent there, and the limestone cliffs instead contain numerous cracks into which the roots of plants are anchored. In places where cliffs are less vertical, their vegetation is a classical Mediterranean maquis, typically consisting of densely-growing evergreen shrubs such as sage, juniper and myrtle. It is similar to heath in many aspects, but with taller shrubs, typically 2-4 m high as opposed to 0.2-1 m for heath.
Like anywhere on Mediterranean coast, Calanques' climate is arid, with any moisture coming only from evaporation of the sea. This xericity associated with the salt spray conditions the subsistence of an adapted vegetation.
The calanques also shelter rabbits, foxes, large crows and the Bonelli eagle, as well as many reptiles and wild boars.
[edit] Tourism
The calanques between Marseille and Cassis are popular amongst tourists and locals alike, offering several vantage points (such as the Corniche des Crêtes and Cap Canaille) allowing spectacular panoramas. A great number of hikers frequent the area, following numerous pre-marked trails. The cliffs are also used as training spots for rock 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 still quite fresh and, unlike autumn and winter, rain is usually quite rare. As no fresh water sources are available in the calanques, it is advised to carry large supplies of water, especially during the hot summer to prevent serious dehydration.
Boat tours are also available starting either from Marseille, Cassis or La Ciotat, which can provide for some spectacular sightseeing.
[edit] The Cosquer Cave
The Cosquer cave is an underwater grotto in the Calanque de Morgiou, 37 m underwater, that was once inhabited during Paleolithic, when the sea level was much lower than today.
Its walls are covered with paintings and engravings dating back to between 27,000 and 19,000 BC and depict many terrestrial animals such as bison, ibex, and horses as well as sea mammals like seals and penguins.
[edit] External links
[edit] References
- Collina-Girard, J. (2004a) Prehistory and coastal karstic area : cosquer cave and the “calanques” of marseilles. Speleogenesis and Evolution of Karst Aquifers 2
- Collina-Girard, J. (2004b) La transgression finiglaciaire, l’archéologie et les textes (exemples de la grotte Cosquer et du mythe de l’Atlantide) in : Human records of recent geological evolution in the Mediterranean Basin-historical and archaeological evidence. CIESM Workshop Monographs, n° 24, 152 pages, Monaco, page 63-70
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