Thursday, November 18, 2010

Jeita Grotto - Lebanon

Lower cave at Jeita
The Jeita Grotto is a compound two separate but interconnected karstic limestone caves spanning an overall length of nearly 9 kilometres (5.6 mi). The caves are situated in the Nahr al-Kalb valley within the locality of Jeita, 18 kilometres (11 mi) north of the Lebanese capital Beirut. Though inhabited in prehistoric times, the lower cave was not rediscovered until 1836 by Reverend William Thomson; it can only be visited by boat since it channels an underground river that provides fresh drinking water to more than a million Lebanese.
In 1958, Lebanese speleologists discovered the upper galleries 60 metres (200 ft) above the lower cave which have been accommodated with an access tunnel and a series of walkways to enable tourists safe access without disturbing the natural landscape. The upper galleries house the world's largest stalactite. The galleries are composed of a series of chambers the largest of which peaks at a height of 120 metres (390 ft).
Upper cave at Jeita with the walkway
Aside from being a Lebanese national symbol and a top tourist destination, the Jeita grotto plays an important social, economic and cultural role and is a finalist in the New 7 Wonders of Nature competition.
The Jeita cave is situated at the center of the western flanks of the Lebanon mountains, more specifically in the Nahr al-Kalb valley, its natural entrance is about 100 metres (330 ft) above sea level. It's located 5 kilometres (3.1 mi) east of the Mediterranean coastline and 18 kilometres (11 mi) north of Beirut within the confines of the municipality of Jeita, in the caza of Keserwan.
The Jeita grotto is located within the Lower-Middle Jurassic strata of Keserouane which has a stratigraphic thickness of 1,000 metres (3,300 ft) and consists of dolostone and micritic limestone. The Keserouane formation was exposed to air by a local uplift during the Late Jurassic-Early Cretaceous. The Keserouane strata became karstified after its aerial exposure and then was buried during the Cretaceous. In the Neogene, upon the final uplift of Mount Lebanon, this early karstification phase was reactivated.
Exterior of the Jeita Grotto
At the Nahr al-Kalb valley, the impervious Upper Jurassic volcanic rocks and Lower Cretaceous sand slant almost vertically forming a hydrogeological barrier and forcing the outlet of the Jeita underground river to the surface. This barrier could be the reason for the westernmost, large cave chambers with heights exceeding 60 metres (200 ft). Karstification of the Keserouane limestone was further intensified by the steep topography of the area and the volume of precipitation over the Lebanon (more than 1200mm).
A ratio of total slope gradient of 1/100 is calculated between the entrance of the cave and its inland extremity. This shows its smooth flat course even though it is sometimes interrupted by several small cascades and rapids. From the west, the Jeita cave starts with large halls and meanders. Through some rapids, the dimension becomes narrower. Going forth, it is spacious with the Thompson’s cavern (250 metres (820 ft) long and 60 metres (200 ft) wide), Grand Chaos 500 metres (1,600 ft) long) and Mroueh’s Hall (200 metres (660 ft) long and 50 metres (160 ft) wide). The latter two are floored with collapsed blocks. The cave ends with a Y-shaped pattern, where, each branch ends with a siphon.
The Jeita caves are solutional karst caves which have formed over millions of years due to the dissolution of limestone. The limestone is dissolved by carbonic acid charged rain water and groundwater when the limestone, which is originally water proof, contains cracks produced by tectonic forces the water oozes into the rock and starts to widen the cracks and solute caves inside the layers. Jeita is the longest cave complex in the Middle East, it sits at 300 metres (980 ft) above sea level and has a height difference of 305 metres (1,001 ft). Geologically, the caves provide a tunnel or escape route for the underground river, which is the principal source of Nahr al-Kalb.
The Jeita grotto is the longest explored cave in Lebanon. After many years of exploration, speleologists have penetrated about 6,200 metres (20,300 ft) from the entry point of the lower grotto to the far end of the underground river and about 2,130 metres (6,990 ft) of the upper galleries.
Upper cave
The Jeita upper cave has an overall length of 2,130 metres (6,990 ft) of which only 750 metres (2,460 ft) are accessible to visitors via a specially conceived walkway; access to the remainder of the cave was restricted to prevent ecological damage which may occur due to the flocking tourists. The upper cave contains a great concentration of a variety of crystallized formations such as stalactites, stalagmites, columns, mushrooms, ponds, curtains and draperies. The upper gallery is famous for its formations, lit by an effective lighting system. It is entered through a 117 metres (384 ft) long concrete tunnel. The part accessible by visitors has three huge chambers. The first is called White Chamber, the second Red Chamber, due to the color of the formations. White dripstones are pure calcite without defilement, the red color is given by iron oxide (rust) in small amounts.
In Lebanon iron oxide has a red color instead of the brown beige color which is common in northern countries. The reason is a different chemical reaction caused by the high temperature which produces a different kind of iron oxide. The White Chamber is medium sized, but has the most impressive formations of the cave. The Red Chamber is up to 106 metres (348 ft) high, and 30 metres (98 ft) to 50 metres (160 ft) wide. The third chamber is the biggest of all three chambers and has a height of more than 120 metres (390 ft). The longest stalactite in the world is located in Jeita's White Chamber; it measures 8.2 metres (27 ft) long.
"The Guardian of Time"
Lower cave : The lower gallery which has an overall length of 6,200 metres (20,300 ft) is located 60 metres (200 ft) below the upper gallery. It is traversed by a smooth underwater river and a lake (the "Dark Lake"). The river is broken up by several small cataracts and rapids. The lower cave's "Thompson's Cavern", is a massive hall with impressive speleothems such as the Eagle Obelisk stalagmite. Other halls in the lower gallery include the Pantheon, Grand Chaos and Shangri-la. Visitors are transported in the lower gallery by electric boats for a distance of 500 metres (1,600 ft). In winter the lower level is closed, when the water level is too high.
Today, the Jeita Grotto is a popular recreational show cave and a major tourist attraction. It hosts approximately 280,000 visitors per year.
In 2002, then French President Jacques Chirac, the United Nations World Tourism Organization and the World Bank accorded the top Sustainable Development in Tourism prize to MAPAS (the company that manages the site) at a summit dubbed “New Ties between Tourism and Culture” in Geneva.
In December 2003, on behalf of the Beirut-based private company MAPAS, Jeita received a prestigious award from the fifth Tourism Summits in Chamonix, France. "Les sommets du tourisme" recognized MAPAS’ efforts in restoring Lebanon’s important touristic sites.
The Jeita Grotto is a candidate for the New 7 Wonders of Nature competition. It was selected as one of 28 finalists and is the only cave to be selected among the nominees. The New 7 Wonders Foundation is to announce the new wonders of nature in 2011.

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