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cliff

thumb|right|The [[Trango Towers in Pakistan. Their vertical faces are the world's tallest cliffs. Trango Tower center; Trango Monk center left; Trango II far left; Great Trango right.]]
thumb|right|Europe's tallest cliff, [[Troll wall in Norway. A famous BASE location for jumpers from around the world.]]

In geography and geology, a cliff is a significant vertical, or near vertical, rock exposure. Cliffs are formed as erosion landforms due to the processes of erosion and weathering that produce them. Cliffs are common on coasts, in mountainous areas, escarpments and along rivers. Cliffs are usually formed by rock that is resistant to erosion and weathering. Sedimentary rocks are most likely to form sandstone, limestone, chalk, and dolomite. Igneous rocks, such as granite and basalt also often form cliffs.

An escarpment (or scarp) is a type of cliff, formed by the movement of a geologic fault, or a landslide.

Most cliffs have some form of scree slope at their base. In arid areas or under high cliffs, these are generally exposed jumbles of fallen rock. In areas of higher moisture, a soil slope may obscure the talus. Many cliffs also feature tributary waterfalls or rock shelters. Sometimes a cliff peters out at the end of a ridge, with tea tables or other types of rock columns remaining.

The Ordnance Survey distinguishes between cliffs (continuous line along the top edge with projections down the face) and outcrops (continuous lines along lower edge).
thumb|right|Nanga Parbat, highest cliff (rock wall, mountain face) in the world

Large and famous cliffs

thumb|right|The [[Cliffs of Moher in Ireland]]
thumb|right|Cliffs near [[Sortavala, Russia]]
thumb|right|The Matengai in [[Oki Islands, Japan]]
thumb|Cliffs along the north shore of [[Isfjorden, Svalbard, Norway.]]
thumb|Close-up view of [[Verona Rupes, a 20 km high fault scarp on Miranda, a moon of Uranus.]]

Given that a cliff need not be exactly vertical, there can be ambiguity about whether a given slope is a cliff or not, and also about how much of a certain slope to count as a cliff. For example, given a truly vertical rock wall above a very steep slope, one could count only the rock wall, or the combination. This makes listings of cliffs an inherently uncertain endeavor.

Some of the largest cliffs on Earth are found underwater. For example, an 8000 metres drop over an only 4250 metre span can be found at a ridge sitting inside the Kermadec Trench.

The highest cliff (rock wall, mountain face) in the world, is Nanga Parbat's Rupal Flank in the Himalayas, that rises 4600 metres above its base. According to other sources, the highest cliff in the world, about 1,340 m high, is the east face of Great Trango in the Karakoram mountains of northern Pakistan. This uses a fairly stringent notion of cliff, as the 1,340 m figure refers to a nearly vertical headwall; adding in a very steep approach brings the total height to over 1,600 m.

The location of the world's highest sea cliffs depends also on the definition of 'cliff' that is used. The Guinness record books claim it is Kalaupapa, Hawaii, at 1,010 m high. Another contender is the north face of Mitre Peak, which drops 1683 metres to Milford Sound, New Zealand . These are subject to a less stringent definition, as the average slope of these cliffs at Kaulapapa is about 1.7, corresponding to an angle of 60 degrees, and Mitre Peak is similar. A more vertical drop into the sea can be found at Maujit Qaqarssuasia (also known as the 'Thumbnail') which is situated in the Torssakutak fjord area at the very tip of South Greenland and drops 1560m near-vertically.

Considering a truly vertical drop, Mount Thor on Baffin Island in Arctic Canada is often considered the highest at 1,370 m (4,500 ft) high in total (the top 480 m (1,600 ft) is overhanging), and is said to give it the longest purely vertical drop on Earth at 1,250 m (4,100 ft). There is some doubt as to whether this height is exceeded by other cliffs on Baffin Island or in Greenland, however.

The highest cliff in the solar system may be Verona Rupes, an approximately 20 km (12 mile) high fault scarp on Miranda, a moon of Uranus.

The following is an incomplete list of cliffs of the world.

Asia

Above Sea
Above Land
  • Various cliffs in the Ak-Su Valley of Kyrgyzstan cliffs are high and steep.

Europe

Above Sea
  • St John's Head (Hoy Orkney Islands Scotland) at 335 m is the most vertical sea cliff in the UK
Above Land

North America

thumb|right|[[Mount Thor, Baffin Island, Nunavut, Canada, commonly regarded as the highest purely vertical drop on Earth]]
thumb|right|Southwest face of El Capitan from Yosemite Valleythumb|The face of Notch Peak at sunset
Several big granite faces in the Arctic regions vie for the title of 'highest purely vertical drop on Earth', but reliable measurements are not always available. The possible contenders include (measurements are approximate):
  • Mount Thor, Baffin Island, Canada; 1,370 m (4,500 ft) total; top 480 m (1,600 ft) is overhanging. This is commonly regarded as being the largest purely vertical drop on Earth at 1,250 m (4,100 ft).
  • Ketil's west face in Tasermiut, Greenland (also known as God's Thumbnail), has been reported as 1,400 m - 1,450 m high, (although some doubt has been cast on this).

Other notable cliffs include:
  • Northwest Face of Half Dome, near El Capitan; 1,340 m (4,400 ft) total, vertical portion about 610 m (2,000 ft)

South America

thumb|[[Salto Angel from Raton, Venezuela.]]

Africa

Above SeaAbove Land
  • Tsaranoro, Madagascar, 700 m above base
  • Karambony, Madagascar, 380 m above base.
  • Innumerable peaks in the Drakensberg mountains of South Africa are spectacular cliff formations. The Drakensberg Range is regarded, together with Ethiopia's Simien Mountains, as one of the two finest erosional mountain ranges on Earth. Because of their near-unique geological formation, the range has an extraordinarily high percentage of cliff faces making up its length, particularly along the highest portion of the range. This portion of the range is virtually uninterrupted cliff faces, ranging from 600m to 1200m in height for almost 250 km. Of all, the "Drakensberg Amphitheatre" (mentioned above) is probably the most impressive individual formation. Other notable cliffs include the Trojan Wall, Cleft Peak, Injisuthi Triplets, Cathedral Peak, Monk's Cowl, Mnweni Butress, etc. The cliff faces of the Blyde River Canyon, technically still part of the Drakensberg, may be over 800m, with the main face of the Swadini Buttress approximately 1000m tall.

Oceania

Above Sea
  • The Elephant, New Zealand, has cliffs falling approx 1180m into Milford Sound, and a 900m drop in less than 300m horizontally
  • Ball's Pyramid, a sea stack 562m high and only 200m across at its base

See also


 
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