An escarpment (or scarp) is a type of cliff formed by the movement of a geologic fault, a landslide, or sometimes by rock slides or falling rocks which change the differential erosion of the rock layers.
Most cliffs have some form of scree slope at their base. In arid areas or under high cliffs, they 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 mushroom rocks or other types of rock columns remaining. Coastal erosion may lead to the formation of sea cliffs along a receding coastline.
The British Ordnance Survey distinguishes between around most cliffs (continuous line along the topper edge with projections down the face) and outcrops (continuous lines along lower edge).
Cliff comes from the Old English word clif of essentially the same meaning, cognate with Dutch, Low German, and Old Norse klif 'cliff'. These may in turn all be from a Romance loanword into Primitive Germanic that has its origins in the Latin forms clivus / clevus ("slope" or "hillside").
Given that a cliff does not need to 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 just the rock wall or the combination. Listings of cliffs are thus inherently uncertain.
Some of the largest cliffs on Earth are found underwater. For example, an 8,000 m drop over a 4,250 m span can be found at a ridge sitting inside the Kermadec Trench.
According to some 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 of two stacked pillars; adding in a very steep approach brings the total drop from the East Face precipice to the nearby Dunge Glacier to nearly 2,000 m.
The location of the world's highest sea cliffs depends also on the definition of 'cliff' that is used. Guinness World Records states it is Kalaupapa, Hawaii, at 1,010 m high. Another contender is the north face of Mitre Peak, which drops 1,683 m 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 Torssukátak fjord area at the very tip of South Greenland and drops 1,560 m near-vertically.
Considering a truly vertical drop, Mount Thor on Baffin Island in Arctic Canada is often considered the highest at 1370 m (4500 ft) high in total (the top 480 m (1600 ft) is overhanging), and is said to give it the longest vertical drop on Earth at 1,250 m (4,100 ft). However, other cliffs on Baffin Island, such as Polar Sun Spire in the Sam Ford Fjord, or others in remote areas of Greenland may be higher.
Innumerable peaks in the Drakensberg mountains of South Africa are considered 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 600 m (2,000 ft) to 1,200 m (3,900 ft) in height for almost 250 km (160 mi). Of all, the "Drakensberg Amphitheatre" (mentioned above) is most well known. Other notable cliffs include the Trojan Wall, Cleft Peak, Injisuthi Triplets, Cathedral Peak, Monk's Cowl, Mnweni Buttress, etc. The cliff faces of the Blyde River Canyon, technically still part of the Drakensberg, may be over 800 m (2,600 ft), with the main face of the Swadini Buttress approximately 1,000 m (3,300 ft) tall.
Drakensberg Amphitheatre, South Africa 1,200 m (3,900 ft) above base, 5 km (3.1 mi) long. The Tugela Falls, the world's second tallest waterfall, falls 948 m (3,110 ft) over the edge of the cliff face.
Karambony, Madagascar, 380 m (1,250 ft) above base.
Tsaranoro, Madagascar, 700 m (2,300 ft) above base
Several big granite faces in the Arctic region vie for the title of 'highest 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 (1600 ft) is overhanging. This is commonly regarded as being the largest vertical drop on Earth ot:leapyear at 1,250 m (4,100 ft).
The west face of Notch Peak in the House Range of southwestern Utah, U.S.; a carbonate rock pure vertical drop of about 670 m (2,200 ft), with 4,450 feet (1,356 m) from the top of the cliff to valley floor (bottom of the canyon below the notch)
Shispare Sar southwest face, Karakoram, Gilgit–Baltistan, Pakistan, 3,200 m
Spantik northwest face, Karakoram, Gilgit–Baltistan, Pakistan, 2,000 m
Trango Towers: East Face Great Trango Tower, Baltoro Muztagh, Gilgit–Baltistan, Pakistan, 1,340 m (near vertical headwall), 2,100 m (very steep overall drop from East Summit to Dunge Glacier). Northwest Face drops approximately 2,200 m to the Trango Glacier below, but with a taller slab topped out with a shorter overhanging headwall of approximately 1,000 m. The Southwest "Azeem" Ridge forms the group's tallest steep rise of roughly 2,286 m (7,500 ft) from the Trango Glacier to the Southwest summit.
Cliff landforms provide unique habitat niches to a variety of plants and animals, whose preferences and needs are suited by the vertical geometry of this landform type. For example, a number of birds have decided affinities for choosing cliff locations for nesting, often driven by the defensibility of these locations as well as absence of certain predators.
Humans have also inhabited cliff dwellings.
The population of the rareBorderea chouardii, during 2012, existed only on two cliff habitats within western Europe.
^ abMonika Buchmüller-Pfaff: Namen im Grenzland - Methoden, Aspekte und Zielsetzung in der Erforschung der lothringisch-saarländischen Toponomastik, Francia 18/1 (1991), Francia-Online: Sex nstitut historique allemand de Paris - Deutsches Historisches Institut Paris: OnlineressourceArchived 2015-01-29 at the Wayback Machine
^Max Pfister: Altromanische Relikte in der östlichen und südlichen Galloromania, in den rheinischen Mundarten, im Alpenraum und in Oberitalien. In : Sieglinde Heinz, Ulrich Wandruszka [ed.]: Fakten und Theorien : Beitr. zur roman. u. allg. Sprachwiss.; Festschr. für Helmut Stimm zum 65. Geburtstag, Tübingen 1982, pp. 219 – 230, ISBN3-87808-936-8