SEDIMENTARY PROCESSES/Landslides 687 of palaeokarst may be complicated by two factors; it is usually visible only in two, rather than three, dimensions; and burial by younger rocks does not prevent palaeokarst being modified or even destroyed by subsurface dissolution Small-scale karst microsculpting with relief of a few centimetres, such as rillenkarren or solution pits, is readily destroyed by pressure solution associated with rock overburden Lithological contrasts commonly act as a focus for water movement and the development of interstratal karst, which may resemble palaeokarst but is younger than the overlying rock Interstratal karst is especially prevalent in highly soluble rocks such as gypsum and rock salt Cave passages may remain open as potential conduits for water flow long after burial of the karst surface, and sometimes are invaded and infilled by mineralising fluids Such occurrences may be difficult to distinguish from syngenetic mineral deposits, in which conduit formation and mineralisation were penecontemporaneous, but mineralized palaeocaves commonly include some clastic sediment infill beneath the mineral deposits Remains of organisms within caves are protected from destruction by weathering and scavengers; hence palaeokarst caves encompass many important fossil lagerstaătten Although some animals are adapted for life in caves, most remains found are of animals and plants washed in or fallen in from the surface See Also Engineering Geology: Geomorphology; Subsidence; Ground Water Monitoring at Solid Waste Landfills Minerals: Carbonates Mining Geology: Hydrothermal Ores Sedimentary Environments: Carbonate Shorelines and Shelves; Lake Processes and Deposits Sedimentary Processes: Erosional Sedimentary Structures Sedimentary Rocks: Dolomites; Evaporites; Limestones Unidirectional Aqueous Flow Further Reading Ford DC and Williams PW (1989) Karst Geomorphology and Hydrology London: Unwin Hyman Gunn J (ed.) (2003) Encyclopedia of Caves and Karst Science London: Routledge Klimchouk AB, Ford DC, Palmer AN, and Dreybrodt W (eds.) (2000) Speleogenesis: Evolution of Karst Aquifers Huntsville, AL: National Speleological Society Jennings JN (1985) Karst Geomorphology Oxford: Black well Lowe DJ and Waltham AC (2002) Dictionary of Karst and Caves Bridgewater, UK: British Cave Research Assoc Palmer AN (1991) Origin and morphology of limestone caves Bulletin of the Geological Society of America 103: 21 Simms MJ (1994) Emplacement and preservation of verte brates in caves and fissures Zoological Journal of the Linnean Society 112: 261 283 Simms MJ (2004) Tortoises and hares: Dissolution, erosion and isostasy in landscape evolution Earth Surface Pro cesses and Landforms 29: 477 494 Waltham AC and Fookes PG (2003) Engineering classi fication of karst ground conditions Quarterly Journal of Engineering Geology and Hydrogeology 36: 101 118 Zhang Z (1980) Karst types in China GeoJournal 4: 541 570 Landslides S F Burns, Portland State University, Portland, OR, USA ß 2005, Elsevier Ltd All Rights Reserved Introduction Landslides are a major form of geohazard that cause millions of dollars of damage and many deaths each year They result from the movement of masses of rock, earth, and debris down a slope under the influence of gravity They can occur at all scales, from a few metres across to several kilometres, and at all rates, from metres per year to metres per second The term landslide is really a misnomer because the material can move not only by sliding, but also by flowing and/or falling Landslides are important superficial processes for geomorphology, moving sediment down the slope where water in streams can eventually carry it away They are generally triggered by water, but sometimes earthquakes and even volcanic eruptions can lead to landsliding On land the water comes mainly from heavy and persistent rainfall but also can come from rapid snowmelt Submarine landslides may be triggered by cyclic wave loading as well as by earthquakes, and frequently follow marine trangressions Possibly the largest landslide on land occurred some 10 000 years ago in south-western Iran Called the Saidmarreh Landslide, a mass of limestone 15 km long, km wide, and 300 m thick slid off the underlying marl bedrock and travelled a distance of 18 km while dropping only 1000 m One of the largest underwater slides has been described to have