There are five main types of mountains: volcanic, fold, plateau, fault-block, and dome. A more detailed classification useful on a local scale predates
plate tectonics and adds to these categories.[6]
Movements of tectonic plates create
volcanoes along the plate boundaries, which erupt and form mountains. A volcanic arc system is a series of volcanoes that form near a
subduction zone where the crust of a sinking
oceanic plate melts and drags water down with the subducting crust.[9]
Most volcanoes occur in a band encircling the Pacific Ocean (the
Pacific Ring of Fire), and in another that extends from the Mediterranean across Asia to join the Pacific band in the Indonesian Archipelago. The most important types of volcanic mountain are composite cones or stratovolcanoes and shield volcanoes.[10][11]
A shield volcano has a gently sloping cone because of the low viscosity of the emitted material, primarily
basalt.
Mauna Loa is the classic example, with a slope of 4°-6°. (The relation between slope and viscosity falls under the topic of
angle of repose.[12]) A composite volcano or stratovolcano has a more steeply rising cone (33°-40°),[13] because of the higher viscosity of the emitted material, and
eruptions are more violent and less frequent than for shield volcanoes. Examples include
Vesuvius,
Kilimanjaro,
Mount Fuji,
Mount Shasta,
Mount Hood and
Mount Rainier.[14]
When
plates collide or undergo
subduction (that is, ride one over another), the plates tend to buckle and
fold, forming mountains. Most of the major continental mountain ranges are associated with thrusting and folding or
orogenesis. Examples are the
Balkan Mountains, the
Jura and the
Zagros mountains.[15]
Block mountains
When a
fault block is raised or tilted, a block mountain can result.[17] Higher blocks are called horsts, and troughs are called grabens. A spreading apart of the surface causes tensional forces. When the tensional forces are strong enough to cause a plate to split apart, it does so such that a center block drops down relative to its flanking blocks.
An example is the
Sierra Nevada range, where
delamination created a block 650 km long and 80 km wide that consists of many individual portions tipped gently west, with east facing slips rising abruptly to produce the highest mountain front in the continental United States.[18][19]
Unlike orogenic mountains there is no widely accepted
geophysical model that explains elevated passive
continental margins such as the
Scandinavian Mountains, eastern
Greenland, the
Brazilian Highlands, or Australia's
Great Dividing Range.[23][24]
Different elevated passive continental margins most likely share the same mechanism of uplift. This mechanism is possibly related to far-field stresses in Earth's
lithosphere. According to this view elevated passive margins can be likened to giant
anticlinal lithospheric folds, where folding is caused by horizontal compression acting on a thin to thick crust transition zone (as are all passive margins).[25][26]
Hotspots are supplied by a
magma source in the
Earth's mantle called a
mantle plume. Although originally attributed to a melting of subducted oceanic crust, recent evidence belies this connection.[27] The mechanism for plume formation remains a research topic.
Fault blocks
Several movements of the Earth's crust that lead to mountains are associated with
faults. These movements actually are amenable to analysis that can predict, for example, the height of a raised block and the width of an intervening rift between blocks using the
rheology of the layers and the forces of
isostasy. Early bent plate models predicting fractures and fault movements have evolved into today's kinematic and flexural models.[28][29]
^"Geosynclinal Theory". publish.illinois.edu. University of Illinois at Urbana-Champaign. Retrieved March 8, 2018. The major mountain-building idea that was supported from the 19th century and into the 20th is the geosynclinal theory.
^Мичев (Michev), Николай (Nikolay); Михайлов (Mihaylov), Цветко (Tsvetko); Вапцаров (Vaptsarov), Иван (Ivan); Кираджиев (Kiradzhiev), Светлин (Svetlin) (1980). Географски речник на България [Geographic Dictionary of Bulgaria] (in Bulgarian). Sofia: Наука и култура (Nauka i kultura). p. 368.
^Димитрова (Dimitrova), Людмила (Lyudmila) (2004). Национален парк "Пирин". План за управление [Pirin National Park. Management Plan] (in Bulgarian). и колектив. Sofia:
Ministry of Environment and Water, Bulgarian Foundation "Biodiversity". p. 53.
^Дончев (Donchev), Дончо (Doncho); Каракашев (Karakashev), Христо (Hristo) (2004). Теми по физическа и социално-икономическа география на България [Topics on Physical and Social-Economic Geography of Bulgaria] (in Bulgarian). Sofia: Ciela. pp. 128–129.
ISBN954-649-717-7.