Mountain range: formation, structure, and significance

In common parlance, a mountain range is understood to be

• a group of more or less connected mountains as a mountain range or group of mountains
• a mountainous geographical region, a mountainous country

The word "mountain", on the other hand, has a regionally different perception. Elevations such as the Wilseder Berg, at only 169 m above sea level the highest point in the vicinity of Lüneburg, would at best be called a hill in Alpine countries. In general, "mountain" denotes a single peak or a ridge line. "Hügelland" stands for accumulations of small elevations, without an exact delimitation being possible.

Geology, on the other hand, refers to the "mountain base" in its definition: the mountain base or rump (when exposed) is the basement. In the younger mountains it is overlain by the overburden, and in the process is often pushed to great depths (as far down as the Moho). "Mountains" in the latter terms already stands in the geological sense as a "rock unit".

In the English language, there is no term for mountains in the sense of a coherent entity: "Mountains" means "mountains" and is thus merely the plural without any concrete attribution.

Highlands - such as Tibet - are not considered mountains because they have little elevation change. In contrast, some areas on a cliff may be considered mountainous despite having little elevation above sea level.

See the EU definition of mountainous areas: classification according to altitude and steepness.

In geology, the term mountains or the technical term orogen is used inconsistently. In the American Press/Siever: General Geology (2008), the term orogen is used for young mountains and contrasted with the terms shield, platform, sedimentary basin, crustal extension zones (areas in which the youngest deformation is due to crustal extension), and large volcanic provinces.

In the sense of geology, mountains are primarily elongated bands of deformed rocks that are formed by lithospheric plates pressing against each other (mainly in the vicinity of two plates, but also far away from them by stress transfer) and thus lead to the formation of mountains mainly by overthrusting of sheared rock covers. The greater the pressure effect of plate tectonics and the longer it lasts, the higher the uplift of the Earth's crust and the more parallel strands bulge to the right and left of the central, oldest area. While these intermontane intermediate ranges often consist of compact, poorly articulated plateaus (such as the highlands of Tibet, the Altiplano, or the Columbia Plateau), the younger marginal ranges are usually more strikingly rugged and clearly demarcate themselves from the surrounding lowlands.

The formation of the mountains is accompanied by changes in the rocks. Typical rocks for mountains are metamorphic rocks such as gneiss, as well as igneous rocks such as granite, both rocks have a high silicon content typical for the continental crust.

Mountain shapes

Mountains can also be classified according to their general geomorphological or orographic shape. Measures for this are the relief energy, dominance and height of the individual peaks and mountain groups:

• Ridge mountains: Linear mountain ranges with pronounced, branched ridge lines (Taunus, Salzburg Slate Alps).
• Kammgebirge: Linear mountain ranges with a single main ridge line (Krkonoše, Bachergebirge in the Alps).
• Chain mountains: Linear mountain ranges with several parallel ridges (Alps, other alpine mountains).
• Kuppengebirge: Mountains with irregularly rising peaks that rise from a common mountain base (Frankenwald, peripheral mountains of the Alps)
• Massif mountains: Clearly closed elevations in relation to the surrounding countryside, which, however, do not show any recognizable main direction of individual mountain ranges (Harz, French Massif Central)
• Plateaugebirge: Mountains where only the base is preserved and there is no ridge line and little summit formation (Swabian Alb)
• rump mountains: mountains of which only the rump remains, elevated hills (Bohemian Massif)
• Shield: An old mountain hull as a tableland, which is no longer recognizable as such (Baltic Shield)
• Inselberg: mountain range that rises abruptly from a plain (Sugar Loaf, Uluru, mid-Swedish inselbergs)

With regard to their formation and internal structure (rock profile), a distinction is made:

• Tectonic mountain range formed by tectonics, i.e. slow movements of rock masses:
• Ceiling mountains are formed by strong lateral thrust without any possibility of escape (Alps)
• Folded mountains due to plastic deformation of rock layers in geosynclinal seas (Swiss Jura)
• Fracture fold mountains, also fracture clod mountains due to folding and fracturing of the blankets (Rocky Mountains)
• by pure fracture tectonics the following forms are formed:
• Block Mountain
• Fracture Mountains
• Schollen Mountains
• Volcanic mountains, which are formed by the "coalescence" of several eruption foci (Vogelsberg, Auvergne), or from a single hard effusive mass (Adamello group).

In a large mountain range, different mountain types can also mix. The complex history of folding and overthrusting of the Alps shows numerous small forms of other mountain types.