What is a mountains origin?
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http://www.infoplease.com/encyclopedia/science/mountain-the-origins-mountains.html
The origin of mountains can be explained by the geological processes that shape the Earth's surface. To understand how mountains form, we need to consider two main mechanisms:
1. Plate Tectonics: Mountains are commonly formed at tectonic plate boundaries, where the Earth's lithosphere (crust and upper mantle) is divided into several large sections that float on the underlying semi-fluid asthenosphere. There are three types of plate boundaries:
a. Convergent Boundaries: When two plates collide, one can be forced beneath the other in a process called subduction. The subducted plate gets pushed deeper into the Earth's interior, melting and forming magma. The magma then rises to the surface, creating volcanic mountains. Examples include the Andes in South America and the Cascade Range in North America.
b. Divergent Boundaries: In some areas, plates move apart, allowing magma to rise up and solidify, creating new crust. This process occurs along mid-ocean ridges, where new oceanic crust is formed, and also in continental regions where rift zones develop. The East African Rift Valley is an example of a continental rift zone.
c. Transform Boundaries: Here, two plates slide past each other horizontally. Although not directly responsible for mountain formation, these boundaries can cause intense pressure and deformation, leading to the creation of fault lines and associated mountain ranges. The San Andreas Fault in California is an example of a transform boundary.
2. Uplift and Erosion: Besides plate tectonics, mountains can also form through vertical uplift or the erosion of existing landforms. Uplift occurs when large forces within the Earth push the crust upward, forming mountain ranges. The Himalayas, for instance, were created by the collision of the Indian and Eurasian plates. Erosion, on the other hand, is the wearing away of existing rocks and landforms by natural processes like wind, water, and ice. Over time, the continuous erosion of softer rocks surrounding harder ones can shape mountain ranges and create their distinctive features.
In summary, mountains can originate through plate tectonic interactions, including subduction, spreading, and transform boundaries. Additionally, vertical uplift and erosion can contribute to the formation and shaping of mountains.