__ processes form mountains due to deformation at a plate boundary.
A. Taphrogenic
B. Viscoelastic
C. Orogenic
D. Epeirogenic
The Correct Answer and Explanation is:
The correct answer is C. Orogenic.
Explanation:
Orogenic processes are geological phenomena associated with the formation of mountains, particularly at the boundaries of tectonic plates. These processes occur due to the interaction of the Earth’s lithosphere, which is divided into several tectonic plates that float on the semi-fluid asthenosphere beneath. There are three primary types of plate boundaries: convergent, divergent, and transform. Mountain formation predominantly occurs at convergent boundaries, where two tectonic plates collide.
When two continental plates converge, the collision causes immense stress and pressure, leading to the thickening of the Earth’s crust. This thickening is primarily due to processes such as folding and faulting, which result from the compressive forces acting on the crust. The intense pressure can also lead to metamorphism, transforming existing rock types into new forms. This uplift of the crust over geological time scales results in mountain ranges, exemplified by the Himalayas, which formed from the collision of the Indian and Eurasian plates.
Orogeny is a term that encompasses various mountain-building processes, including subduction (where one tectonic plate is forced under another), continental collision, and volcanic activity. These processes can lead to the formation of a range of mountain types, such as fold mountains, fault-block mountains, and volcanic mountains.
In contrast, the other options listed—taphrogenic, viscoelastic, and epeirogenic—do not specifically refer to the mountain-forming processes. Taphrogenic processes involve subsidence or rifting, viscoelastic refers to material properties of rocks under stress, and epeirogenic processes involve the uplift or subsidence of large land areas without significant folding. Thus, orogenic processes are the definitive geological activities that create mountains through the deformation of the Earth’s crust at plate boundaries.