Explain the tree types of stress on rocks - compression, tension, shearing. How do they change the earth's surface? What type of plate boundary do most mountain ranges on landform?
There are three main types of stress that can act on rocks: compression, tension, and shearing.
1. Compression: Compression stress occurs when rocks are squeezed or pressed together. This can happen when two tectonic plates collide or converge. The rocks experience a compressive force that can cause them to buckle, fold, or fracture. Compression is responsible for the formation of mountain ranges and the uplift of large regions of the Earth's surface. For example, the Himalayas in Asia formed due to the compression between the Indian and Eurasian plates.
2. Tension: Tension stress occurs when rocks are pulled apart or stretched. This can occur at divergent plate boundaries, where two plates are moving away from each other. Tension causes rocks to elongate and thin, resulting in the formation of rift valleys and the creation of new oceanic crust. The Mid-Atlantic Ridge is an example of a divergent boundary where tension stress is causing the seafloor to spread apart.
3. Shearing: Shearing stress occurs when rocks are pushed in opposite directions along parallel planes. This type of stress often occurs at transform plate boundaries, where two plates slide past each other horizontally. Shearing causes rocks to break and slip along faults. This motion can lead to earthquakes and the formation of fault zones. The San Andreas Fault in California is an example of a transform boundary where shearing stress is causing the movement of the Pacific Plate relative to the North American Plate.
These different types of stress can change the Earth's surface in various ways. Compression can result in the uplift and folding of rocks, leading to the formation of mountains and mountain ranges. Tension can cause the stretching and thinning of the Earth's crust, resulting in the formation of rift valleys and the creation of new oceanic crust. Shearing can cause rocks to break and slip along faults, resulting in earthquakes and the formation of fault zones.
Most mountain ranges on landform at convergent plate boundaries where compression stress is dominant. These plate boundaries involve the collision or subduction of tectonic plates, leading to the compression and uplift of rocks. The collision of the Indian and Eurasian plates, for example, has formed the Himalayas. However, it is important to note that some mountain ranges, such as those formed at divergent plate boundaries, are mainly a result of tensional forces.