Continental crust typically subducts below oceanic crust. a. True b. False
The correct answer and explanation is :
Correct Answer: b. False
Explanation:
Subduction is a geological process where one tectonic plate moves beneath another and sinks into the mantle due to gravitational forces. This primarily occurs at convergent boundaries where an oceanic plate collides with either another oceanic plate or a continental plate.
Oceanic crust is denser (about 3.0 g/cm³) than continental crust (about 2.7 g/cm³), which makes it more likely to subduct when the two collide. The oceanic crust is primarily composed of basalt, a dense and heavy rock, while the continental crust is mostly made of less dense rocks such as granite. Because of this density difference, oceanic crust is forced downward into the mantle, forming deep-sea trenches and volcanic arcs.
Continental crust, on the other hand, is less dense and more buoyant, meaning it does not subduct easily. Instead of sinking, when two continental plates collide, they tend to crumple and form large mountain ranges, such as the Himalayas, which were created by the collision of the Indian and Eurasian plates.
An example of oceanic crust subduction can be seen at the Peru-Chile Trench, where the dense Nazca Plate (oceanic) subducts beneath the South American Plate (continental), leading to the formation of the Andes Mountains and volcanic activity along the continent’s edge.
In contrast, when oceanic and continental plates meet, the oceanic plate always subducts due to its higher density. This makes the statement “Continental crust typically subducts below oceanic crust” false since it is actually the oceanic crust that subducts beneath the continental crust.