Which term describes a section of the lithosphere that moves over the asthenosphere?

The term that describes a section of the lithosphere that moves over the asthenosphere is "plate." The lithosphere comprises the rigid outer layer of the Earth, which includes both the crust and the upper part of the mantle. The underlying asthenosphere is a semi-fluid layer that allows the rigid plates of the lithosphere to move.

This movement is responsible for various geological processes, including earthquakes and volcanic activity, and it is driven by the heat from the Earth's interior, which causes convection currents in the asthenosphere. As these lithospheric plates shift, they interact at their boundaries, leading to different tectonic activity, such as subduction, rifting, and mountain-building.

Other terms, while related to geological processes, do not capture the concept of a moving section of the lithosphere on the asthenosphere like "plate" does. For example, a fault refers to a fracture in the Earth's crust where blocks of rock have moved relative to one another. A trench is a deep, steep-sided canyon in the ocean floor that forms where one tectonic plate is being subducted under another. A ridge typically refers to an underwater mountain range formed at divergent boundaries where plates are moving apart.