Answer:
The asthenosphere is semi-fluid and always in motion. This movement is caused by the heat in Earth and creates convection currents. Convection currents are circular movements based on temperature and density. The heat from deep inside Earth heats up the semi-fluid particles of the asthenosphere. These particles then become less dense and rise. As they rise to the bottom of the crust, they cool off, become denser, and move back toward the core. Back at the core, their temperature will increase again, causing this circular motion to continue.
Convection currents in the asthenosphere cause movement of Earth's tectonic plates. The crust, though rigid, is broken into a series of tectonic plates that fit together like pieces of a puzzle. The plates float on the semi-fluid asthenosphere and move around in predictable directions. It's like a giant conveyor belt moving molten material from one place to another and causing the plates that float on top to slide to new locations.
Step-by-step explanation: