Here's why:
* It's not entirely liquid: The asthenosphere is a part of the upper mantle, but it's not completely molten like magma. It's more like a very viscous fluid, capable of flowing over long periods.
* It's plastic-like: Think of it as a very thick, hot syrup. It's strong enough to support the weight of the tectonic plates but weak enough to deform under pressure.
* It allows for movement: This semi-liquid nature allows the tectonic plates to move around on the Earth's surface, causing earthquakes, volcanic eruptions, and mountain building.
Let me know if you'd like more details about the asthenosphere!
