The hot liquid that lies under the Earth's crust is called magma.

Here's a bit more about magma:

* Composition: Magma is a mixture of molten rock, crystals, and dissolved gases.

* Location: It's found beneath the Earth's surface, in the upper mantle and lower crust.

* Temperature: Magma can reach temperatures of over 1,600°F (900°C).

* Movement: Magma can rise towards the surface due to buoyancy and pressure.

* Volcanic Eruptions: When magma reaches the surface, it's called lava and can lead to volcanic eruptions.

Let me know if you have any other questions!