Why isn t earth's entire mantle liquid?

The Earth's entire mantle isn't liquid because increased pressure increases the melting point of the rocks, so even though the rocks get hotter, they never get hot enough to reach their melting point. ... It's present in the pore spaces of some rocks and can be bound in the crystal structure of some minerals. read more

Earths mantle isn't liquid since pressure increased melting point of rocks. Those rocks never reach their melting point. read more

The mantle isn't 100% liquid because magma solidifies near the crust and becomes plastic in texture and not fluid but eventually cools down to form the lithosphere. read more