Where does malton rock come from?

Answer 1

The earth is made mostly of rock. Deep under the surface this rock is still hot after the creation of the planet.

This heat causes the rock to be 'liquid' (although it's very very thick and flows very slowly) The heat also causes the rock to churn like hot water in a pan. (a process called 'mantle convection'

Where the earth's crust is thin, the churning can force the rock through cracks in the crust, resulting in a volcano. When this happens, the drop in pressure can allow the hot rock to become truly liquid, this is the lava/molten rock we see flowing down the side of volcanoes.