Answer:
Something known as magma chambers.
Step-by-step explanation:
A magma chamber is a big blob of melted, liquid rock within the Continental Crust.
The rock under our feet (Continental Crust) is basically solid. At subduction zones, in particular, friction (or other) heat can melt the rock at the base of the Continental Crust, and then blobs of molten rock melt their way upwards into the Continental Crust. That’s a magma chamber.
Sometimes the magma chamber has vents leading up to the open air and the magma erupts as volcanoes. In that case, the magma chamber can empty out and the ground above collapses into it, making a hole called a caldera. But more often, the magma in the magma chamber cools down to form solid rock. Such slow-cooled rock will form crystals as it cools. One form of such crystalline rock is granite; cooled down former magma chambers now solid granite are called plutons or batholiths. Typically they will be several kilometres across, and later erosion may well expose them at the surface.
Thanks,
Eddie