The zone between the core and the crust of the Earth is called the mantle. The mantle is a thick layer of rock that makes up about 84% of the Earth's volume. It is divided into two main layers: the upper mantle and the lower mantle. The upper mantle is more rigid and solid, while the lower mantle is more fluid and molten. The mantle is responsible for many of the Earth's geological processes, such as plate tectonics, earthquakes, and volcanoes.