Forty miles deep in the earth is the edge of the outer crust of the earth,and there it is so hot that instead of hard rock there is material much like the hot lava that a volcano erupts.

• 地表面下40英里深，是地球外壳的边缘，此处非常之热，如同火山喷出的岩浆般的物质替代了坚硬的岩石。