👉 A colliery, also known as a pit mine or a coal mine, is an underground mine used to extract coal from the earth. It consists of several tunnels leading down into the earth and through walls made of rock and sand. The miners work in these tunnels by using ladders, ropes, and other means of transportation. The colliery typically has multiple levels of tunnels, each with its own entrance and exit, as well as a large pit that is dug out over time to store