WaltersRail : Powder River Basin: Part One (BNSF)
The coal beds in the Powder River Basin are shaped like half a bowl sliced vertically. A mine starts at the top of the bowl, where coal is near the surface, but as it moves it digs progressively deeper until it reaches the bottom. The overburden (rock and sediment on top of the coal) is loosened by dynamite charges that shake the ground for ...