Strip mining is the practice of mining a seam of mineral ore by first removing all of the soil and rock that lies on top of it (the overburden). It is similar to open-pit mining in many regards. Strip mining is also used to extract the oil-impregnated sand in the Athabasca Tar Sands.
Strip mining is only practical when the ore body to be excavated is relatively near the surface. Since colossal quantities of material often need to be removed, the excavating machinery used in strip mining is often among the largest such equipment ever constructed; drag line excavators and bucket wheel excavators are common examples.