Access to coal deposits for underground mines is provided by drift mining. Drift mining cuts horizontally into a hill. Slope mining is cut at an angle from the valley bottom into the hill where the coal is located. Shaft mining is cut straight down deep into the surface by way of a vertical shaft with an elevator to reach the coal seam. In underground mining, after the initial development has gained access to the coal, one of three methods are commonly used to extract the coal. Room-and-pillar, longwall, or shortwall.