Drift mine
From Conservapedia
A drift mine is a type of coal mine that is driven horizontally into coal that is exposed or accessible in a hillside.
In a hydraulic mine, high-pressure water jets break the coal from a steeply inclined, thick coal bed that would be difficult to mine with the usual underground methods. The coal is then transported to the surface by a system of flumes or by pipeline.
Although currently not in commercial use in the United States, hydraulic mining is used in western Canada.
