slant

A slant is a mine working driven at an angle to both the dip and strike of a coal seam, typically to gain access to the coal body or to move between different seams at different elevations. Unlike a level (which runs horizontally along the strike) or a rise (which follows the dip upward), a slant cuts diagonally across the geology, making it the most direct route when vertical distance must be covered without sinking a shaft.

The geometry of a slant depends on seam thickness and the angle of inclination needed. In a seam dipping at, say, 20 degrees, a slant driven at 30 to 40 degrees to horizontal will traverse the seam efficiently. The slant's gradient is set before driving begins, and timbering or bolting must account for the roof load acting perpendicular to that incline. Coal extracted along the slant is typically hauled by gravity or by mechanical haulage (rope or chain) rather than relied upon to roll freely.

Slants are often driven in pairs or groups to provide multiple connections between seams or to offer escape routes and ventilation paths. They are distinguished from inclines, which are formally sunk at steeper angles and may be fitted with permanent mechanical haulage infrastructure. The term slant is less formal and may refer to any diagonal working, whereas an incline usually indicates planned, engineered access with fixed equipment.

Safety concerns specific to slants include standing water pooling on the incline floor and poor roof contact along the rising edge, where the coal seam narrows or the roof rock separates. Ventilation in slants can be sluggish if the gradient is shallow, allowing methane or dust to accumulate. Haulage friction and brake wear are also higher on steep slants, making maintenance of hauling gear critical.

The slant's name reflects its appearance and function: it neither rises vertically like a shaft nor runs level like a gallery, but instead slants diagonally through the strata. In coal mining, particularly in Britain and older North American fields, the slant was the workaday alternative to the expense of sinking a shaft when moderate depth and seam separation could be navigated by angled driving.