dook

A dook is a horizontal or gently inclined roadway driven underground along the natural dip of coal seams or mineral-bearing strata. Rather than cutting across the rock layers at an angle, a dook runs parallel to their slope, allowing miners to follow a coal seam as it descends into the earth. This method contrasts with sinking a shaft vertically or driving a level (which runs roughly horizontal) and offers practical advantages in collieries where seams dip at moderate angles.

The dook is commonly used in British coal mines, particularly where seams dip at 15 to 45 degrees. By following the strata naturally, the dook minimizes the thickness of stone that must be broken through alongside the coal; a roadway cutting across the dip would expose progressively more barren rock. This saves labour and timber support. A dook is wide enough for loaded coal tubs to pass, typically 2.5 to 3 metres wide in the working section, and ventilation ducts or water channels often run alongside.

As coal dips deeper, gravity aids the loaded journey outward, so tubs can be lowered by rope or gravity on gentle grades. Empty tubs return lighter, and in steeper dooks, a system of ropes and pulleys may be rigged. Drainage is critical; water naturally flows along a dipping seam and must be managed to keep the roadway passable. A dook that follows a seam dipping at a steady angle remains in coal long enough for economical extraction, whereas deeper pits may require multiple dooks at different levels to work the same seam as it sinks.

The term reflects practical geology and Welsh and Northern English mining tradition. A dook takes its name from the Dutch and Low German word for a passage or tunnel, entering English mining speech through contact with Flemish and German miners. It remains standard vocabulary in historic mining records and surviving pit documentation, though the technique is now largely historical as deep mines have closed.

Dooks are distinct from gate roads (which connect to roadways) and from slopes or inclines (which are steeper and often mechanically worked). In seam thickness mapping and mine planning, a dook's location and gradient determined how far coal could be extracted before the seam became too deep or too thin to work profitably, making dook placement a key decision in mine design.