1) An excavated trench, a ditch, serving in conjunction with a hedge or wall as a boundary, whether as a field enclosure or part of the major defences of a town, castle or camp.
It was also a water channel, either a free-flowing stream or a man-made drain: 1437 ‘The jurors say that the tenants who are held liable to cleanse the water-courses at Meanlandike, Morehouseloyndikes, etc ... have not cleansed them’, Methley. It is a very common place-name element but remained in use as a vocabulary item and came to describe the ditch, the earth thrown up, and the hedge on the bank: 1599 and of the east parte it is devided from the Moore and Common there ... with A Castne quicksett dyke, North Bierley
1609 The Inwarren new repared great dyke was throwen downe all on one nyght ... my sister ... have led thether garcell to hedge it with, Brandsby.
2) In mining contexts this was another word for a fault, a fold in the strata or an intrusion into the vein of coal.
It occurred in Westmorland in 1709, in the sense of vein, and in Scotland as an intrusion in 1805. In Colsterdale, it is recorded several times, e.g. 1702 we have cut a dike which throws the coal down about 3 yards. In Beeston the north side of the dike or horse was referred to in 1787.