Definition: A man-made watercourse, or makeshift aqueduct, often an artificial channel which supplies water to a watermill or its mill pond, collecting water from upstream of the mill so that the natural level of the driving water is above the level of the stream at the mill. Alternatively to may deliver water for mineral washing and concentration, irrigation or to a dye works.
Definition: A depression caused by erosion by water or ice. Low-lying land bordered by higher ground; especially elongate, relatively large gently sloping depressions of the Earth's surface, commonly situated between two mountains or between ranges of hills or mountains, and often containing a stream with an outlet.