Slade Brook Travertine Dams

This remarkable series of dams (at least 60) occurs over nearly half a mile of Slade Brook. They completely dam the stream, which is from 3 to 30 ft wide, and range from about 1 to 18 inches in height, with an average of about a foot. Such dams are formed when spring water, near-saturated in lime, runs over obstructions in the stream bed, when loss of dissolved carbon dioxide results in deposition of travertine (a porous, friable type of limestone). Development of dams may well have been initiated by water running over accumulations of twigs and branches across the stream. The dams are colonised by various species of moss and algae, which become encrusted by travertine as the dams build up, and they have considerable conservation value. Most of the water in the stream is discharged from a large spring, which emerges from the Carboniferous Limestone bedrock near the head of the valley. The Slade Brook dams are possibly the best example of such structures in the country. On no account should they be touched, as they are easily damaged.