A small river in East Ayrshire, the Gass Water rises at Gasswater Head, a mile (1.5 km) north of Glenmuirshaw, and flows west and then northwest, becoming the Bellow Water at Welltrees, having completed a course of 5 miles (8 km). Much of the area represents a post-industrial landscape with clay, limestone, ironstone and coal all extracted nearby. A significant Barytes mine operated on the northern bank of the Gass Water in the first half of the 20th C. extracting the mineral to be used as a white pigment in paint, and in the manufacture of paper, porcelain, textiles, leather and linoleum. It was transported at various times by an aerial ropeway and a branch of the railway.