Calderglen Country Park is built around the gorges cut by the Rotten Calder Water, the river that bounds East Kilbride's eastern flank before flowing north to join the Clyde. The park combines what was once two adjoining estates - Calderwood to the north, Torrance to the south - both rich landowner properties whose grand houses are now mostly memory. Torrance House survives: a Category A listed 17th-century mansion that today serves as the park's visitor centre, gift shop and cafe. Calderwood Castle did not survive; what was left of it was demolished in 1951. The park officially opened in 1982, gathering the surviving fragments of two estates into one greenspace that East Kilbride has used as its principal recreation ground ever since. There are 33 hectares of designated woodland, several miles of nature trails, and a series of waterfalls along the Rotten Calder.

The northern part of the park is a Site of Special Scientific Interest, designated for its carboniferous geology. The Rotten Calder has cut through the layered sediments that record the long ago tropical river deltas and shallow seas of the Carboniferous period - the same beds that produced Lanarkshire's coalfields. Along the gorge walls you can read 320 million years of accumulated mud, sand and decayed forest, exposed where modern erosion has carved through them. Waterfalls drop where harder strata resist faster than softer ones. The trails along the western bank are prone to landslips for the same reason: this is geology in slow motion, the gorge still actively reshaping itself. The longest paths run from Flatt in the south to the A725 in the north, threading the riverbank for the full length of the park.

Calderglen has a small zoo - small enough that its meerkats and prairie dogs have appeared in Daily Record human-interest stories about new arrivals. Outdoors you can find owls; indoors, a tropical glasshouse contains reptiles and fish. There is a modern outdoor playground, a tree-lined driveway leading up to Torrance House, and ornamental gardens around the visitor centre. The recreation side of the park is extensive: East Kilbride F.C. plays at the K-Park Training Academy here; East Kilbride RFC has its rugby grounds in the park; East Kilbride Cricket Club, formed in 1962, fields its team here; Torrance House Golf Club opened in 1969 and remains open to public bookings; East Kilbride Lawn Tennis Club runs the tennis facilities. Calderglen is, in effect, the sports infrastructure of a new town as much as it is a country park.

Approach the park from the old entrance lodge and you come up a tree-lined driveway that has the proportions of a private estate, which until 1982 it was. The visitor centre at Torrance House is the gathering point - a 17th-century house with a courtyard now set with picnic tables. From there the trails fan out, west along the banks toward the Calderwood residential district and the buried site of Calderwood Castle, or south through the deeper gorge sections toward Flatt. Snow falls hard on the driveway in winter; in autumn the canopy turns the colour of malt whisky. The Rotten Calder, despite its name, runs clear in the upper reaches - the rotten refers to the river's old reputation for slow drainage in its lower meanders, not to any modern pollution. The waterfalls are real, the geology is genuinely interesting, and Falstaff is still in his garden.