Most of Treloyan Downs and Cock Hill was probably heathland in medieval times. This would have created ideal conditions for heathland flora and fauna; gorse would have been particularly favoured for fuel.
There was significant tin and copper mining activity in the woods, the latter going back at least as as far as the Tudor period (16th Century). Wheal King and St.Aubyn Tregenna mines were worked here in the early 19th century. There is still evidence of this activity in the form of adits, shafts and old spoil heaps. The woods are believed to have been managed as a woodland pasture (groups of trees interspersed with grassland) before the gaps were planted up to form a continuous woodland in the 19th Century. Many of the mature beech and hornbeam trees show signs of having been cut (coppiced or pollarded), and would have provided valuable timber for a wide range of uses.
Mining also took place on the lower slopes of Trelyon Downs, with a number of shafts known as Trelyon Consols. Thanks to recent Rhododendron clearance, the site of a former reservoir is now clearly visible in this area. Local sources have described how several decades ago it had been grassed over and used as a cricket pitch, before becoming colonised by dense Rhododendron. Today it is again an open area containing only a few native trees and it was ideal as the venue for the volunteer group's open day in the summer of 2008.
Granite was quarried on Cock Hill up until the early 20th Century, used as a building stone in St.Ives and elsewhere.
As the Rhododendron has been cleared, other evidence of the site's past has been gradually revealed, including old stone walls, marker stones engraved with lettering or numbers and also granite blocks showing drill holes where they were split during the quarrying activity.
The Steeple was built in 1782 as a mausoleum for the Customs Officer John Knill, though in fact he wasn't buried there. As well as leaving us the monument itself, Knill has kept his memory alive by instigating a curious community ceremony which takes place there every 5 years (see separate section under "About the Reserve").