Gilwern Hill is formed from a series of rock strata of Carboniferous age, each of which dip moderately southwards.

The latter has been extensively quarried around the eastern, northern and western margins of the hill where it is exposed.

[1][2] Virtually the entire hill is designated as open country and so access is therefore available freely to walkers.

A minor road wraps around its southern and western margins whilst a couple of public footpaths and a restricted byway cross the northern and eastern slopes of the hill.

The quarries provide a minor venue for rock climbing.