Blackford Glen lies between Blackford Hill and the Braid Hills on the south side of Edinburgh where it forms an eastward extension of the Hermitage of Braid containing the Braid Burn. The glen provides a popular walk for local residents and access to the Agassiz Rock, a feature that provided the Swiss geologist Louis Agassiz (1807-73) with evidence for the action of glaciers on the landscape, the first time this had been noted in Scotland. Agassiz was taken to Blackford by editor and amateur geologist Charles Maclaren (1782 - 1866), and although other interpretations for this particular site have been put forward, Agassiz provided the stimulus for geologists to identify evidence of glacial action throughout Scotland.
Andesite was removed from Blackford Hill Quarry, accessible through the glen, to be used as road metal. The quarry, closed in 1953, is now used as a depot by the City Council Roads Department.