Carn Marth lies southeast of Redruth and is part of the Carnmenellis granite plateau, the 'Carnmenellis Granite', one of several granite
plutons in Cornwall that make up part of the
Cornubian batholith (see also
Geology of Cornwall). In prehistoric times men settled on the uplands as they had many advantages over the more densely vegetated lowlands. From the late Stone Age they have been natural places of refuge; offering easily defended bases and view points over what was the densely wooded landscape of prehistoric Britain. In early modern times they have been perfect sites to mark victories and celebrations, and to host warning beacons of impending attack such as the feared Spanish invasion of the 1580s. The hill can be seen from the hills of
Bodmin Moor on a clear day, over : the reverse is also true. One can look back, up to the East past St Agnes Beacon to the hills of the Moor,
Rough Tor and
Brown Willy, the highest hill in Cornwall at , Carn Marth being lower at . The Celtic Sea and Bristol Channel to the north and the English Channel to the south are both easily seen. Those with keen sight or binoculars will be able to pick out St Anthony's Light at the entrance to
Carrick Roads with
Pendennis Castle and
Falmouth opposite. Turning further west there is the glint of light on the reservoir at
Stithians, then more hills,
Carnmenellis and
Carn Brea, with views across the
Great Flat Lode and its attendant engine houses making such poignant relics of the great age of mining. ==Ecology==