Carn Brea

Carn Brea is a granite pluton between Camborne and Redruth. We visit with Year 10 GCSE geologists for their first field trip. Click here for a map showing the locations that we visit.

Starting at the Basset Monument, we examine the large blocks of the granite tor, which show vertical cooling joints, horizontal pressure-release joints and a minor microgranite vein. Pupils describe the texture of the granite, the microgranite and also measure the orientation of the vein and approximate size of the blocks.

Some upper surfaces of the blocks show weathering pits that the pupils measure and describe. We examine the breakdown products of the granite on the floor of the footpath, as well as clitter blocks, which slipped down-slope from the top of the tor by solifluction during the last glaciation, when this area experienced periglacial conditions. Finally, there is a balanced "logan rock" and another microgranite vein at the furthest point