Sea Point contact zone
From Wikipedia, the free encyclopedia
The Sea Point contact zone is a geologic boundary where the Malmesbury Group was intruded by molten granite, and can be seen at Sea Point.[1] It extends over a width of about 150 meters.[2] The Sea Point contact was first described in 1818 by the British naturalist Clark Abel.[2][3] It was later made famous by Charles Darwin during his voyage of scientific discovery on H.M.S. Beagle.[2][3][4]
Here, slivers of dark coloured Malmesbury rocks, altered by intense heat are intermingled and folded with the pale coloured intrusive granite to form a complex mixed rock. Large feldspar crystals occur in both the granite and dark hornfels layers.[3]
Though initially intruded at great depth, prolonged erosion eventually exposed the granite at the surface and it and what remains of the similarly eroded Malmesbury group now form a basement upon which younger sedimentary rocks of the Table Mountain Group were deposited.[5]
The Sea Point contact zone was declared a national monument in 1953.[2]
