Area: 4.8 hectares.
A new site, listed as of national importance in the Geological Conservation Review, under the name of Tater-Du. Within an Area of Outstanding Natural Beauty.
Description and Reasons for Notification:
This site comprises a partially faulted roof pendant of metabasic rocks within the aureole of the Land’s End Granite (which is here at a shallow depth and reaches the surface at both ends of the site). The contact between the granite and the metabasic country-rock is excellently exposed at Zawn Gamper. The metabasic rocks are submarine pillow lavas, subsequently deformed during the Variscan orogeny and thermally metamorphosed during later granite intrusion. The pillow lavas are strongly deformed but preserve identifiable relict textures and lithological contacts which allow their original identity to be determined. A strong mineral foliation is superimposed on the metabasic lavas, as a result of Variscan regional deformation. Contact metamorphism then altered the country-rock into a gradational aureole of amphibole-bearing hornfels. At this stage, the regional foliation promoted through-movement of fluids related to the granite, giving rise to the development of metasomatic mineral assemblages in the aureole.
This site is of national significance because it provides unique evidence of the geological history of southwest England during the Variscan orogeny, in particular because of the occurrence of pillow lavas. The site is also important for the rare assemblage of minerals associated with granite metasomatism of metabasic rocks.