Geological Conservation Review site.
Area: 2.2 hectares.
Description and Reasons for Notification:
The long quarry face exposes about a third of the 120 m thick Ryecroft greenstone. This is typical of the more massive alkali dolerite sills in the area and is intruded into Lower Carboniferous culm argillites. This particular example illustrates internal primary lithological differentiation, as well as cryptic mineralogical variation, and relative to other Carboniferous sills has been chemically and petrographically studied in some detail. In particular the sill is characterised by the presence of large, elongate, early apatite crystals.