The Wren's Nest National Nature Reserve, situated in the West Midlands, UK, is well known for its exposures of Silurian (Wenlock and Ludlow Series) carbonates. The Wren’s Nest was first recognised as a nature reserve in 1965, and in 2020 it became recognised as part of the part of the Black Country Unesco Geopark. The area has significant geological importance due to the superb preservation of its fossils, with more than 700 macro fossil species identified (including brachiopods, bivalves,corals, crinoids, trilobites, gastropods, cephalopods and bryozoans), and is particularly well known for the trilobite Calymene blumenbachii, locally known as the “Dudley Bug”.
The Wren’s Nest Hill forms a large elongated N-S anticlinal dome structure faulted along is main axis by the Wrens Nest Fault, with the structure forming in the Late Carboniferous as a result of the Variscan Orogeny.
The nature reserve also has an extensive industrial heritage with the limestone being mined since the 1700’s for building stones, lime, fertilizer and during the industrial revolution as a flux for iron smelting, with abundant coal being available locally from the surrounding coal measures. An extensive network of mines and tunnels exists, with Dark Cavern being the largest man-made cavern in the UK. These mines are linked together by a series of underground canals which in turn join the national canal network.
With the underground workings closed off to the public for safety reasons this field tour is constructed using surface data only and attempts to reconstruct as much as possible through information from the archives.