Castle Mill basin, Wren's Nest tunnel portal, Dudley canal

Image: © Rudi Winter Taken: 8 Jun 2014

The Dudley tunnel ends in Castle Mill Basin, which originally was an underground limestone mine, has subsequently been widened to allow canal boats to turn around and is now a steep-sided hole in Castle Hill. From here the main canal leaves through the shorter Tipton tunnel (behind camera), while a branch tunnel leads west to the limestone mines inside Wren's Nest. This branch tunnel is now blocked off by a dam as can be seen in this photograph. Castle Mill basin is named after Castle Mill works, the buildings situated atop Tipton tunnel. Castle Hill and nearby Wren's Nest are anticlines of Silurian limestone layers protruding from the surrounding Carboniferous coal beds. Both the limestone and the coal were quarried from the beginning of the industrial revolution and used in the iron smelting industry of the West Midlands of England. Mining finally ceased in 1920. The Dudley canal was completed in 1791, running in a tunnel under Castle Hill for nearly 3km in a SSW direction. Several branch canals were built around the same time to access the limestone seams in the Castle Hill anticline, which run roughly SSE. In addition, there is a westerly branch leading to Wren's Nest. Multiple caverns have been excavated inside Castle Hill, some of which up to 800m in length. Many of the caverns have had roof collapses and rock falls and have since been backfilled. However, some are still accessible by boat through the original tunnels and a few new link tunnels built in the 1980s to enable the Dudley Canal Trust to run circular tours for visitors to see the mines. A schematic map of the canal system is shown on the Trust's website https://web.archive.org/web/20150101180643/http://www.dudleytunnel.co.uk/mines.html (archive link).

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