These basalts and dolerites were intruded in a hot ( >1000°C) molten state into strata of the Coal Measures and Etruria Marls late in the Carboniferous period (in Westphalian D times) as a result of major earth movements of the Hercynian mountain building episode that were occurring at this time. The magmas slowly cooled at depth and formed the hard crystalline rock that is locally called today the ‘Rowley Rag’.
Columnar jointing in basalt (Rowley Rag), Prospect Quarry, Rowley, taken in 1926. Courtesy of The Lapworth Museum. Lantern slides - Folder LS6 - Coal and Coalfields.
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Blue Rock Quarries - dewatering ready for landfill. Photo by Peter Oliver 1976.
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Blue Rock Quarries - dewatering ready for landfill. Photo by Peter Oliver 1976.
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Blue Rock Quarries - dewatering ready for landfill. Photo by Peter Oliver 1976.
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Darbys Hill Quarry, off City Road, Oakham, SO 967 897, taken by Peter Parkes in the late 1970s. The igneous dolerite rock known locally as 'Rowley Rag' shows well defined columnar jointing.
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New Dudley Road, SO954891. Dolerite intrusion in contact with coal measure sandstone, Conservation Secretary Colin Mitchell on the left. Photo 1979 by Peter Parkes.
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New Dudley Road, SO954891. Spheroidal weathering. Photo 1979 by Peter Parkes.