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| A Permian Bryozoan Reef |
Whilst surveying a wide variety of natural landforms and active and redundant quarries in South Yorkshire, I have seen many ancient bryozoan reefs and, the Yellow Sands Formation excepted, I think that these are the most interesting rocks that can be found in this region.
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| A detail of the Permian reef at North Cliff Quarry |
At North Cliff Quarry, one of these reefs overlies massive
beds of buff coloured, cross bedded, oolitic dolomitic limestone that is full of of small bivalve fossils - often preserved as
moulds - giving the rock a porous texture that distinguishes it from the beds that lie above and below them.
The lower section of the reef mass is partially
brecciated - often with a distinct reddening of the fine grained matrix, which provides
evidence of the influx of muddy sediments similar to those found in the Permian marls.
From paths running along the top of the various quarry
faces, there are also excellent views of the scarp and dip topography of the Coal Measures strata to the west, the limestone
escarpment to the north and the Don Gorge to the east.
Like
so many old quarries, North Cliff Quarry has attracted dirt bike riders and has been a dumping ground for cars. When I last visited the site, in 2007, bottles and cans and miscellaneous rubbish littered the
place; however there was still easy access to most of the rock exposures.
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| A few views at North Cliff Quarry |
