Ironstone nodules found at the Green Moor Quarry RIGS |
A condition for the planning permission to
develop Stoneway Manor was that, once the Green Moor Quarry RIGS was cleaned, a
report on the geology would be made, along with a systematic photographic record of the exposed rock
face.
In the old quarries that I had seen around
Green Moor, there were exposures of relatively thick beds of sandstone, once
capable of supplying very large,slabs of paving stone and I envisaged that
the cleaned quarry face would reveal rocks with the same character.
Once the cleaning started, it was soon
obvious that the Greenmoor Rock here was full of oblique fractures and sections
of rock parallel to the quarry face, 50 – 300 mm wide, were becoming detached.
Most of the rock that had fallen down from the quarry face was, at best, only suitable for dry stone walling, except for one large piece of rock, which one of the general workers on site moved by himself from the quarry face to the back of a small van – to everyone's amusement.
Most of the rock that had fallen down from the quarry face was, at best, only suitable for dry stone walling, except for one large piece of rock, which one of the general workers on site moved by himself from the quarry face to the back of a small van – to everyone's amusement.
A section through the Greenmoor Rock |
Here,
natural weathering processes have opened up beds, joints and fractures in the
rock and these have been deeply penetrated and further disrupted by the roots
of brambles, ferns and other invasive species.
Lower
down, the weathered sandstone passes into more massive blocks and, except for
fine partings of silt that are weathered to yellow clay, with occasional
ferruginous beds and associated nodules, most of the exposed rock has a similar
character.
Details from the cleaned Green Moor Quarry RIGS |
Especially
where soil and weathered rock had accumulated on ledges, the rock was extremely loose and very easily disturbed when cleaned
with a trowel, and it was usually pervaded by fine rootlets.
Although
every attempt was made to leave the quarry face in a safe condition, the
oblique fractures, which are an inherent feature of the Greenmoor Rock here, constitute
a structural weakness and a decision was made by the geotechnical engineer to apply
rock netting to the entire length of the old Green Moor Quarry face.
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