A Site Report

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.

A section through the Greenmoor Rock

After dead vegetation from the top lift had been removed, only the uppermost section of relatively solid rock, with flaggy beds, could be seen, with the overlying material being made up of soil, waste rock and man made items.

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

The spur of rock, the most prominent feature of the RIGS was found to be unstable and large blocks of stone were taken down during cleaning work. At the back of the spur, a wide joint has been infilled with loose breccia and finer material - also weathered to clay.

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. 

The Green Moor Quarry RIGS - after cleaning