Geology
Geology
The geology of the area at Nosterfield Quarry is made up of a combination of materials, mainly sands and gravels together with clays and silts, which were deposited by the action of rivers such as the Ure.
The main bulk of sands and gravels, which is currently being worked at the quarry, was deposited by river systems (known as fluvio-glacial systems) and were active during the last ice age.
These are high quality sands and gravels, which were deposited by a river system far greater in size than the current River Ure, hence their extent.
Current operations
Sand and gravel at Nosterfield Quarry is worked from above and below the natural water table in a series of phases.
The sequence of operations is as follows.
Top soil and sub soil removal:
To prepare a working area or phase for extraction, both the topsoil and the sub soil layers must be carefully removed and stored in separate stockpiles for future restoration. During these stripping operations, a professional archaeologist watches as an excavator, fitted with a toothless bucket, carefully scrapes off several centimetres of soil at a time. If the archaeologist sees anything which requires further investigation, the machine is stopped and the feature is marked with a pin flag before the machine is allowed to continue.
After each pass, the archaeologist checks the features marked by the flags and if any require further investigation, other archaeologists are brought in to carefully excavate, record and preserve the artefacts or features, which have been discovered.
This process continues across the whole of the new phase, until the supervising archaeologist is satisfied that the area has been cleared and all relevant archaeological material has been identified and removed. Only then will the phase be handed over to the quarry so that excavation can commence.
Dry working:
Following removal of the soils, an excavator is used to load sand and gravel into a dump truck, to be transported to the processing plant. This extraction method continues until the natural water table is reached, at which point a dredger is used to extract material from beneath the water table.
Wet working:
Sand, gravel and water is sucked up from below the water table by the dredger and is pumped along a pipeline to a dewatering wheel, which removes the excess water from the material, together with the fine, silty clays contained within the deposit.
The material is then transported to the plant by field conveyor, where it is washed, crushed if necessary and sorted into various products and sizes.
Nosterfield Quarry produces a range of different sized gravels together with good quality sands, which are used mainly for the manufacture of concrete.
