Monument record MBC45269 - 19th century coprolite workings, Great Firs.

19th century coprolite workings are visible on historic aerial photographs and remote sensing data as earthworks and were mapped as part of the North Buckinghamshire Aerial Investigation and Mapping project (EBC18304). Located about 650 metres W of St Margarets Farm and centred at SP 90106 31760, an irregularly shaped coprolite extraction area covers an area about 33,251 square metres. A bed of phosphatic nodules was discovered in 1873 scattered through about 30 feet of coarse sand, 15-20 feet being red sands, below which the remaining 10 feet were greenish-grey shelly sands. In 1874 work began at The Firs (now Great Firs), two fields belonging to Galleylane Farm for a period of 7 years. The excavation pit is not recorded on the 1881 dated 1st Edition OS map and so it seems likely that work on the site has ceased by that time. When in operations, two horse drawn carts on a tramway led from the coprolite pits downhill to Stoke Hammond Meadow, adjacent to the Grand Junction Canal, and the Aylesbury to Water Eaton Road. The remains of this tramway is visible as a linear earthwork bank up to 6 metres wide leading 450 metres long from the pit aligned WSW-ENE to Galley Lane on aerial photographs taken in the 1940s. The remaining course of the tramway is then visible as pale cropmarks on aerial photographs taken in the 1940s, leading about 753 metres from the W side of Galley Lane to the river above Stoke House Farm. On aerial photographs taken in 2019 and recent remote sensing data, the coprolite working area is just visible as a shallow area of disturbance, but the tramway’s earthwork bank is not visible (1-8).