Sunningdale Soil Conditions

This page is principally aimed at new plot holders.

Geology & Soil

The most well-known geological formation in the Thames Valley area is London Clay. However, there is a stretch of land roughly centred on Bagshot, which is approximately 25 miles wide (east to west) and 15 miles from north to south, where the London Clay is covered by layers of sand that were put down between 58 million and 43 million years ago during the Palaeogene era. Three strata are currently identified: Bagshot Formation (the oldest) is dominated by orange and pale yellow fine-grained sand, its depth varying widely with 40 metres in the Bagshot-Chertsey area but only 7 metres in Ascot; Bracklesham Beds containing alternate layers of sand and clay are mainly found in the Chobham, Crowthorne and Farnborough areas; and Barton Beds containing yellowish brown fine-grained sand with an impersistent layer of flint and pebbles at the base are mainly limited to Chobham and Bagshot.

If you are interested in this subject there is a very useful and readable article on the geology of nearby Chobham. Also, Geology and Soils (pdf format) by Michael J. Crawley provides an 8 page summary on the geology of Berkshire. A full explanation of local geology can be found in British Geological Survey: London and the Thames Valley (4th edition), compiled by M.G. Sumbler (an HMSO publication).

Although there are slight fluctuations from plot to plot, the soil on the Sunningdale site is generally light and sandy. The advantages are that it is relatively easy to work and free draining; the disadvantage is that it can dry out quickly. In very dry periods, such as July 2006, the soil becomes very fine and it can take a reasonable amount of rain to “re-hydrate” it. The soil tends to be marginally on the acidic side of the ph divide. One final point of note is that the land is quite stony, which means that some extra work can be required to remove the stones if long straight root crops are required, particularly parsnips.

There are many underground streams in the local area; a number of properties on Church Road used to have wells in their back gardens. In wet winters some plots can become unworkable for periods of time although the sandy nature of the soil means that periods of forced inactivity are seldom lengthy. Some improvements were made by the Parish Council in the early 1990s to limit the amount of water run-off from the school and the car park to the plots by running a drain down the main path to the ditch. The areas that suffer from water run-off are: some adjacent plots to the school playing field; plots in a direct line from the car parks; and some plots that are in a direct line to the three large properties on Church Road.