GREENHAM & CROOKHAM COMMONS COMMISSION

Geology

The Common is a high plateau lying between the Kennet and Enborne valleys consisting of Eocene deposits of Bagshot acid sandy clays formation over heavy London clay. This is overlain by plateau gravel deposits from meltwaters resulting from glacier retreat. It is interspersed with alkaline pockets caused by cement contamination from the runway construction and its final removal. This gives an unusual situation of acid and alkaline soils occurring in close proximity.

There are some perched ponds, the largest, known as Taffy's pond, being opposite the golf course. There are pockets in lower areas where ponds lie below water table level can dry out or remain boggy. Others can hold water in dry weather at much reduced volume. There is a new formation of wetlands at the north east side of Crookham common which mostly lie below water table but have been known to dry out in a long period of dry weather.

Wetland landscape 2 years after formation - click to see full size

Wetland landscape 2 years after formation

Drain off from the plateau area forms seepage and springs which have created gullys and waterlogged valleys down the North and South East sides of the common. Alder and a variety of mosses flourish in these areas. Some catchment pools formed in the airfield construction remain but are very silted. The majority of the small bournes is on the South East and South sides and run into the Enborne.

Handpost Gully - click to see full size

Handpost Gully

Further information can be obtained on www.naturalengland.org.uk and search for Berkshire RIGS.

Ecology

Greenham and Crookham Common is a special place with ancient woodlands, flower rich grasslands and the largest continuous tract of lowland heathland in Berkshire. If you were to walk around the common, you would encounter rare and protected plants and animals. You might spot birdlife such as Dartford Warblers, Skylarks, Woodlarks, Song Thrushes, Common Linnets and Willow Tits. There are 28 birds listed recorded here that appear in the Biodiversity Action Plan for the U.K. There are protected species such as the Little Ringed Plover and Lapwing in reasonable numbers. Nightjars are regular visitors in the spring and Nightingales can be heard singing on a summers evening, but their numbers are under threat.

Lapwing. Photo: Greenham Common Trust - click to see full size

Lapwing

Great Crested, Palmate and Smooth Newts can be found in the many ponds and pools and specialist insects like the Grayling and Small Blue butterflies flutter around the gravelly heaths. A project exists to re-introduce the Silver Studded Blue Blutterfly. Green Tiger Beetles and Bog Bush Crickets are common in summer.

Newt - click to see full size

Newt

The grasslands are rich in orchids; you may view the photo pages to see these. The very rare Star Fruit plant was introduced to the Common in 2006 but shortly died back. Other interesting flora are Solomon's Seal and Lily of the Valley, Upright Chickweed, Knotted Clover, Heath Cudweed, Spiked Star of Bethlehem and Mochatel.

The Common is important nationally for its ecology, and as such it is designated as a Site of Special Scientific Interest to provide legal protection. The citation is copied in the Management plan.

Fuller details of the Common's ecology can be seen in the Management Plan at www.westcombe.org.uk.

Information on the S.S.S.I. can be obtained at www.naturalengland.org.uk.

GRAZING AND GORSE CONTROL - A review by Natural England, May 2012.