Fascinating facets of Earth heritage to explore on this Brecks heath.
Zoom in to the Google Map to find the points of interest.
Barnhamcross Common is a classic Brecks heathland that has been the focus of much ecological restoration work in recent years. The key to its wildlife value lies in three soil types found here - each linked with a story of landscape change. It is good place to see Ice Age patterned ground, where varieties of plant life can be linked to variations in subsoil geology. The Common is designated a Site of Special Scientific Interest, particularly for its plant life.
The Common is a heathland SSSI.
Chalk lies near the surface on the higher ground of the Common, covered by a layer of windblown sand. This gives rise to calcareous sandy soils. During the last Ice Age, over 12,000 years ago, frost action churned the subsoil in periglacial conditions, separating it into contrasting bands of chalky and sandy soil on slopes. You can see these on some Google Earth aerial photos, particularly in the 2005 ‘historical imagery’ view. Today, plant-life reflects these contrasts, best seen in May or June on open ground in the south-western part of the Common the area (see map). Another place to see these ‘Breckland stripes’ is Thetford Heath, about 2.5 km (1.5 miles) away to the south-west (grid ref TL844797). These are best viewed from the road.
Contrasting plant life of calcareous and acidic soils. [Artwork courtesy Beverly Curl]
The land east of the A134 road has areas of sandy and gravelly soils (see map). This is an area of river terrace, a former floodplain of the River Little Ouse laid down by meltwater torrents in the last cold period (the Devensian). It has been dug in many places for sand and gravel, leaving hummocky terrain and habitat suitable for plants of well-drained, acidic soils.
Sandy ground with acidic heathland flora.
The Little Ouse has cut into the side of the terrace at the south-eastern end of the Common (see map). You can see flint-rich gravels in this area, where human activity has made scars in the terrace surface.
A exposure of terrace gravels beside the river.
There is a marshy area with peaty soils at the southern end of the Common (see map). It is part of the river’s present-day floodplain. It was probably a permanent area of wet fen in past centuries, before the water levels in the valley were lowered by drainage improvements. Commoners are likely to have extracted peat here for fuel.
A wet area on the Little Ouse floodplain.
There is a shallow dry valley in the centre of the Common (see map). It is underlain by permeable, sandy soils that cannot hold flowing water today, so how was the valley formed? Perhaps at a time when the ground was more solid, perhaps when frozen during the Ice Age, or when groundwater levels were much higher in the underlying chalk, and springs were more active.
A view over the dry valley.
The site is on public access land - see Ordnance Survey Explorer map no.229 ‘Thetford Forest in The Brecks’ (c.TL 864 814). There are two car parks, both with information panels (see map) interpreting the natural and cultural heritage of the Common. Take special care on the A134, as it is a fast, busy road.
A Tomorrow’s Heathland Heritage panel.