Brown earth soils are widespread in Britain, except in highland areas.
Soil organisms, like earthworms, mix the materials together, merging the boundaries between the horizons.
These soils are leached, but not heavily, so the aluminium and iron oxides are dispersed through the soil to give the overall brown colour.
The original vegetation was deciduous forest, resulting in a layer of decaying leaves giving a rich humus.
The deep roots of these trees reached down to the 'B' horizon, unlike with coniferous trees, tapping the nutrient supply and allowing good drainage.