The ground
Chalk · river gravel · alluvium
The centre of Purley on Thames is mapped on chalk with nothing over it. Within half a kilometre, river gravel is mapped to the north and south, alluvium to the east towards the Thames, and Head — a mixed hillwash of clay, silt, sand and gravel — to the west.
Chalky soils are very alkaline and often shallow and free-draining, says the RHS, so lime-tolerant planting does best and watering matters in a dry spell. Closer to the river the ground is more mixed, and it can change markedly over a short distance.
Planning
North Wessex Downs · West Berkshire
The village centre sits just outside the North Wessex Downs National Landscape, about 0.4 km from its boundary, but around 64% of the parish lies inside. At addresses there, an outbuilding at the side of the house needs planning permission, and anything built more than 20 metres from the house — sheds, enclosures, even a pool — is capped at 10 square metres in total without planning permission.
No conservation area covers the centre; Mapledurham’s, across the river, is about 0.8 km away. A boundary up to two metres tall, or one metre alongside a road, normally needs no planning permission.