The ground
River gravel · West Melbury Marly Chalk
Cholsey is mapped on river sand and gravel — a Thames terrace — over soft, marly chalk. Ground like that generally drains well.
Within half a kilometre, to the north and west, the map changes to alluvium and Upper Greensand, so the soil can differ from one side of the village to the other.
Planning
Cholsey Conservation Area · North Wessex Downs (most of the parish)
The village centre is in the Cholsey Conservation Area. There, tree work needs six weeks’ notice to the council (trees under 75 mm across, measured 1.5 m up, are exempt), removing an old fence, wall or gate can need consent, and a shed or garden room at the side of the house needs planning permission.
The centre is just outside the North Wessex Downs National Landscape, but about 64% of the parish is inside it. For addresses inside it, permitted development limits outbuildings more than 20 metres from the house to 10 square metres in total.