The chalk or malmstone available on the Sinodun Hills is not resistant to weathering.
In the absence of a good locally-available building stone, local buildings were often built of cob. (a compacted mixture of clayey soil and straw).
Examples include a 12th century house found buried under one of the ramparts of Wallingford Castle, and a street of such buildings at St. Thomas' Street in 13th century Oxford. Walls built of this material still survive at Dorchester and Brightwell.
Timber Framed buildings
Other local buildings tended to be timber framed, often with a thatched roof. The Cruck Cottage in Long Wittenham is believed to be up to 800 years old, the oldest house in South Oxfordshire.
Barns at Hill Farm, built in the mid 19th century, used timber frames (some of the wood appears to have been recycled from older buildings), and originally were roofed with thatch.
The church at Long Wittenham, started in 1120, used stone from Caen in France. Stone for the church at North Moreton probably came from the Middle Jurassic oolite to the Northwest of Oxford.
Lime could be had from local pits on Sinodun hillside. Sand was dug from pits at Slade End on the road to Wallingford.
As transportation improved, more material could be brought from outside. Bricks became used for chimneys but were expensive and were re-used when possible. When a brick hunting lodge (the Round House in Church Meadow built in 1788) was demolished around 1838 the bricks were used to build the 'House with the Crooked Chimney' in Little Wittenham.
A source of bricks could have been the brickworks on the river bank at Culham which used local Gault Clay.
