Winterbourne Chalk Pit is a 0.05-hectare (0.12-acre) geological Site of Special Scientific Interest west of Winterbourne in Berkshire.

[1][2] It is a Geological Conservation Review site.

[4] The chalk sediments date to the late Cretaceous period, about 80 million years ago.

[4] The pit is the only known area containing rocks of this age in the western part of the London Basin.

[5] The site is private land with no public access.