St James' Pit is a geological Site of Special Scientific Interest in Norwich in Norfolk, England. It is a Geological Conservation Review site within Mousehold Heath, which is a Local Nature Reserve.
This site has been designated because of its jaw and vertebra fossils of Liodon and Mosasaurus, which were two genera of mosasaurs, large marine reptiles dating to the Upper Cretaceous (Campanian-Maastrichtian).
All land within St James' Pit SSSI is owned by the local authority.