Cambridge Greensand
The Cambridge Greensand is a thin layer of rock in England that formed about 100 million years ago, in the early Cenomanian period. It sits between the Gault Formation (below) and the Chalk Group (above) near Cambridgeshire and is the lowest bed of the West Melbury Marly Chalk Formation. The layer is only about 0.1 to 1 meter thick. Its main rock type is glauconitic marl, often described as chalk mud, which contains many small fossils such as ostracods, coccoliths, and forams. At its base there is a concentration of phosphatic nodules and bones. It is a remanié deposit, meaning it includes fossils that were reworked from older rocks, including those of late Albian age such as dinosaurs and pterosaurs.
This page was last edited on 2 February 2026, at 11:24 (CET).