[1] It is of Thanetian (Upper Paleocene) age.

It lies unconformably on the Thanet Formation for most of its outcrop, but in the west it lies directly on Chalk Group.

It forms the lowermost part of the Lambeth Group.

The type section is at Lower Upnor Pit, north Kent.

The formation has provided fossils of the eutherian mammal Arctocyonides arenae.