Fuller's Earth

Middle Jurassic (Bathonian)

Lithology
Silicate-mudstone, grey, bedded, variably calcareous, grading to lime-mudstone, fossiliferous, with units of thinly interbedded, more or less silici-muddy limestone (including the Fuller's Earth Rock Member, Dodington Ash Rock Member), and well-bedded sandy limestone and calcareous sandstone (including the Eyford Member and Througham Member). Where the Fuller's Earth Rock Member is present, the mudstone beds below and above are termed the Lower Fuller's Earth Member and Upper Fuller's Earth Member respectively, and parts of these may be given local names. The commercial fuller's earth bed occurs in the upper part of the formation in the Bath area.

Upper Boundary
Generally sharp, commonly non-sequential, junction between variably calcareous silicate-mudstone, and limestones of overlying parts of Great Oolite Group, including ooidal and shell-fragmental limestones, of the Chalfield Oolite Formation, Athelstan Oolite Formation, Taynton Limestone Formation, or fine-grained limestone of the Tresham Rock Formation.

Lower Boundary
In the northeast Cotswolds, passage up from fine- to medium-grained ooid-grainstone of the Chipping Norton Limestone Formation (Great Oolite Group) into silicate-mudstone, or (Cotswolds to the English Channel) generally sharp, commonly non-sequential, junction between predominantly coarse-grained peloidal, ooidal and shell-fragmental limestones.

Representative Sites
Huntsmans Quarry
Easter Park Farm Quarry
Tetbury Station and Goods Yard

Information on lithology and boundaries taken from the British Geological Survey Lexicon of Named Rock Units