Chipping Norton Limestone

Middle Jurassic (Bathonian)

Lithology
Limestone, off-white to pale brown fine- to medium-grained ooidal and coated peloidal grainstone, with common fine burrows, medium- to coarse-grained shell debris and flakes of greenish grey mudstone and dark lignite and minor amounts of fine-grained sand. Thick-bedded and cross-bedded or massive, weathering to flaggy or platy. Thin shell-detrital and ooidal marl and mudstone intercalations in places. Becoming very sandy eastward ("Swerford Beds" facies). Locally a mudstone bed ("Roundhill Clay" of Richardson, L, 1929) up to c.1m thick occurs at the base.

Upper Boundary
Rapid passage upwards into mudstone-dominated Fuller's Earth Formation or Sharp's Hill Formation.

Lower Boundary
Conformable/non-sequential on fine- to coarse-grained ooidal and peloidal limestone, locally ironshot, of Clypeus Grit Member.

Representative Sites
Hornsleasow Quarry
Newpark Quarry

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