Whitby Mudstone

Early Jurassic (Toarcian)

Lithology
Medium and dark grey fossiliferous mudstone and siltstone, laminated and bituminous in part, with thin siltstone or silty mudstone beds and rare fine-grained calcareous sandstone beds; dense, smooth argillaceous limestone nodules very common at some horizons; phosphatic nodules at some levels. Nodular and fossiliferous limestones occur at the base in some areas.

Upper Boundary
Arbitrary boundary in transition to sandy sediments of the Bridport Sand Formation.

Lower Boundary
At base of mudstone overlying ironstone of the Marlstone Rock Formation.

Representative Sites
Robinswood Hill

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