Charmouth Mudstone Formation

Charmouth Mudstone Formation
Stratigraphic range: Lower Sinemurian– Lower Pliensbachian Semicostatum-lowermost Margaritatus 198–188 Ma PreꞒ Ꞓ O S D C P T J K Pg N
Cliffs of the Charmouth Mudstone Formation at Charmouth, Dorset
Type	Formation
Unit of	Lias Group
Sub-units	Shales With Beef Member, Black Ven Marl Member, Belemnite Marl Member, Green Ammonite Member
Underlies	Dyrham Formation, Marlstone Rock Formation, unconformity with Gault (Charmouth area)
Overlies	Blue Lias Formation, Scunthorpe Mudstone
Area	Wessex Basin, Worcester Basin, East Midland Shelf
Thickness	~335 m
Lithology
Primary	Shale, mudstone
Other	Limestone, sandstone
Location
Region	England
Country	United Kingdom
Type section
Named for	Charmouth
Location	Cliff and foreshore exposures between Seven Rock Point and Golden Cap, Dorset

The Charmouth Mudstone Formation is a geological formation in England, dating to the Early Jurassic (Sinemurian–Pliensbachian).^[1] It forms part of the lower Lias Group. It is most prominently exposed at its type locality in cliff section between Lyme Regis and Charmouth (alongside the underlying Blue Lias) but onshore it extends northwards to Market Weighton, Yorkshire, and in the subsurface of the East Midlands Shelf and Wessex Basin. The formation is notable for its fossils, including those of ammonites and marine reptiles and rare dinosaur remains. The formation played a prominent role in the history of early paleontology, with its Lyme Regis-Charmouth exposure being frequented by fossil collectors including Mary Anning.