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.

The beds adjacent to the junction of the Lower Jurassic Blue Lias and Charmouth Mudstone formations are intermittently exposed in cliff and foreshore sections over a distance of 8 km on the east Devon and west Dorset coast on either side of Lyme Regis.

In the East Midlands Shelf (northwards), where the Blue Lias is absent but the Scunthorpe Mudstone occurs, the base of the Charmouth Mudstone is taken at the base of thin pebbly ferruginous oolite (Glebe Farm Bed) or, in north Lincolnshire, at …

Above the Blue Lias Formation, the Charmouth Mudstone Formation (ChM), previously known as the Lower Lias Clay, consists of pale, medium and dark grey mudstone, calcareous mudstone and organic-rich mudstone.

The Charmouth Mudstone and Beacon Limestone formations form the youngest part of the Lias Group in the Mendip region, but substantial parts of this succession are missing, and the fossiliferous mudstones that form much of the remaining part …

The beds adjacent to the junction of the Lower Jurassic Blue Lias and Charmouth Mudstone formations are intermittently exposed in cliff and foreshore sections over a distance of 8 km on the east Devon and west Dorset coast on either side of Lyme Regis.

Charmouth Mudstone Lithology Dark grey laminated shales, and dark, pale and bluish grey mudstones; locally concretionary and tabular limestone beds; abundant argillaceous limestone, phosphatic or ironstone (sideritic mudstone) nodules in some areas; organic-rich paper shales at some levels; finely sandy beds in lower part in some areas.

Jan 1, 2005 · Temporary exposures in the Blue Lias Formation and the Charmouth Mudstone Formation, Lower Jurassic, between Hawkesbury and Gloucester, Gloucestershire, yielded many ammonites of biostratigraphical significance.

The Charmouth Mudstone Formation is a geological formation in England. It preserves fossils dating back to the early part of the Jurassic period (Sinemurian–Pliensbachian). It forms part of the lower Lias Group.

Thin (<10 mm thick) beds of laminated grey mudstone in the Dunscombe Mudstone and Blue Anchor Formations give rise to rotational and translational shear failures on the Devon coast.