Caldon Low: SK 077492
This outstanding site shows a Carboniferous Limestone section of considerable palaeogeographic and stratigraphic significance. During the Lower Carboniferous the site lay in an area at the margin of a shelf area, extending north from the Wales-Brabant landmass, and of the so called Widmerpool Gulf. The sequence exposed includes the Hopedale Limestone (Asbian) and the underlying Milldale Limestone (precise age uncertain) with, separating the two formations, the quartzose Caldon Low Conglomerate. It has been suggested that the unconformity beneath the conglomerate includes the entire Holkerian Stage. The Caldon Low Borehole put down here proved a sequence of probable Devonian to Lower Carboniferous (Chadian) rocks not exposed at any outcrop in the Staffordshire-Derbyshire area. Research on spores from the section afforded by the borehole proves that the initial Carboniferous marine transgression in the Staffordshire area occurred in the early Tournaisian.
Source: SSSI citation, English Nature