The locality lies within the Sabden Shales at the northwestern end of the Pendle Monocline and spans the Eumorphoceras - Homoceras ammonoid Genus-Zone. It is also the stratotype section for the the boundary between the Arnsbergian and Chokieran Stages. The Mid-Carboniferous boundary has been defined at the first entry of the conodont Declinognathodus inequalis about 9.4 metres above the Arnsbergian/Chokerian boundary and significantly is marked by a major mass extinction of faunas. Perhaps mass extinction was triggered by the collision of Gondwana and Laurasia.
Fossiliferous Sabden Shales |
