Ashgill Series

Also called  Ashgillian Series,  the uppermost (in ascending order) of six divisions constituting the Ordovician System, representing all those rocks deposited worldwide during the Ashgillian Age (448 to 438 million years ago). The name of the series is derived from the Ash Gill Slates in the vicinity of Coniston in the Lake District of Cumbria, Eng., which is the type area for rocks of this age. Cautley, also