There are several Marine Bands in the area, layers of shale that represent areas where a shallow sea invaded something like a large river delta swamp area and for a time marine animals lived and died there, later to become the fossils we find today.
The Marine Bands are associated with the coal seams, as the coal formed in the swamp conditions that the incoming sea was to replace, forming the marine band.
We find the marine fossils usually where a Marine Band outcrops on the surface, but mining or quarrying can also reveal fossils.
Marine Band Goniatite Fossils image by munki-boy
There is an interesting Marine Band outcrop in the stream below the ruins of Higher House
