The eastern half of the county is Upper Triassic Mercia Mudstone laid down with large salt deposits which were mined for hundreds of years around Winsford. Separating this area from Lower Triassic Sherwood Sandstone to the west is a prominent sandstone ridge known as the Mid Cheshire Ridge. A footpath, the Sandstone Trail, follows this ridge from Frodsham to Whitchurch passing Delamere Forest, Beeston Castle and earlier Iron Age forts.