The underlying rock is red Permo-triassic sandstone about 200 Million years old, which is known geologically as “St. Bees New Red Sandstone”. The St. Bees valley, which is much too big for the small “beck” that drains it, was formed by glacial action. The sandstone is never far from the surface and the smooth contours of the fields accurately reflect the underlying rock.
On the seaward side, the rock has been eroded by wave action to produce the spectacular 80 metre high vertical cliffs stretching from the Seacote foreshore to Saltom Bay, 4 miles to the North. The dramatic sandstone cliffs of St. Bees Head are a heritage coast, and have one of the largest seabird colonies in England. At Saltom there is an old alabaster mine and the geology changes to carboniferous sandstones.
At the west end of the St. Bees valley are the terminal moraines of the last glacier (12 – 14,000 years ago) which make an interesting golf Course. These unprotected cliffs are retreating at about 4 – 6 inches a year, and consequently this is one of the best places in England to look at a freshly-eroded cross-section of a glacial moraine. Several huge “erratics” are visible in the shingle.