Allhallows-on-Sea offers intermittent London Clay collecting on the southern Thames shore beside the holiday-park seawall. Its chief interest is crustaceans preserved in nodules, particularly crabs, although clay and shingle can remain hidden beneath silt. A visit is most rewarding when firm upper-shore material is exposed and the tide allows a comfortable return along the seawall. Eocene, Foreshore, Rating: ♦♦♦