(, Lower Tunbridge Wells Sand. Wadhurst Clay. Ashdown Sand, with Fail-light Clays at its base.
The sands are often false-bedded, the clays occur at varying horizons, and clay-ironstone andlimonite in the Wadhurst Clay was the chief source of the iron of the Sussex iron-works which flourished in the 16th and 17th centuries. A calcareous sandstone, known (from Tilgate Forest near Cuckfield) as Tilgate Stone, occurs at several horizons and is rich in reptilian remains, including crocodiles, Iguanodon, Hylcsosaurus, and other dinosaurs. These animals were discovered by Dr. Mantell in the Cuckfield district. Some hard beds in the Tunbridge Wells Sand form the remarkable Toad rock and the High Rocks near Tunbridge Wells. Beds containing small species of Cyrenia, a freshwater bivalve, are not infrequent, and fossil-ferns, borse-tails, cycads and conifers also occur.