The Clavell Tower on the eroding Hen Cliff.

Soft shale cliffs are eroding fast. Soon the sea will break into the lower land behind the existing cliff line and the bay will widen dramatically.

The tower on the clifftop is now in danger of falling into the sea. For more evidence of rapid erosion look out for the WWII pillbox that was set snugly in the opening in the cliff where the stream emerges but now is exposed and crumbling on the beach.

The beach here is comprised of chunks of limestone toppled from the cliff along with the shale. The fragile shale breaks into thin sheets which rapidly wear into discs known as shale 'pennies' and then are ground away by the waves. Some of these rocks are oil bearing. Quite often a sharp petroleum smell arises from the debris of a cliff fall and it is possible to find limestone fragments with a strong natural odour.

Kimmeridge oil is extracted by the 'Nodding Donkey' on the clifftop. Despite being at the culmination of a visible anticline the source of the oil is a mystery for the drill string terminates in the cornbrash which cannot be the source. During the seepage from its secret reservoir to the well the oil is naturally filtered and emerges partially refined. Kimmeridge oil is pale green, translucent and as one oil-man put it, "Ready to drink."

Jurassic Coast | Itineraries Page