The Hastings Beds in turn form part of the Wealden Group which underlies much of southeast England.

[3] The Lower Tunbridge Wells Sand shows the best cyclic fining up sequences in the formation.

[4] A massive thick cross bedded fine to medium grained quartz sandstone separates the Tunbridge Wells Sands from the overlying Grinstead Clay.

This boundary is often indicated on maps by spring lines and seepages, where groundwater percolating through the permeable Tunbridge Wells Sand is forced to surface at the junction with the Wadhurst Clay.

[4] Landslips often occur at or close to the lower boundary of the Tunbridge Wells Sands, between it and the underlying Wadhurst Clay Formation.

This results in the saturation and weakening of the upper portion of the Wadhurst Clay, increasing the chances of failure.