At its highest point, Ashplats Wood is about 130m (426ft) above sea level. The northern part of the wood is underlain by Tunbridge Wells sands and the lower slopes and adjoining fields are on Wadhurst clay.
The junction between the permeable sand and the impermeable clay is marked by the presence of seepage lines and springs. These areas are often indicated by the large grass-like plant, Pendulous Sedge.
Unfortunately the seepage and the clay can make it quite muddy in the winter months, but these Ghyll springs and streams are a feature of the Sussex High Weald and support rare and unique flora and fauna.
One of the seepage lines (right) where the sandy layer on top meets the impermeable clay layer below.
Fragments of so-called “Sussex Marble” (also known as “Winklestone”) have been found in the stream in Ashplats Wood, and a sample from there is shown in the local East Grinstead Museum (left) with a note indicating it was laid down about 140,000,000 years ago. The matrix is made up from freshwater gastropods, Viviparus winkles, with the pale calcified remains of the shells in a matrix of darker material.