Aust Cliff under the Severn Bridge on the east bank of the Severn Estuary exposes a sequence of layers of rock that both appeal to the eye and to the fossil specialist. It’s a section through an area that was near the equator in the Triassic period, 230 million years ago. The area was alternately a lake (represented now by a layer of red mudstone) which dried out as salt flats (now white gypsum).
The upper layers (yellow/green and brown layers) are more recent, 210 million years old, representing a tropical sea; these layers are one of the UK’s most important sites for fossils of marine reptiles. Aust Cliff overall is a site unusually prolific in fossil finds, thus is classified as a site of special scientific interest (SSI).
When I was cycling to there as a schoolboy, the Aust Cliff site with its range and number of fossil finds, was important in determining the sequence of evolution of the fossil animals from the Triassic era. This work would now be regarded as calibration and/or confirmation of dating by radioactive isotope techniques.
My telephoto view across the Severn Estuary from Beachley avoids the perspective distortion common in photos from the cliff shoreline at Aust.