Sedimentary rock boulders on the seashore extending into the sea

Another gallery depicting the amazing rock boulders on the seashore at Eype in Dorset, England, and the contexts in which they are found on the beach.

The cliffs at Eype, and the boulders on the beach below them, are made of Middle Lias sedimentary rocks from the Jurassic Period. It is difficult to judge the scale of the cliffs from looking at the photographs, so you might like to know that the silty sand and hard sandstone bands of the Three Tiers layers at the base can reach a maximum of 9m thick (although much of that is buried in this location); the clays and sandstones of the Eype Clay Member above that are 60 metres deep; on top of that the soft sands of the Downcliff Sands Member are 30 metres deep; and above that the soft sandstones of the Thorncombe Sands Member are 21 metres thick. This makes for a sequence of rock strata measuring a potential 120 metres (390 feet) in height – the measurements are approximate as the depth of the layers varies a lot.

In their book Classic Landforms of the West Dorset Coast, Brunsden and Goudie state that

The coastal cliffs of West Dorset owe their shape to the relief and orientation of the coastline, the variable properties or lithology of the rocks, the geological structure, the history of relative land and sea movements, the sequences of environmental change, the difference in erosional energy of the sea between the more exposed and sheltered parts of Lyme Bay, and to the complex sub-aerial processes which currently act on the cliffs themselves.

At Eype, the boulders on the beach demonstrate not only the variable lithology of the rocks in the cliffs above but also their structure. The alternating bands of different rock composition and colour are evidence for the cyclical nature of changing environmental conditions throughout geological history, including changes in sea level relative to land; while their presence on the seashore illustrates the ongoing erosional processes affecting the coastline to this day.

COPYRIGHT JESSICA WINDER 2014

All Rights Reserved

4 Replies to “Beach Boulders at Eype 2”

  1. Thank you. It is a fascinating place. So far I have only looked at the west end of Eype beach but next time I’ll examine the east end which has completely different geology because there is a fault line half way along the shore.

  2. I like to take the wider shots to remind myself of exactly where I saw the different features I captured in close-up images. It is useful when I get back home, to pinpoint the exact location – and in the case of geological subjects, this could be crucial in identifying the rock types and naming them.

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