Birling Gap

I wrote this back in April, but did not get round to posting it. Birling Gap is on the Sussex Coast and is a low point in the cliffs seperating the Seven Sisters to the west from Beachy Head to the east.

On our previous visits to Birling Gap we have walked and sat on a substantial shingle bank at the foot of the cliffs.  This had a steep profile and a level top extending back to the base of the cliffs.  This must have protected  the base of the cliffs from wave action and considerably reduced the rate of erosion.  We were dismayed on this visit to see that much of the shingle had been washed away and only a thin shallow strip remained at the base of the cliff (see Photos).  The loss of shingle exposed chalk and sand on the beach and large pieces of rubble which, presumably have come from the collapsed buildings on the clifftop, including the Coastguard Houses.  

Birling Gap 2007

Birling Gap 2013

Comparing photographs taken in September 2007 and April 2013, there does not appear to have been a substantial amount of erosion.  It will be interesting to see what happens over the winter of 2013/14 without the shingle to protect the foot of the cliff.

Ten years ago there was a lengthy battle to save the cottages at Birling Gap by installing a breakwater at the foot of the cliffs.  Stories about the campaign can be found here Coast    Eventually this was rejected and the plans were abandoned.  Erosion proceeds at the rate of about two feet a year.

At Birling Gap the cliffs either side of the beach staircase are of Coombe Rock which derived from the chalk probably during the Devensian period when large amounts of this type of material was flushed from the dry valleys in the chalk.  Below the coombe rock is chalk which has been shattered and heaved by periglacial conditions (freezing and thawing), making the whole cliff area prone to marine erosion.  Erosion is faster here than on other parts of the cliffs, so a small cove may open up.

Castledon, R. (1996) Classic Landforms of the Sussex Coast. London: The Geographical Association.

This author mentions the shingle at  the bottom of the cliff. It may be that the erosion is part of the interruption of the process of longshore drift by coastal defences to the west of this point resulting in shingle being moved eastwards from Birling Gap, but not being replenished by fresh material from the west.

For more photos of Birling Gap see: http://www.flickr.com/photos/112963374@N07/11713471243/