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A special thanks to Sussex Wildlife TrustFriends of Rye Harbour Nature Reserve and Flag Ecology for their contribution to the funding of the new RX-wildlife website.

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9:21PM

Opposite ends of the spectrum

I have written before about the natural shingle wetlands on Dungeness, a series of water bodies created by the sea on the east coast of Dungeness.  As shingle is washed around the coast it sometimes forms natural hollows which, in time, find themselves separated from the sea by a broadening shingle beach and the early saline lagoons eventually become peat-filled fresh-water habitats like the Open Pits, until finally, on the eroding south-coast saline conditions return.  

These are the dying days of Abnor Pit and its fringing saltmarsh of sea purslane Halimione portaculoides, near Galloways.  It is progressively being buried by in-rolled shingle, with some of the material washed eastwards towards Dungeness Point, and this was all that remained at the weekend.

Another storm could bury the last square metre or two this winter, or it might persist for a few more years, the end of a structure that was probably formed in Roman / Anglo-Saxon times, and was significant enough to be given a local name.

As with a tumbled-down ruin it is sad to see the loss of such features.  It forces you to consider the life that once lived there.  Thirty years ago you could walk around the whole intact pit.  It is tempting to propose better coast protection on the south-coast of Dungeness to preserve these ancient features, but that would be a mistake.  A range of coastal species depend on such dynamic processes, and near the lifeboat station, a new pit has been formed courtesy of shingle washed from the retreating south coast.  Welcome changes in coast management have allowed shingle to start accreting on the east coast again and the beach has extended seawards significantly in the last few years.

And within this new stretch of shingle beach a new pit has been formed, the first for centuries. 

Our knowledge of the development of these wetlands has been informed by studying cores of the silt and peat accumulated in their beds, but the exact timeline is uncertain,  limited by our inability to date key events precisely using radiocarbon or other methods of dating peat, silt and sandy cores.  Here we have a rare opportunity to study and document the key processes of early pit development.

The early days of such a pit sees daily dry periods, as water drains through the porous shingle on the tidal cycle.  However silt is starting to accumulate and eventually it will form a seal, perhaps allowing the creation of a more permanent saline lagoon. 

  And plant-life has found its way there with rapid colonisation of three saltmarsh plant species, glasswort Salicornia spp, annual sea blite Suaeda maritima and sea purslane.

 Kent's youngest saltmarsh!

So, the destruction of an ancient pit provides material for its replacement.  Its survival depends on the vaguaries of winter storms and our desire to allow natural coastal processes.  If the storms of the next few years fail to infill this basin, and sediment supply is maintained I look forward to witnessing a process that has not been seen at Dungeness for a very long time.

 

 

 

                      

Reader Comments (1)

Thank you, Brian, for a truly fascinating and original article.

August 14, 2015 | Unregistered CommenterPatrick Bonham

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