Rye Castle Museum

How the Marsh was Formed

By Jill Eddison

is one of the three great marshlands of England. Nearly all this 100 square miles of flat land lies below the level of high tides. It is flanked on south and east by the sea.
 

 Origins

The Marsh has been formed in the 10,000 years since the last Ice Age. After the ice melted, sea leve1 rose quickly up to 6,000 years ago. The whole area of Romney Marsh was a wide sandy bay and, as sea level rose, the sea piled in layer upon layer of sand until it was about 10 metres deep.

Then a great change took place, which altered the area for ever. A massive supply of flint pebbles (known as shingle or, commercially, as gravel) which had been eroded out of the Chalk of Dorset, Hampshire and Sussex during the Ice Age, began to arrive from the south-west, and built out a great bank towards Hythe. Behind this barrier, the sandy bay became salt marsh, with fresh-water swamp in the valleys.  

Since then the outer coastline, consisting of massive barriers of shingle, has been continually changing, and so have the tidal inlets which once provided harbours near Hythe, Romney and Rye.

How this Happened

You can see the sea and the wind at work today, building up and altering the coastline, just as happened in the past:

1. Shingle is moved along by the waves. Go down to any shingle beach and watch what happens when a wave breaks on the shingle. Pebbles will be thrown up the beach, probably at an angle. In a storm, when the waves are high, and you will see great quantities of the beach being moved along.
 

2. Salt marshes are built up by the inter-action of plant-growth and deposition of sediments. The English Channel looks dirty. This is because it carries great quantities of fine- grained sediment suspended in the water. The tide flows in round the end of the shingle banks, or up river estuaries, into calm water behind. At high tide the movement of the water ceases, and the load of sediment is deposited. When this has built up sufficiently, plants specially adapted to grow in salt water flourish. Their leaves trap more sediment, and thus help to built the surface up above the level of all but the highest tides. At this stage, the twice-daily flow of the tides is limited to channels winding around clumps of plants.

3. Sand Dunes The oldest dunes at Camber are only 200 years old, and parts are still growing out to sea. As the tide goes down the wide sandy beach dries out. If the wind is blowing onshore, it picks up some of that sand, and blows it inland to form the dunes. As a result the coastline near the coastguard cottages east of Rye Golf Club has grown outwards by 100 m. in the last 20 years. This can be seen happening especially in winter gales.

Nature built up and altered the Marsh in these ways.

The Roman Marsh

Scattered archaeologica1 evidence indicates that the Marsh was still a salt-marsh in Roman times. Burnt clay (briquetage) and broken pots provides evidence of a widespread salt-extraction. Professor Barry Cunliffe has suggested that men would have lived on the Marsh in summer, using the excellent pasture for sheep and cattle, and evaporating salt (a very valuable commodity) from sea water at the marsh edge.
In winter these people probably retreated to the surrounding upland. There is no known evidence that the Romans built defences to keep out the incoming tides.

In about A.D. 350, a marsh inlet was guarded by massive shore fort on the hillside below Lympne. This was a base for the Roman fleet, the Classis Britannica, which was attempting to ward off Saxon invaders.

Thus, except for the shingle barriers, most of the marsh was under water until at least Saxon times. It was a changing kaleidoscope of land and water, changing from high to low tide, from season to season and from century to century.