A submerged landscape exists where an ancient land surface can be found preserved underwater. This includes submerged forests and ancient peat beds. These land surfaces often contain invaluable evidence of past climatic conditions.
There are seven areas along the coast of Dorset where evidence has been found of former land surfaces, which now lie below high water mark. In all cases, study of these sites, has provided unique evidence of ancient landscapes and the people who lived there.
Around Christchurch Harbour archaeological work has, quite naturally, been concentrated on Hengistbury Head where a major prehistoric port has been discovered. However excavation in the 1960's revealed a Mesolithic occupation site in Mother Siller's Channel, which cuts through Stanpit Marsh, on the north-western side of the Harbour, which dated from about 5000 BC. The people who had camped at Mother Siller's Channel had clearly visited the Isle of Purbeck as they had brought heavy blocks of stone from there to surround the hearth.
Christchurch Harbour has recently been recognised as a wetland site of national importance for its archaeology.
A 'submerged forest' exists near Bournemouth Pier. It was first recorded by Sir John Evans, in The Ancient Stone Implements Weapons and Ornaments of Great Britain 1872.
I must, however mention the existence of a submerged forest, occasionally visible at low water, at the foot of the cliffs at Bournemouth &&. Mr. Albert Way, F.S.A., who has had the opportunity of examining some of the stumps of the trees exposed at rare intervals at low water, informs me that they appear to be those of the true Scotch fir. On occasion of one of my visits to Bournemouth, some of these stumps were fortunately visible, and were pointed out to me by Mr. Way at a spot but a few yards west of the pier, and between high and low-water mark. They appear to be of no very great antiquity, geologically speaking && as the trees, some of which were fully a hundred years old, grew on the surface of a thick bed of hard peat.
Peat deposits have been recorded within the harbour, but more important are the archaeological sites reported from the Intertidal zone and underwater. Off Brownsea Island a Roman settlement site was discovered below high water mark, whilst between Green Island and the mainland is to be found the remarkable Green Island 'causeway'. This pair of structures are now considered to be piers or moles, built in the middle Iron Age (about 200BC) to form a massive harbour. This structure is unparalleled anywhere in north western Europe. The site is being investigated by the Poole Maritime Trust and Bournemouth University.
Poole Harbour has recently been recognised as a wetland site of national importance for its archaeology.
Within the Fleet, coreing of the sediment has revealed ancient peat layers, whilst in 'Pirates Cove' an Iron Age salt boiling hearth has been discovered in the intertidal zone. For these reasons the Fleet has recently been recognised as a wetland site of national importance for its archaeology.
Off Chesil Beach, under Lyme Bay lie ancient peat beds. The story of the most remarkable recent discovery is told on the web page The Abbotsbury Beaver.
Tree stumps have been recorded from under the sea off West Bay. The first reference was by John Hutchins in 1774 who wrote.
Some years since, an extraordinary reflux of the sea at Bridport mouth, when nine or ten stumps and roots of large trees two, or three feet in diameter and three feet high, appeared, but were never seen since.
More recently divers have sometimes seen these tree trunks, to the west of the harbour mouth, when the sediment has uncovered them.
A 'submerged forest' was first reported off Charmouth in 1826. This has been dated to the twelfth century, by a wooden bowl found in the peat which was radiocarbon dated. Deer antlers have also been found in the peat. It is probable that the remains are those of a bank of vegetation that built up at the mouth of the River Char in the twelfth century, and was subsequently buried and preserved by a moving bank of sand and shingle, rather than an ancient land surface.
The Abbotsbury beaver
In 2000 the remains of a prehistoric Beaver were discovered at Abbotsbury, in a block of peat that had been washed up on the shore.