SUBMERGED FORESTS
It’s so easy to think that everything stays the same. For a start, the coast doesn’t. It comes and goes over geological time according to the rise and fall of the sea level. The remains of forests, overwhelmed by sea level rises perhaps thousands of years ago, are revealed on some shores as sunken relics occasionally showing at low water or when storms have scoured the overlying sand away.
Round the Cornish coast there are fragments of sunken forests on the beaches at Mounts Bay near Penzance, and near Rock on the Camel Estuary.
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| Car keys show the scale. Numerous twigs embedded in the peat after storm exposed these remnants. We also found what looked like part of a deer leg bone. Someone took it to get it identified and possibly dated but we have never heard a verdict. |
Following Storm Imogen a few years ago we went to see the remains of trees which had been submerged then re-appeared on the beach at Millandraeth near Looe. The sky was so dramatic that I took pictures of the squalls and forgot the submerged trees.
These trees were inundated at various times in the post Ice-age by sea level rises or the silting or blocking of river-mouths. Trees were overwhelmed and then preserved in the waterlogged, oxygen-deprived sands and silts that covered them.
There are more submerged forests in places on the Welsh coast. After the retreat of the ice in the last ice age some 12,000 years ago, parts of the Welsh coast were a land of low-lying hills, with ever-shifting rivers flowing over marshy flood plains. It gradually became wooded with pine and birch and later, Oak and Hazel . Alternating rising sea levels and sinking land resulted in the periodic but overall, inundations.
A denuded sheet of peat, no more than 12 or 15 inches thick lying on a bed of blue clay is dated at about 5500 years before present (BP) that’s in the Bronze Age. Within and on this peat are the remains of trunks of Scots Pine, fragments of Birch and Hazel bark and numerous Hazel nuts. This ancient forest is believed to have been growing in a marshy hollow within the glacial material. These remains are usually protected by the beach sand, but storms wash the sand away, and even during the twenty years this place has been known by Kim, it is being eroded away.
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| Exposed trunks at Porth Neigwl. |
Two great storms, in 2015 and then in 2019 revealed once more the long-known sunken forest near Borth on the Cardigan Bay coast of Wales.This great spectacle was first documented in the 1100’s by the chronicler Gerald of Wales Geraldus Cambrensis.
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| Borth beach, the remains of the forest being revealed like sharks' fins as the tide went out. |
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| More trees showing as the tide went out further. |
From my notes at the time:
We went to Borth in Cardigan Bay to look at it in February 2015 a little before low water. It was the biggest and most dramatic spread. Looking across it resembled a vision of scores of sharks’ fins just breaking the surface of a hostile sea. As the tide went out further we saw two areas of peat and stumps ; the first and smaller area at the northern end of the beach we looked at first. The main lot was further south, opposite the beachfront hotels etc . This more southerly part was huge in extent, with areas of peat exposed, which was eroded in channels at right-angles to the sea as at Porth Neigwl. The trees were either growing in or had been engulfed by, the peat, which was fine-textured and black, and in places they had been bored into by piddocks or a similar kind of mollusc. Some stumps still had remnants of bark, apparently pine and birch. Oak has been seen there too I believe. Some of the stumps were big and with root plates spreading several yards across. Some you could still count the growth rings; upward of 120 years on one. In one place a big stump was growing above another smaller tree, an earlier forest apparently. The trees were pretty close together in places. This forest has been found to have the remains of oak, Pine, Birch and Willow , dated to the Bronze Age, between 4000 and 5000 BP. There are large numbers of very big stumps, their roots running all ways, as well as fallen trunks.
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| Exposed trunk. |
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| Stumps and roots. |
In one place there was a double row of sharpened, shaped oak stakes stuck in a straight row some 6+ yards long, the rows about 3 ft apart. A label on one said it was sharpened oak, sampled Oct 2014. I’d like to know what they reckoned it was.
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| Upright stakes of ancient causeway. Note the lengthways poles to make the walkway. |
I read later that these uprights were the remains of a causeway built in the Bronze Age, with coppiced poles laid between the uprights to form a walkway. I wonder where it was going? Apparently, across a salt marsh towards the sea! In one area nearby, the remains of ‘fossilized’ footprints were found in 2012 , of cattle and sheep or goats, and, movingly,those of a child of about 4 years’ old, with even the imprints of the toes showing.
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Very interesting Mary. Not sure if you are aware, but there is a similar submerged forest at Bude on their beaches occasionally revealed after storms.
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