ROCK STARS OF THE WELSH COAST
IT’S an iconic part of the Welsh coastline – but there will come a time when the Green Bridge of Wales “will be a bridge no more”. The dramatic natural rock arch and rock pillars on the southwest coast of Pembrokeshire attract people from far and wide and is one of the most famous landmarks in Wales.
The sea arch – some 80 feet high and spanning 66 feet – seems as solid as, well, a rock. But thanks to the unforgiving action of the sea and waves, it’s forever changing and getting smaller by the day.
It’s difficult to see the change day by day, but when you compare two pictures, taken from the same place but a decade apart, it’s clear to see the Green Bridge is suffering.
A huge chunk of limestone rock fell off during Storm Ophelia in 2017, one of the biggest changes in recent years. And continued erosion is “inevitable” as extreme storms become more frequent with climate change.
Side by side, the difference is stark. Does that mean the future of the Green Bridge is hanging in the balance?
We asked James Parkin, the director of countryside, community and visitor services for the Pembrokeshire Coast National Park, if its days are numbered.
This is what he said: “Unfortunately, in 2017, Storm Ophelia meant that the Green Bridge of Wales suffered irreparable damage. It lost a lot of its limestone rock and a huge chunk fell into the sea. Eventually the arch will erode away completely, and it will be a bridge no more.
“As an authority, we undertake regular geological surveys as potential cliff falls are a major consideration with regards to the coast path but, due to climate change, further storm events, sea-level rise and associated coastal erosion are inevitable.”
It’s difficult to grasp the scale of the impressive rock arch without standing on the edge of the cliff yourself. When birds aren’t nesting, it’s even possible for people to walk along the top of the arch, although that’s not something for the fainthearted.
To think there’ll be a time when that’s not possible is sad indeed. Once the arch collapses, all that will be left are stacks.
There are already a number of stacks left in the area, which is designated as a Site of Special Scientific Interest (SSSI), a Special Protected
Area (SPA) and a Special Area of Conservation (SAC) in recognition of its rich geological and fossil heritage.
Stack Rocks, less than 100m away from the Green Bridge, are the remnants of a similar process from hundreds, if not thousands, of years ago. Also called Elegug Stacks, their name comes from the Welsh term for the guillemots and razorbills that nest there. The rocks are primarily carboniferous limestone. Over time the combination of wind and rain has eroded the stone. The waves crashing against the cliff have driven pebbles into the rock, and the limestone has also been dissolved over time to form deep caves on both sides of a headland.
Over millennia the caves met, creating a passage through the solid rock – the Green Bridge. It’s the same process that created Durdle Door in Dorset.
Over time the central arch will erode and collapse, leaving the Green Bridge a bridge no more, as Mr Parkin pointed out.
It will become a sea stack like the neighbouring Stack Rocks.
The obvious question is why the entire rocky headland didn’t erode away. The answer is that the far end of the Green Bridge stands on a much harder rock foundation that resists the force of sea and wind more strongly than the limestone.
It should come as no surprise that the area around the Green Bridge is very popular with climbers, though climbing activity is limited to certain times of the year so it does not interfere with the large population of nesting seabirds.