The South Pembrokeshire coast continues its spectacular scenic way as you travel eastwards from Manorbier to the middle cove known as Church Doors at Skrinkle Haven. The intervening mile or two sees a transition from the older red Devonian rock to younger grey Carboniferous limestone higher in the geological succession. Looking down on the bay you can see that it is divided into three parts by two seaward projecting ridges of rock known as Church Doors and Horseback.
The rocks around the bay are now stacked in remarkable vertical layers after earth movements have altered their position from the original horizontal strata. To the right of the steep metal staircase as you descend to the beach, Avon Group Limestones, formerly known as the Lower Limestone Shales, are made from thousands of very fine layers alternating with narrow hard bands that underlie the pebbles and boulders of the shore, and are exposed in the cliffs and a narrow promontory. These strata are collectively referred to as the Church Doors Limestone.
A small natural tunnel, accessible only at very low tides, passes through the promontory from the middle cove to the west cove of Skrinkle Haven. At the moment that tunnel seems to be the only way of getting to Skrinkle Haven proper but it use is not recommended. It is only open and available for a very short time and it is easy to get stuck on the other side with no way up the cliff as the tide rises. Also, the seabed level on the far side is a lot lower that the Church Door side and water rises comparatively much faster than in the middle cove making it additionally dangerous.
The staircase down to the beach marks the point at which the Avon Group limestones are replaced by Pembroke Group limestones. Behind and to the left of the steps as you reach the beach, there is a transitional zone marked by an increase in the proportion of limestone and chert beds. The limestone is faulted and has many white calcite veins. The promontory known as the Horseback is composed of Black Rock Limestone and has an incredible natural arch where blocks of stone have fallen. It is interesting to note the texture of the barnacle encrusted rock at the waterline with its marked pitting caused by bioerosion.
References
Allaby, M. 2008, Oxford Dictionary of Earth Sciences, Oxford University Press, 3rd Edition, 978-0-19-921194-4.
George, G. T. 2008, The Geology of South Wales: A Field Guide, gareth@geoserv.co.uk, 978-0-9559371-0-1, pp 22 and 137-141.
Howells, M. F. 2007, Wales, British Regional Geology, British Geological Survey, Nottingham, Natural Environment Research Council, 978-085272584-9, pp 112-120.
Jessica's Nature Blog 
Given our human reference point it’s always hard to imagine the amount of time it took for the layers of rock to be reoriented in such a way.
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Beautiful! 😊
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Thank you, Julie.
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Yes, it is difficult to get your head around the idea of such a tremendous passage of time and the slow inexorable processes that have contributed to such fantastic geological phenomena.
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What an interesting formation. I can see what you mean about the bioerosion. I’ve never seen that effect before.
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The natural sculpturing effect on the waterline is fairly common in the Carboniferous Limestone that I have seen on the South Wales coast but I don’t know how often it occurs in other rocks and locations.
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Wow, I would be so excited to see these rocks, and that arch! What fantastic layers and formations. I love the way the lichen is travelling along all the cracks. Looks a beautiful place, and one I’d never heard of.
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Remarkable looking place Jessica. The photos do a great job of capturing the beauty as well as the the geological interest. Looks like it would be a great film location.
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We were entranced by this beautiful South Pembrokeshire coastline and have vowed to visit it a lot more. The scenery and geology are incredible. There are islands to explore too, such as Caldy which is visible just offshore from the cliff top above Skrinkle Haven and Church Doors.
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Yes, I could imagine it as a setting for a film, maybe a children’s adventure story where they crawled through the tunnel to discover the west cove and its treasures. I had hoped to get through it myself but although the tide was low on the Church Doors side, the water was deep on the far side. I would have needed a swimsuit and was not brave enough or fit enough anyway to get through – and I was afraid of not getting back again. No one else did it either. Great shame the path from cliff to the far beach was no longer usable.
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Fascinating and lovely – VG photos to illustrate as well. And Skrinkle is a name to conjure with. RH
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Thank you, RH. I would have loved to have seen skrinkly rocks.
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