North Pembrokeshire coast St. Justinians to St. Non's Nay

St. Justinian's - Ramsey Sound - Porthlsyg Bay - Porth Clais - St. Non's

Wednesday 18th September

Sketches at http://artywater.blogspot.co.uk/2013/09/sketches-from-north-pembrokeshire.html

Dry all day, with mix of cloud and sunshine. Cold in the windier bits. Paths busy in places, awkward where narrow and exposed near cliff edges.

Lifeboat station - St. Justinians

Ramsey Sound and Ramsey Island

Cambrian sandstone near St. Justinians

Took the 9:00am Celtic Coast bus (minibus) from Oriel y Parc  - all journeys £1 singles and got off at St. Justinian, near the Chapel ( in private garden) and lifeboat station. Outcrops of the grey-purple Cambrian sandstone. From here, we began walking south along the coast path, with Ramsey Sound and Ramsey Island on our right. There were several remote, sheltered coves, where we saw quite a few grey seals, in and out of the water, one of them being swept along by the pull of the tide, albeit at the shoreward edge. 

Grey seals

The tidal race through the Sound was impressive, the roughest bit being The Bitches – very choppy white water racing between rocks just offshore from the island, birds above the wake. On our side of the water, a gannet. As the Ramsey Sound is another area where water is funnelled through a narrow channel, I wasn't surprised to see strong currents / tidal racing here, the rocks at The Bitches, aggravating the turbulence. There was a definite strong movement of water all along the Sound, the tide ebbing. What was more, the rough water / the strong currents / white breakers / larger scale swells persisting some way out to sea, at least half the length of the island again. There was a full Moon on the Thursday (19^th), making for spring tides (more about that in a later entry about the Severn Bore). I would like to have spent more time here sketching, but it was cold in the wind.

Tidal Race in Ramsey Sound - "The Bitches"

Both the wind and the sea calmed down as we rounded the headland and began heading east along the coast, now facing the more sheltered St. Brides Bay. There were clear views all along the near coast towards Solva and all round St. Brides Bay to Skomer Island, silhouetted against the sun. The rock formations continued to impress, though we didn't see any more seals. Some horses, shortly after we rounded the headland. As we stopped for a snack and enjoyed the view, we were unaware of one quietly coming up the hill behind us.

Pebbles at Porthlysg Bay

Explored and had our packed lunches in Porthlysg Bay. Rock outcrops here guided by several faults in / near the bay trending southeast. In the cliffs another outcrop of the Cambrian purple grey and green sandstones, wedged between to faults. Pebbles on the shore of similar coloured conglomerate. Either side of this outcrop, the Neoproterozoic volcanics. Gold colour to these cliffs. Layers foliated, steeply dipping and contorted. There was granite, also Neoproterozoic, on the east side of the bay, though didn't get round to that on the shore, and it wasn't obvious when we walked over it back on the coastpath after our stop. While on the beach, I sketched looking out to sea, towards the islet just offshore, formed of the granite. Granite bounded on both sides by faults. Back on the Cambrian sequence, continued on to Porth Clais.

Porthlysg Bay

Just before we rounded the cliff above the harbour, view across to the steeply dipping thickly bedded sandstones, pictured in the geology books. The narrow harbour inlet here, is the outflow of the river Alun. The harbour was virtually empty at low tide, the boats high and dry, the river running as just a small trickle nearer the east side. A small stone harbour wall near the seaward end, only accessible on the east side. We followed the path up to the road and crossed the bridge over the stream at the head of the harbour, where we'd come through on the bus this morning. More lime kilns. The path then ran along the cliff on the east side. Strangely, looking back down to the harbour, we saw a guy drive a standard hatchback car down there. Though this wasn't a thickly mudded harbour, it still didn't look suitable for an afternoon drive. Hope he knew what the tie was doing and didn't stuck. As he stopped and appear to moor it to his boat, assumed he probably did, though the classic builders backside was in our full view as he bent over, stood at the forward end of his boat.

Porth Clais

Steeply dipping Cambrian sandstone beds at Porth Clais

Coasteerers near Porth Clais

Coasteerers near St. Non's

Above the next bay, we found somewhere down a bit, off the path overlooking more of the steeply dipping sandstones. I tried sketching them, initially interested in the rocks, but was diverted by a party of coaststeerers. These are people, in this case predominantly in this case big young burly blokes, in hard hats and wet suits who jump off cliffs and ledges into water. We watched them dive and splosh, some of the more expert ones somersaulting. They made their way through the natural arch to jump off somewhere a bit higher. We Saw them in action again on the other side of the promontory, then out of the water, heading from St. Non's Bay car park, following the same path as us into St.David's at the end of our walk.

Leaving the coast path at St.Non's, we passed the remains of a chapel, built on the site where St. Non is said to have given birth to St.David, in a storm, in the sixth century. A newer chapel further up the hill here. Where we left the coast path, a well and shrine.

 

Pembrokeshire Geology Notes

With reference to BGS Geological maps – Bedrock Geology 1:625000 south sheet, St. David’s Head 1:5000:

South Pembrokeshire  - mid Palaeozoic sedimentary - Silurian, Devonian, Carboniferous . Shaped by the Variscan Orogeny during the late Carboniferous. Rocks highly folded and steeply dipping. SE Pembrokeshire is similar to The Gower, Carboniferous Limestone series, still part of the south Wales syncline. Mid Pembrokeshire, inland of St. Bride's Bay, mainly Silurian, Ordivician. Carboniferous Coal Measures at Newgale, at the north end of the bay, on the south side of the fault. North Pembrokeshire - remnants of the Caledonian Orogeny, during the mid-Palaeozoic. Numerous faults, mainly striking E-W, including Solva where the harbour has been eroded along a fault zone in Cambrian and Ordovician rocks. North of St. Bride's Bay, early (lower) Palaeozoic -  Cambrian and Ordivician sedimentary shales, mudstones and sandstone. Ordivician volcanics (rhyolite lavas, tuffs) north of St. David's Head, Ordivician intrusives - dolerite, gabbro at St. David's Head, forming the hills. Also Ordivician, intermediate diorite intrusions, including The Gribin at Solva - outcrops of a sill?  Neoproterozoic granites and volcanics - lavas, tuffs, agglomerates. Exposed at Whitesand Bay. In the Cambrian, the Solva Group - mudstones, sandstone, greywackes. Cambrian sequence along the coast between Solva and Porth Clais to the south of St.David's. These include the purple-grey sandstone used to build St. David's Cathedral. Interestingly, as on the Gower, some springs inland, the river Solva's headwaters issuing from them. As these rocks are very old, therefore well cemented, they will be impermeable. Perhaps water percolates along joints.