Читать книгу The Ceredigion and Snowdonia Coast Paths. The Wales Coast Path from Porthmadog to St Dogmaels онлайн

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Cardigan to St Dogmaels

A short link on the south side of the estuary, via field paths and roads, leads to St Dogmaels and the official start of the Pembrokeshire Coast Path.

The Story in the rocks

One of the delights of the coast path is its ever-changing scenery, resulting from the varied underlying geology.

Between Porthmadog and a little north of Broad Water you encounter the oldest rocks along the path. These are called greywackes: hard, dark sandstones, alternating with softer slate and mudstones, formed 544 to 510 million years ago during the Cambrian period. Folded into a dome (the Harlech Dome), much eroded since its first formation, they rise from the coast towards the Rhinogs.

Subsequently the landmass that included Wales drifted north some 3000km (1865 miles) from the southern regions of the planet. Mudstones, siltstones and sandstones formed during this time occur along the coast between the Teifi and Ynys Lochtyn near Llangrannog.

Between Ynys Lochtyn and Borth the rocks of the later Silurian period comprise great thicknesses of greywackes, formed in fast-moving currents. The larger sand grains would settle out first, with finer muds on top, a sequence repeated many times and seen in layer upon layer of alternating strata in the cliffs. Most striking of all, between Cwmtydu and Borth, are the so-called Aberystwyth Grits, nowadays considerably contorted as a result of mountain-building forces.