St. Cyrus Beach: A story of fire and water

A landscape carved out by both volcanic lava flows and tumultuous rivers is clearly visible today at St. Cyrus beach

1. St Cyrus Beach cliff top walk, looking north. Image: Gavin Eardley

400 million years ago, in the early Devonian period, the landscape around St. Cyrus would have looked completely different to how it does today. The fertile arable land as we know it would have instead been covered in an arid landscape of black igneous rock (made from lava) with occasional oases containing some of the first plants and animals to colonise the land. If you could be transported back 400 million years you would see hot molten rock boiling up from deep within the Earth as lava spreads across the land through a network of lava tunnels, covering the landscape with successive blankets of lava. Then imagine a different kind of boiling and bubbling as those same lava flows are worn away by energetic rivers and streams, carving out channels and dumping their sediment load in the lakes forming on top of the lava plateau. All this is preserved in the sheer cliffs at St. Cyrus beach where the hard, stacked lava floes resist the pounding of the North Sea.

There are several places along the base of the cliffs where you can see unusual features like sediment-filled channels cut into the volcanic rock. Ripples and laminations (successive layers of rock that can usually be told apart by their colour) can often be seen in the channels, which contrasts strongly with the volcanic rock below. Traces of some of the first land-dwelling arthropods, or invertebrates, can also be found here in the form of little burrows seen in the sedimentary rock. These small creatures probably lived in burrows to help them survive in this inhospitable landscape.

Nowadays these picturesque cliffs and the sandy shore below are a National Nature Reserve because they provide an excellent habitat for wildlife, among them the most northern occurrence of various plant and insect species. The area is also a favoured spot for local paragliders looking to catch the onshore wind that is deflected skywards by the cliffs. Whether it’s for the beautiful sea views, unique geology or rich wildlife there are many reasons why a visit to St. Cyrus beach is a must.

Text contributed by Gavin Eardley

Find out more

St Cyrus National Nature Reserve: website with visitor information.

Field trip guide produced by the Aberdeen Geological Society: http://www.aberdeengeolsoc.org.uk/resources/Aberdeen-Guide/21-Devonian-of-St-Cyrus-and-Milton-Ness.pdf

Hole, M. et. al. (2013) Lava-sediment interactions in an Old Red Sandstone basin, NE Scotland In Journal of the Geological Society, Geological Society of London, vol. 170:641-655 http://jgs.lyellcollection.org/content/170/4/641

2. St Cyrus raised beach, looking south. Image: Gavin Eardley.

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