Liscannor flags with Olivellite trace fossils and lichens in a wall at the Cliffs of Moher

A protective wall has been constructed to prevent accidents and damage at the edge of the Cliffs of Moher. The wall comprises huge over-lapping vertical slabs of Liscannor flagstones, locally quarried from the same Namurian siltstone strata that appear at the top of the cliffs. Originally this wall was built during the Irish famine in the 1830s to provide work for people who were on the verge of starvation. Some people think the wall is too high and impedes the views – but I think it not only serves to protect people who might recklessly climb on the cliff edge, and to protect the plants and birds that live on the edge, but it is also a subtle evocation of the silhouette of the cliffs beyond.

Some of the flagstones are naturally decorated with patchwork patterns of encrusting lichens. I’m not too sure why some slabs have lichens and others do not. Maybe, the clean slabs are relatively recent replacements.

Liscannor flagstones are also used for paving, and form the horizontal treads of steps that lead visitors to paths along the first few hundred yards of cliffs to the north and south of the visitor centre. The flagstones, in both the barrier walls and the paths, feature strange curvilinear patterns and textures which are trace fossils (also called ichnofossils), known as Olivellites. They are thought to be the fossilised feeding trails of marine gastropod-like creatures – made in much the same way that Acteon tornatalis ploughs a furrow in soft sediments of British shores today as it hunts down its prey.

The kerb-like stones that form the risers of steps on the footpaths are made of a different rock – an earlier Carboniferous limestone from the Burren. The stone is absolutely packed with fossilised corals (colonial, tabulate, and solitary forms), large brachiopod shells, and a few smaller gastropod molluscs. The Cliffs of Moher are a great wonder but the fossils, for those who notice them, are a small marvel of their own.


Cliffs of Moher Visitor Experience, Co. Clare – Visitor guide leaflet.

Sleeman, A. G., Scanlon, R. P., Pracht, M. & Caloca, S. (2008) Landscape and Rocks of the Burren: A special Sheet in the Bedrock Geology 1:50,000 Map Series, published by Geological Survey Ireland, ISBN 189970257-1.

Hennessey, R., McNamara, M., and Hoctor, Z. (Compilers) (2010) Stone, Water and Ice – A geology trip through the Burren, The Burren Connect Project, ISBN 0-9567204-2-9.


All Rights Reserved

11 Replies to “Flagstones & Fossils at Moher”

  1. nice job of looking and then telling, both with your lens and with your pens – uh, please uh, furgive…

    the lichen-no-lichen look can only be reflective of the radical rebuild of visitor amenities at the Cliffs several years back. those big vertical sides got moved around, and the rebuilders flipped half of them to catch your eye, trusting you would telegraph the phenom to a wider but less alert crowd. I dunno about complaints of too much safety deters access way back before the rebuild, but that rebuild added much between the visitor and the resource. thus the grumblings have amplified. I visited first in ’98 and it was relatively more wild and simple. and fun.


  2. Thank you for the comments and information, John. I guess organisations have become more health and safety conscious, aware of the probabilities and possibilities of accidents, and afraid of litigation. Nevertheless, the Cliffs are spectacular and the barrier rock slabs added to my enjoyment of the visit rather than detract from the views.


  3. all you say is valid, yet there remains a very important question about how public entities can best “improve” management of the visitor experience at sites of great natural attractiveness and significance. with loads of new money for a while, the irish nat’l gov’t seems to have served up too much bureaucratic intervention at the cliffs. seems to me that the thinking consumer of natural site experiences has something of a responsibility to cry “foul” when their public managers get it wrong by providing just a few tons worth of too much help.

    p.s…. sorry for the lengthiness, but the barrier rock slabs were always there, just in a less imposing way… always meaning back to perhaps the 1830’s, as i think i just read yesterday in exploring the subject of “liscannor stone”.


  4. true, obviously. I had some academic training in that field as a youngster, and worked many years in the resource conservation field for public agencies. Now I am many years removed and, so, see it from some distance and non-beholden perspective.


  5. I remember going to Moher in about 1989 and lying flat on the slab of rock to look over the very edge (taking great care). A brash tourist walked up to the edge right next to me – and the updraft took her hat up into the air. She lunged for the hat. Everyone thre felt their heart miss a beat as she so nearly went over the edge.
    I am so pleased that they try and keep people further back – for safety, let alone to avoid the erosion and damage to such a delicate environment (which i was unwittingly not helping on my visit)

    Liked by 1 person

  6. Yes, Coleshed, I am glad they put the barriers up, and such appropriate ones too, but many have complained it spoils the view. Your story brings out the goose bumps, it could so easily have been fatal – and nowadays with so many people taking “selfies” a barrier seems even more important.


Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.

%d bloggers like this: