Glaciation and glacial features of the Irish mountains

This presentation by Peter Wilson looks at how glaciers were powerful agents in shaping Ireland’s mountain landscapes, creating many of the dramatic landforms that can be seen on mountain walks.

After the Ice

In this talk, Peter Wilson deals with the natural landscape changes that have occurred in the mountains since the ice disappeared about 12,000 years ago, and some of the other features that give Ireland’s mountains their distinctive characteristics. 



From Rocks to Ridges

In 2015, with funding assistance from the Northern Ireland Challenge Fund, and in co-operation with the Ulster University and the Geological Survey of Northern Ireland, mountaineering Ireland published 'From Rocks to Ridges - a guide to the Formation of the Mountain Landscapes of the North of Ireland'.

The publication can be downloaded here

Soon additional information on the subject of Geology & Landscapes in the Republic of Ireland will be added to this page. If you have suggestions for inclusion, or feedback on 'From Rocks to Ridges' please email


These are areas that are designated for their special geological heritage and features, and aim to discover and celebrate the links between geological, natural and cultural heritage, through promoting sustainable tourism that benefits the local community. They have strong educational and research functions. 

Ireland currently has three UNESCO Global Geoparks: 

1. Burren & Cliffs of Moher, Co. Clare - 530km2 Geopark. Excellent Fact Sheets covering how features in the Burren were formed HERE. The Burren’s oldest limestone rocks now visible formed in shallow, warm, tropical seas 10 degrees South of the equator beginning about 330 million years ago. Fossils, the skeletal remains of marine organisms which drifted to the seabed and became embedded in calcium carbonate layers, can be seen. These layers took approximately 20 million years to form as limestone.
Upland karst regions in Ireland are important for heritage and tourism and support a unique ecology such as that of the Burren's terraced and fissured hillsides. Karst is limestone rock that has been dissolved/changed by rain water (which is slightly acidic) over time. Rain water seeps into cracks in the rock, and the carbonic acid dissolves the rock creating underground streams and even cave systems over 15km long such as Pollnagollum, Co. Clare. Much of the largest springs in Ireland also emerge from karst. See more info here
2. Copper Coast Geopark, Co. Waterford - The rocks of the Copper Coast comprise different geological events over 460 millions years which all began when magma rose from the depths of the earth to pierce the ocean floor, near the South pole. The land that would become the Copper Coast started to drift northwards, towards the Equator. While drifting, previously formed rocks were uplifted during mountain-forming processes and then exposed to the surface about 360 million years ago. The Copper Coast kept on drifting to reach its actual position. Andesite, a form of volcanic rock can be seen there amongst other rocks.
3. Marble Arch Caves (Cross-Border) Geopark, Co. Fermanagh and Cavan – The Park stretches 50 miles from Lower Lough Erne to just north of Cavan town, taking in Cuilcagh Mountain. The extensive cave system was formed some 330 million years ago during the Carboniferous geological period out of fossil-rich limestone from accumulation of mud at the bottom of the tropical sea then covering Ireland. See also: Cuilcagh Mountain Park, 2500 hectares on northern slopes of Cuilcagh. ‘It is quite mind-boggling to think that as you ascend to the summit of Cuilcagh Mountain, you are climbing up through geological time, covering a period of about 8 million years in just less than 700 metres.’ See also article by Centre for Cross Border Studies. 

Ireland also has Aspiring Geoparks:

Kerry Geopark - The South Kerry region of mountains were formed over the last 600 million years, 5km thick sandstone were folded and contorted to create this range. These were weathered down over the ensuing hundreds of millions of years, sculpted later by the Pleistocene Ice Age. Includes the Coral Beach at Gleesk Pier, Sneem (one of only two in Ireland, this ‘coral’ beach is made from tiny pieces of dried and sun-bleached algae rather than sand).

Joyce Country Geopark, Co. Galway and Mayo – in early stage GeoPark development. See the report and review of their progress and public and stakeholder consultation process here

Landscape & Geology - Mountain Ranges


Sperrin’s Gateway Partnership, Co. Tyrone and Londonderry - The uplands of the Sperrin Mountains and the Donegal Highlands were formed due to the collision of two huge supercontinents about 450 million years ago, coming together to form the island of Ireland. A large part of the project is the Upper Moyola Valley and Slieve Gallion, mainly within the designated Sperrin Area of Outstanding Natural Beauty. It is also recognised as an Environmentally Sensitive Area in terms of its key habitats including the River Moyola and the upland blanket bog and moorland important for breeding birds and other native wildlife.

Mourne Mountains, Co. Down – Mourne Heritage Trust: How Mourne Mountains were formed and Geological Fact SheetTwelve peaks >600 metres in height including Slieve Donard, Northern Ireland’s highest mountain at 850m. While granite (an igneous rock) mountains dominate the Mournes, much of the area (like most of Co. Down) is underlain by Silurian geological period rocks of shales, mudstones or greywackes (all sedimentary). These formed over 420 million years ago, from mud, sands and silts lying at the bottom of an ocean known as the Iapetus Sea. 

North-West plateaus of karst - Co. Sligo, Leitrim, Cavan and Fermanagh. See image and explanation on Geological Survey Ireland. The cliff at Ben Bulben, Co. Sligo, in the Dartry Mountains is known as 'Table Mountain'. Benbulben was formed as a result of the erosion of limestone and shale, and is designated as a County Geological Site. Co. Sligo also hosts the vast Diarmaid and Grainne's Cave, at Gleniff. 


Many of the highest summits in Dublin and Wicklow Mountains, a low-lying plain in Co. Carlow all the way through to the Blackstairs Mountains, are underlain by a 1,500kmarea of granite, the largest body of Caledonian granite in Ireland or Britain. In the Glendalough and Laragh area by the roadsides exposures of this 'Leinster granite' are visible. (The Caledonian orogeny was a mountain-building period recorded in Ireland, north Britain, Scandinavia, Svalbard, eastern Greenland and parts of north-central Europe, approx. 500–390 million years ago. It was caused by the closure of the 'proto-Atlantic' Iapetus Ocean when two mini-continents collided with a larger one, creating a new landmass.)


The southern valley karst, Co. Cork, Kerry, Tipperary and Waterford - Erosion on the folded limestone rock from a mountain-building geological time some 280 million years ago resulted in distinct sandstone ridges of the Galtees and Knockmealdowns separated by limestone valleys drained by large rivers such as Suir, Lee, and Munster Blackwater. 


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