The base of Cuilcagh Mountain is formed from limestone, as you walk up the mountain track towards the summit, the rocks change to mudstones and siltstones, with sandstone on top.
These rocks formed over 300 million years ago when the land that is now Ireland was covered by a shallow tropical sea near the Equator.
The remains of billions of tiny sea creatures drifted down as fine sediment and collected on the sea bed to form limestone. As sea levels fell the tropical sea was replaced with tidal flats, and then by a humid river delta eventually forming other sedimentary rocks – mudstones, siltstones, and sandstones.
Over time, the land pushed up out of the sea and moved north away from the Equator. Later still, the Irish landscape was altered by the erosive forces of nature including successive Ice Ages when massive ice sheets gouged the rocks beneath them. While these rocks are common in Ireland, it is very unusual to find such a complete sequence all in one place. 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 meters.
Cuilcagh many different natural habitats mean it is a perfect place to enjoy nature.
From the summit, there are breathtaking views of the surrounding countryside, including a sweeping expanse of blanket bog, stretching like a huge cloak across the middle slopes of the mountain.
This is one of the largest blanket bogs in Northern Ireland and one of the most intact blanket bogs in Western Europe.
Blanket bogs are wet, squelchy places where the peat forms from the remains of mosses and other plants in a layer typically 2-3 meters deep and supporting unique plants, animals and insects that are adapted to the water-logged ground.
Blanket bogs usually exist alongside other habitat types and on Cuilcagh, areas of heath are commonly mistaken for blanket bog as they contain many of the same types of plants and animals. Montane heath is an extremely rare type of heathland, found on the summit of Cuilcagh Mountain, which is one of only a handful of locations in Ireland.
Many streams and rivers flow off the upper slopes of Cuilcagh through the blanket bog and sink into the limestone carving out a network of hidden caves. The lower slopes of Cuilcagh are dominated by rare limestone grasslands that are awash with colour when wildflowers and herbs burst into life in the spring. Cuilcagh also supports a diverse range of animal, bird and insect life including the rare Golden Plover.