A Journey Through
Deep Time
Geology is an Earth science, however, here at Cuilcagh Lakelands Geopark, Geology is so much more. It is the greatest historian, the most captivating storyteller and the guardian of a time long forgotten. With each different rock-type that is discovered and explored within the Geopark, a new and exciting story is revealed about our history, our environment and our world.
Let’s go right back to when our story first began.
Quaternary
13,000 years ago
The Big Freeze
The single biggest impact on the landscape of the Geopark comes from the last glaciation. Huge ice sheets scoured out the glacial valley of Lower Lough Erne and sculpted the ribbed moraines of Lough Oughter. When the ice finally melted about 15,000 years ago it left behind boulders, moraines and glacial till — seen today in Cavan Burren Park, Slieve Rushen and Lough Navar Forest.
Neogene
2.6–23 million years ago
Cooling Towards the Ice
Ireland had reached its modern position and the climate was gradually cooling. The landscape was being slowly shaped by erosion and rivers, setting the scene for the dramatic glacial forces that would transform the Geopark in the period that followed.
Paleogene
65 million years ago
A New Ocean
As plate tectonic activity caused North America to pull apart from Europe, the crust stretched and thinned generating huge amounts of molten rock beneath the surface. Whilst there is no evidence of volcanoes in the Geopark, dykes — vertical sheets of igneous rock — formed as magma squeezed into cracks in the existing rocks. They can be seen at Gortmaconnell in Cuilcagh Mountain Park, Cavan Burren Park and Aghameelan in Lough Navar Forest.
Cretaceous
66–145 million years ago
Still No Record
The rock record within the Geopark remains absent through the Cretaceous period. The next chapter of the Geopark’s story only begins when volcanic activity dramatically returned to reshape Ireland 65 million years ago.
Jurassic
145–201 million years ago
A Missing Chapter
The Jurassic left no trace in the rock record of the Geopark. While warm shallow seas covered much of Europe and dinosaurs roamed the land, Ireland’s story from this time has been lost completely. The booklet notes there is no evidence of any rocks in the area from 320 million years ago until 65 million years ago.
Triassic
201–252 million years ago
A Vanishing Record
No rocks from the Triassic period survive within the Cuilcagh Lakelands Geopark. Ireland drifted northwards through sub-tropical latitudes as part of Pangaea, but this chapter of the story has been entirely lost to erosion and time.
Permian
252–299 million years ago
A Gap in the Record
The rock record of the Geopark falls silent for this period. No rocks from this time have survived within the area. Ireland continued northwards through hot desert conditions as part of the ancient supercontinent Pangaea, but the evidence of this chapter has long since been eroded away.
Carboniferous
299–359 million years ago
Tropical Ireland / Deltas and Coal Swamps
Ireland reached the equator around 340 million years ago, submerged beneath a shallow tropical sea. The lime-rich mud compacted over millions of years to form limestone — the rock that makes up the majority of the Geopark today, shaping the slopes of Cuilcagh Mountain and forming the caves of Marble Arch. As sea levels later fell, vast river deltas deposited the sandstone now forming the summits of Belmore, Ballintempo and Slieve Rushen, while dense tropical forests eventually turned to coal.
Devonian
359–419 million years ago
Searing Hot Deserts
By about 400 million years ago Ireland was about 20° south of the equator, at desert latitudes similar to the Sahara Desert. The very arid conditions led to the deposition of red sandstones, some of which can still be seen on the shores of Lower Lough Erne within Castle Archdale Forest.
Silurian
419–444 million years ago
Mountain Building
The closure of the Iapetus Ocean created a colossal mountain range to the north of the Geopark that would have been even higher than the Himalayas, forming what we now know as the Donegal Highlands and the Sperrin Mountains. The enormous heat generated also produced vast amounts of magma — seen today as granite in the small quarry at Crossdoney.
Ordovician
444–485 million years ago
Vanishing Oceans
About 500 million years ago, the vast Iapetus Ocean began to close as plate tectonic activity drew the two continents slowly together. Remnants of this ancient ocean can still be seen as mudstones and sandstones on the southern shores of Lough Oughter near Killeshandra and at Bruse Hill near Arva, formed from sediments carried to the ocean floor around 450 million years ago.
Cambrian
485–541 million years ago
An Ancient Ocean Awakens
Ireland did not yet exist as a single island. Two separate landmasses lay far apart in the southern hemisphere, divided by the vast Iapetus Ocean teeming with early marine life. The rocks that formed on this ancient ocean floor would eventually carry the story of two worlds slowly drifting towards each other.
Pre-Cambrian
895 million years ago
Ancient Foundations
The oldest rocks of the Geopark are found on the northern shores of Lower Lough Erne. These rocks are thought to be nearly 900 million years old and would have most likely started out as sandstones. Since they were deposited they have been subjected to intense heat and pressure that has metamorphosed them into a rock called gneiss (pronounced nice).