Land of Fire

The uppermost layer of the Belfast Hills ‘cake’ is similar to the icing in that it is the most dramatic layer. Following on from a mass extinction, the beginning of the Palaeogene (also known as the early part of the Tertiary) period was literally explosive! The continent of North America was moving away from Europe and the resulting tearing and stretching led to widespread volcanic activity, the evidence of which is beautifully preserved all the way across the Belfast Hills.


The tearing of the Earth’s crust created linear eruptions or fissures up through which lava spewed out and covered the entire landscape. It is these successive flows of lava that make up the layers of basalt of the upper most escarpment of the Belfast Hills. In other cases, the volcanic eruptions were from a single volcano and the remains of these volcanic plugscan be seen dotted across the landscape.


This fiery landscape with violent eruptions and the accompanying earthquakes that shook the entire area is hard to imagine. However, it is because of this violent past that the Belfast Hills exist, as the resulting basalt that formed as the lava cooled has acted as a protective barrier to the underlying rocks. It has also had the added effect of ‘cooking’ the white limestone beneath making it harder than its counterparts elsewhere.


The best places to see the Palaeogene rocks are Belshaw’s Quarry, Cave Hill Country Park, Divis Mountain, and Carnmoney Hill.


Find Palaeogene rocks at:

CaveHill Divis Carnmoney


Geology Timeline:

Go BACK to the Cretaceous Period Go FORWARD to the Pleistocene Period
Shallow Tropical Sea Thumbnail Pleistocene Period Thumbnail Svalbard