Around 420 million years ago the entire Iapetus Ocean disappeared completely, and during this closure the continents on either side began to move closer and closer together.

The edges of Ireland north and south were sitting right on the perimeter of these continents and the effect was extraordinary.

Over a period of many millions of years these ancient landmasses merged via a complex series of collisions.

These are imprinted on our landscape often as major fault lines or fold belts.

Imagine two cars hurtling toward each other, when they slam together the bonnets crumple and concertina - this type of pressure on the rock during this continental collision thrust up an entire new range of mountains.

Extending from Norway through northern Scotland and into north-west Ireland, as well as across into what is now Newfoundland and Nova Scotia in eastern Canada, the Caledonian Mountains were created during this long period of collision.

On the island of Ireland they comprise the Sperrin Mountains of Derry and Tyrone, the highlands of Donegal, and the mountains of Mayo and Connemara.

But today, mountains like the Sperrins are evidently not the height of the Himalayas.

That is simply because of erosion.

Over the next 390 million years the mountains would be eroded away, so what we see now are just the roots of this once massive chain.

But given that their sheer height and length, it is not surprising that the Caledonian Mountains would dominate and influence our landscape until the Carboniferous period some 75 million years later.