Presenter Caroline Nolan and Dr Ian Mitchell of the Geological Survey of Northern Ireland visit Ballycastle where they travel back 354 million years to when Northern Ireland was where the Bahamas are today.

This was the Carboniferous period and it was warm seas and blue skies for our land mass.

This warm, moist environment resulted in a landscape carpeted with lush vegetation and the appearance of the planet’s first rain forests.

On our landmass, this led to the development of huge damp forests containing tropical swamps, exotic plants, and towering tree canopies.

These were also home to amphibian-like reptiles and giant dragonflies (with wingspans of over 50cm), cockroaches over 10cm long and giant trees called Lepidodendron of 100 feet or more.

The rapid growth of vegetation within these hothouse conditions meant that a large amount of dead plant and tree life accumulated very quickly.

Over millions of years, as more and more vegetation got deposited, the pressure increased and the remains were compressed, driving gas and water out.

The result was the formation of coal.

Carboniferous meaning carbon, carbon meaning coal.

At one time, geologists say, much of Ireland would probably have been covered by coalfields.

In Northern Ireland, we only ever had two coalfields, in Coalisland in County Tyrone, and here in Ballycastle, County Antrim.

Ballycastle had enough coal to support a small-scale coal industry till the 1960s, and Ballycastle coalfield was regarded as the best exposure of a coalfield sequence in Ireland.