300 MILLION YEARS AGO

In Central Europe another collisional event occurred towards the end of the Carboniferous (300 mya). The ORS and its overlying limestone were folded and thrust upwards into mountains. This was the Amorican fold belt which stretches from Dingle Bay to central Europe. The mountains of the Iveragh Peninsula as we know them today were formed during this uplifting. The ORS and its various formations were folded into upward and corresponding downward folds, anticlines and synclines.

The landscape of the geopark area reflects the fact that both the ORS and the carboniferous rocks were folded along east-west axes i.e. the whole lot were given a push from the south. Tension cracks in the rocks are visible on the beach at Derrynane at the southern end of the pier. These are uni-directional cracks in the sandstone rock which have been filled with white quartz. They demonstrate the pressure to which the rocks of the area were subjected during their formation. The cracks taper at both ends with the maximum yield directions perpendicular to these.

Folding and Faulting

Examples of folding and faulting in the rocks are common throughout the study area. A large dipping fold is clearly visible to the south from Coomacista car park. At Castlecove East a good example of a large fold structure can be seen from the main roadway (N70). The individual layers within the rock represent periods of stable and consistent formation while inter-layer periods represent some environmental changes. The entire study area consists of anticlinorial and synclinorial rock formations. This area at Castlecove East is an example of an anticline several hundred metres across.
About one third along the main road to the pier on Lamb's Head is found a good example of a fault. Even though these faults occurred hundreds of millions of years ago, they maintain a weakness in the rock formation which the sea erodes forming a cave or a bay as a result. Caves and inlets, large and small found along the study area coastline frequently owe their origins to faulting.

Metalliferous ores were formed along the joint and fault planes during this Amorican folding period and include deposits of copper such as those found on Coad Mountain and Valentia Island. They are often accompanied by quartz, which is highly visible in the rock face and especially evident at Coad

After the mountains of ORS covered by carboniferous limestone had been raised, a prolonged period of weathering followed which resulted in the gradual erosion of the less resistant limestone. Limestone in the region is now confined to a narrow coastal strip between Kenmare and Blackwater Bridge.