Giant’s Causeway (Part 2): Other volcanic highlights

Dr Trevor Watts (UK) This is the second and final part of an article on the volcanic highlights of Northern Ireland’s Giant’s Causeway and surrounds. For the first part, see Giant’s Causeway (Part 1): An introduction.) We were in the area for several days and the weather was fairly mixed, but there were glorious skies between the showers, and the high winds brought the waves up beautifully. Of the six highlights discussed below, we visited the first three in one day, as all were a few kilometres to the west of The Giant’s Causeway. Those to the east, we visited on another day. Fig. 1. A map of some of the highlights. They are all supremely interesting and give an idea of the range of volcanic features to be seen. You cannot see an actual, traditional volcano in Antrim, with its classic shape. However, you can visit many scattered and varied elements of the area’s vulcanicity, and so gain an appreciation of the overall picture. Fig. 2. Fanciful cross section of highlights. 1. Deep lava flows forming the Causeway Basalts and their columnar basalt features. Found at The Giant’s Causeway and Ballintoy Harbour. 2. Beds of red ‘laterite’ rocks and soils buried by the later lava flows. Seen along the whole coast, especially east of the Giant’s Causeway. 3. Multiple relatively thin lava flows forming the Lower Basaltic Series. Seen at The Giant’s Causeway area and Dunluce Castle. 4. Dykes bringing magma towards the surface through fissures of cracks in … Read More

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Giant’s Causeway (Part 1): An introduction

Dr Trevor Watts (UK) This is the first of two articles on the volcanicity of the Giant’s Causeway and the surrounding area. The Causeway itself is an area of basalt columns, about 100m or so across, jutting into the Irish Sea. A remnant of a vast ancient lava flow, it is located in a coastal strip that is lavishly scattered with other superb volcanic features. The whole area is both beautiful and fascinating, and neither spoilt in any way, nor over-crowded out of season. We (my wife Chris and I) went there because I had a few days’ work in Northern Ireland and it seemed like a good idea to combine this with a short break during an October, half-term school holiday. Fig. 1. The Giant’s Causeway, battered by curling waves, becomes a sunlit wonderland in the evening light of autumn. The geology of the Giant’s Causeway The long-held theory that the Causeway was created by an Irish giant called Finn MacCool in Middle Earth times has – sadly – been discredited. Around 60mya (in early Tertiary times), great masses of molten rock were rising from the depth of the earth’s mantle, probably centred beneath present-day Greenland. These nation-sized ‘lava-lamps’ are collectively considered to be a ‘hot spot’, now known as the ‘Iceland Plume’. They split the earth-wide continent of Pangaea apart in great cracks that were aligned roughly northwest to southeast. This was sufficient to split the land apart on a vast scale, beginning the opening of the Atlantic … Read More

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