Giant's Causeway Geology
Research Geologist, Daniel Muhs, got a chance to visit Giant's Causeway in Northern Ireland after presenting his research at the International Quaternary Association meeting in Dublin.
Shown in the photo are the tops of basalt columns. Basalt is a volcanic rock and these volcanic flows are about 62-63 million years old. Erosion has planed off the tops of the columns here, nearly to sea level, giving the quasi-circular pattern seen in the picture.
The volcanic basalt formed here as a result of molten (liquid) mantle material to come to the surface, cooling, and solidifying as rock. The process was going on as the Mid-Atlantic Ridge was pushing North America and Europe apart and forming what is now the north Atlantic Ocean. Although this basalt has been solid rock now for tens of millions of years, the same process continues today on the Mid-Atlantic Ridge, in Iceland, which is also composed dominantly of basalt, but is much younger.
Giant's Causeway is one of the most spectacular geologic sights in Europe. More than a million people visited this site in 2018. Its scenic beauty and geologic significance is so great that it has been designated as a UNESCO World Heritage Site.