How was the Giant's causeway made?

The Giants Causeway stretches from Ireland to Scotland. 60 million years ago lava from eruptions cooled in contact with air and rock, hardening into basalt. Thousands of years later more lava erupted and cooled slowly and evenly in a deep pool. Cracks travelled through the cooling rock, creating the columns and making the honeycomb pattern we can see today. There are over 40,000 columns at the Giant's Causeway, most are six-sided, but there are others with fewer or more sides. Later eruptions left these columns hidden deep underground. It took millions of years of erosion for the columns to begin to be revealed and changes in sea levels for the current formations to be seen.