Giant's Causeway

a noted rock formation on the north coast of Ireland. The "causeway" is a tract of basaltic columns laid bare by the waves. Tourists make their way for a long distance on an uneven floor, walking on the upper ends of 40,000 upright, six-sided columns that stand side by side like the trunks of trees. This basaltic outflow is part of the formation in which Fingal's Cave has been worn by wave action. In cooling the basalt simply cracked into regular six-sided columns instead of into the irregular cakes to be seen at the former bottom of a dried out mud puddle. See Fingal'S Cave; Basalt; Cave