The most famous natural landmark in ------------------ is the Giant's Causeway. Comprised of approximately 37,000 dark basalt columns packed together, they were formed when a volcanic eruption spewed molten basalt out 55 million years ago. As the basalt cooled, these unique polygonal structures were formed. Most of the columns of the Giant's Causeway form a six-sided honeycomb pattern. Some have as many as ten sides and measure about 12 inches across and up to forty feet in length.?