Giant's Causeway with higher saline content than that found at the causeway. Although the basaltic columns of the Giant's Causeway are impressive, they are not unique. Basalt columns are a common volcanic feature, and they occur on many scales (because faster cooling produces smaller columns). The Belfast-Derry railway line run by Northern Ireland Railways connects to Coleraine and along the Coleraine-Portrush branch line to Portrush. Local Ulsterbus provide connections to the railway stations. There is a scenic walk of 7 miles from Portrush alongside Dunluce Castle and the Giant's Causeway and Bushmills Railway. Giant's Causeway The Giant's Causeway is an area of
Cave of the Crystals the Naica mine workings, the Cave of Swords (). It is located at a depth of , above the Cave of the Crystals, and contains spectacular, smaller ( long) crystals. It is speculated that at this level, transition temperatures may have fallen much more rapidly, leading to an end in the growth of the crystals. Giant Crystal Cave was discovered in April 2000 by miners excavating a new tunnel for the Industrias Peñoles mining company located in Naica, Mexico, while drilling through the Naica fault, which they were concerned would flood the mine. The mining complex in Naica contains substantial