lEELAND 



385 



rust whicli covers it. According to the legend, the Giants' Causeway is the 

 remnant of a road which formerly led into Scotland, and, except that this 

 highway was not constructed by human hands, the legend is true. The 

 strait which now separates Ireland from Scotland, and which between Benmore 

 and the Mull of Kintyre has a width of only 14 miles, had no existence at the 

 time when the volcanic agencies were most active. The sheets of lava extended 

 then from shore to shore, just as the mountains of Donegal were connected 

 with those of Scotland, with which they agree in geological formation and 

 direction. Rathlin Island, which lies off the coast of Antrim, between Benmore 

 and the Giants' Causeway, is a remnant of this ancient bridge of lava, and the 

 cliflPs which bound it are formed of gigantic columns of basalt. It has been 



Fig. 194. — The Giants' Causeway and Eathlin Island. 

 Scale 1 : 250,ono. 



Over 110 

 Fathoms. 



2 Miles 



recently proposed to join, by means of a tunnel, the extreme point of Scotland at 

 the Mull of Kintyre to the Irish coast at Cushendun Bay. Such a tunnel would not 

 only be much shorter than that proposed for the Strait of Dover, but no danger 

 whatever could arise during its construction from an irruption of the sea. 



The most elevated mountains of the Ireland of to-day are far from piercing 

 the line of perennial snow, but there was a time when the whole of the country was 

 buried beneath a sheet of ice and snow. The volcanic rocks of Antrim, which are 

 partly covered with glacial drift, bear visible witness to the existence of glaciation, 

 and there is hardly a locality of Ireland which does not exhibit traces of the 

 ancient passage of glaciers. Boulder clay and gravels, erratic blocks, polished 

 rock surfaces, all tell the same tale— that the island formerly resembled Greenland. 

 The fine lines and groovings that mark the direction in which the ice sheets had 



