Irish Volcanoes. 181 



of successive belts, consisting of lava perfectly loose and rotten, 

 of other lava singularly compact and durable, and of rotten and 

 altered vegetable matter or lignite, forming a kind of coal capa- 

 ble of being* used as fuel, but of very pure quality. There are 

 also beds of excellent and brilliant red ochre, and masses and 

 layers of lava full of a beautiful white semi-transparent crystal. 

 In the interstices of the harder rock, chiefly in the upper part 

 of the cliff, are found numerous beautiful specimens of agate, 

 chalcedony, and common opal, and occasionally jasper. All 

 these are identical with the stones of Lough Neagh, At and 

 near the foot commence those marvellously regular columns 

 that characterize the Causeway. A little to the left, in 

 descending (to the west of the Causeway), are the caverns. 

 Beyond, on each side, the white rocks peep out from under the 

 basalt. It is only on the east side, or between the Causeway 

 and the noble promontory of Fairhead, that the basalt is strictly 

 and regularly columnar, and indeed only a few cases occur 

 within these narrow limits. 



Most people when they first come upon the view of the 

 Causeway, of which they have probably both heard and read, 

 are a little disappointed at the smallness of the phenomenon. 

 The portion of the shore so called is only about three acres in 

 extent, and, contrasted with the extent of the coast line and 

 the space of sea visible, this is certainly not much. The 

 greatest length from the cliff to the low-water mark is about 

 220 yards, and the breadth is less than 120 yards. Within these 

 narrow limits, however, there is so strange and remarkable a 

 regularity in the rocks, they are so closely like artificial work 

 on a large scale, they exhibit such elegant forms and propor- 

 tions, and the result is so peculiar, and involves so great an 

 apparent repetition of like parts, that any one accustomed to 

 regard variety in detail as almost a law of nature, especially 

 in rocks and stones on a large scale, is unwilling to accept 

 the result. But everything resembling disappointment soon 

 dies away, and is succeeded by wonder, and a strong desire to 

 inquire into the probable cause of the phenomena. 



The visitor is at once made aware of the difference between 

 columnar basalt, 'and the comparatively irregular and shapeless 

 masses technically called amorphous basalt. The latter 

 abounds everywhere, and is what we have been already 

 describing as spread over the whole district. It is inter- 

 sected by scores of miles of coast. Along the whole line of 

 coast, however, and over the whole area, the columnar develop- 

 ment is rare and exceptional. The Causeway itself — those 

 columns in the little bay adjoining, called the Organ, about 

 midway up the cliff, and the two rows of columns called the 

 Plaskets, forming parts of a much more lofty cliff about two 



