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miles. The western extremity of Rathlin, called Bull Point, 

 looks away to the Atlantic Ocean, while the eastern side faces 

 Cantyre in Scotland, distant about fourteen miles. Tne island 

 presents steep escarpments to the sea throughout nearly the 

 entire extent of its coast line, Church Bay, opposite to Bally- 

 castle, being the only exception of any consequence. At the 

 south or Ushet end the cliffs are comparatively low, but they 

 rise steadily to the north and west until they attain an altitude 

 of 300 to 400 feet. The geological structure of the country is 

 simple, but nevertheless possesses many points of interest ; and 

 the cliffs afford the very best sections for this study. Two 

 classes of rocks are developed — the igneous and the sedimen- 

 tary. The stratified rocks consist of the white limestone of the 

 cretaceous series, and differ in no way from the white rocks so 

 conspicuous on the Antrim coast. The igneous rocks consist of 

 several varieties of trap, in some cases hard and compact, in 

 others amygdaloidal. Ash beds of considerable thickness are 

 to be seen at the north-east. Iron is an important constituent 

 of these rocks, some of the sections being coloured by the red 

 oxide. In several places at the south-east a columnar structure 

 is developed like that at the Giant's Causeway. Though the 

 pillars are often quite regular, yet the peculiar horizontal 

 jointing so beautifully displayed at the Causeway is here only 

 a subordidate feature, or exists in an imperfect form. Dr. 

 Hamilton stated that the Ballycastle coalfield extends to Rath- 

 lin, but I could not discover the coal-measure rocks any- 

 where. 



By reason of the isolation of Rathlin, its natural history 

 possesses more interest than that of a similar area on the main- 

 land. In such a place we expect to find only the really native 

 animals and plants : the indigenous fauna and flora of the 

 country, venerable by reason of antiquity, and cut off to a great 

 extent from the immigration of strangers. This is well seen in 

 Rathlin. Thus the common frog, an importation to Ireland 

 of recent time, has not yet made its way into the island, though 

 so abundant on the mainland a few miles off. And the same 

 is true of the water thyme {Anacharis), which is not to be 



