BOTANICAL FEATURES OF IRELAND xvii 



gravel such as may be found on the low grounds which stretch 

 northward and westward. 



The Glacial deposits are thinner towards the west, and along the 

 Atlantic coast large areas are devoid of drift. In the metamorphic 

 and igneous districts, such as Connemara, the bog lies directly on 

 the gnarled rock, which continually breaks through the heathy 

 surface ; and only here and there a ridge or patch of Boulder-clay 

 produces an oasis of green pasture and crops. In the limestone 

 areas, the grey naked stone, fantastically carved by rain and per- 

 colating water, lies bare over hundreds of acres, its interstices filled 

 with the sweetest of grasses, and often with the rarest of flowers. 



The esker-ridges, which form so remarkable a feature of the 

 Central Plain, are, as stated above, composed chiefly of limestone 

 gravel, with occasional clayey layers and much clean sand. In their 

 characteristic form they are narrow and steep sided, Uke railway 

 embankments, and from 20 to over 100 feet high. Their course is 

 irregular, and often does not coincide with the present drainage- 

 lines of the country. Their grassy weU-drained sides form the 

 home of the few gravel-loving plants that haunt the Central Plain. 



The latest deposits of all are the bogs, which occupy no less 

 than 13-5 per cent, of the surface of Ireland. These bogs are of two 

 kinds — the black or mountain bogs, and the red or low-level bogs. 

 The former cover much of the surface of the mountain groups, and 

 along the bleak western coast extend over large areas at low eleva- 

 tions, descending actually into the sea. The red bogs are the more 

 interesting botanically. They spread over extensive tracts of the 

 Central Plain, resting on the Boulder-clay and lapping round the 

 flanks of the eskers. Owing to the continued growth of the plants 

 which form them, they rise above the general level of the surround- 

 ing country, like an inverted saucer on a table. They store up vast 

 quantities of water, and have a limited and characteristic flora. 



II. BOTANICAL FEATURES OF IRELAND. 



Total Flora. — The total flora of Ireland (Phanerogams and 

 Vascular Cryptogams : Characece not reckoned), on the standard 

 of Hooker's "Student's Flora of the British Isles" (1884), is set 



E.I.A. PKOC, SEE. III., VOL. VII. b 



