Stratigraphicac Geology. 6/ 



existence of a subterranean channel which drains the lake 

 into the Carey river. 



In County Down a few lakes are to be found among the 

 Mourne mountains. These lakes are dammed by moraine 

 material, and evidently originated in the Glacial period. 

 Numerous small lakes occur on the low grounds. 



Islands. 

 The most important island off the Antrim coast is Rath- 

 lin — called by the natives Raghery ; it figures on Ptolemy's 

 map as Rechra. It is about six miles north of Ballycastle, 

 and, geologically, is similar to the mainland of Antrim, 

 which it also resembles in scenery : it contains about 

 3,400 acres. Between this island and the mainland a 

 strong tide runs. This stretch of w-ater was known as the 

 " Moyle," and is referred to in an old Irish legend, and in 

 Moore's well-known lines : 



" Silent, O Moyle, be the roar of thy waters." 



Off the coast of Down and in Strangford Lough are a 

 number of islands of small size. The most noted are the 

 Copeland Islands, off the north-east of Down. 



STRATIGRAPHICAL GEOLOGY. 



WE may claim for our district, with a considerable 

 amount of justice, that it presents to the geologist, 

 within its small area, a great variety of remarkable 

 features and rock exposures which will prove well worthy 

 of detailed study. 



We find in our counties representatives of the four great 

 eras. The Archcean period is possibly represented by the 

 schists and gneisses of north east Antrim ; the Palaeozoic era 

 is represented by the Ordovician and Silurian rocks of 

 County Down, by the Old Red Sandstone near Cushendall, 

 by an interesting patch of Carboniferous sandstone near 

 liallycastle, County Antrim, and by Carboniferous shales 

 near Piclfast. Just beyond the boundaries of our district 

 Carboniferous limestones are found at Carlingford and in 

 County Tyrone. 



