Physical Geography.—Ireland stands on the edge of the European “continental shelf.” Off the peninsula of Mullet (county Mayo) there are 100 fathoms of water within 25 m.of the coast which overlooks the Atlantic; eastward, northward and southward, in the narrow seas, this depth is never reached.
On many of these desolate rocks, which could have afforded only the barest sustenance, there are remains of the dwellings and churches of early religious settlers who sought solitude here.The settlements on Inishmurray (Sligo), Aranmore in the South Arans, and Scattery in the Shannon estuary, had a fame as retreats of piety and learning far outside Ireland itself, and the significance of a pilgrimage to their sites is not yet wholly forgotten among the peasantry, while the preservation of their remains has come to be a national trust.Thence over the whole southward stretch to Mizen Head in county Cork is found that physical appearance of a cliff-bound coast fretted with deep fjord-like inlets and fringed with many islands, which throughout the world is almost wholly confined to western seaboards.Mountains impinge upon the sea almost over the whole length, sometimes, as in Slieve League (county Donegal), immediately facing it with huge cliffs. Lough Foyle is divided from Lough Swilly by the diamond-shaped peninsula of Inishowen.The islands though numerous are not as in Scotland and Norway a dominant feature of the coast, being generally small and often mere clusters of reefs.
Exceptions, however, are Tory Island and North Aran off the Donegal coast, Achill and Clare off Mayo, the South Arans guarding Galway Bay, the Blasquets and Valencia off the Kerry coast.The principal groups, with their highest points, are the Mournes (Slieve Donard, 2796 ft.) and the Wicklow mountains (Lugnaquilla, 3039) on the east; the Sperrins (Sawel, 2240) in the north; the Derryveagh group in the north-west (Errigal, 2466); the many groups or short ranges of Sligo, Mayo and Galway (reaching 1695 ft.in the Twelve Pins of Connemara); in the south-west those of Kerry and Cork, where in Carrantuohill or Carntual (3414) the famous Macgillicuddy Reeks which beautify the environs of Killarney include the highest point in the island; and north-east from these, the Galtees of Tipperary (3018) and Slieve Bloom, the farthest inland of the important groups.(c) Connaught (western midlands): Counties Galway, Leitrim, Mayo, Roscommon, Sligo.(d) Munster (south-western division): Counties Clare, Cork, Kerry, Limerick, Tipperary, Waterford.Turning northward to the east of Waterford round Carnsore Point, the lagoon-like harbour of Wexford is passed, and then a sweeping, almost unbroken, line continues to Dublin Bay.