The lakes of Ireland (called loughs) are, as might be expected from the surface character of the country, both numerous and extensive in proportion to tbe size of the island. The largest is lough Neagh in Ulster, covering an area of 100,000 acres. The other loughs of consequence are loughs Erne and Derg, also in•Ulster; Conn, Mask, and Corrib, in Connaught; the Allen, Ree, and Derg, which are expansions of the river Shannon, and the lakes of Killarney (q.v.) in Kerry.—The bays and salt-water loughs which indent the island are also numerous and of considerable importance. About 70 are suitable for the ordinary purposes of commerce; and there are 14 in which the largest men-of-war may ride in safety. The principal are loughs Foyle and Swilly, on the n. coast; the bays of Donegal, Sligo, Clew, and Galway, the estuary of the Shannon, Dingle bay, and Bantry bay, on the w.; the harbors of Cork and Waterford, on the s.; Wexford harbor, the bays of Dublin, Drogheda, and Dundalk, and loughs Carlingford, Straugford, and Belfast, on the east.—The islands are, generally speaking, small and of little importance. On the e. coast the largest is Lambay, about 2i in. off the coast of Dublin; on the s. and s.e. coasts are Clear island, the Saltees, a dangerous group of islets, about 8 in. s. of the Wexford coast, indicated by a floating light, and Tuscar rock, about 8 m. c. of Carnsore point, also a dangerous ledge, rising 20 ft. above the sea, and surmounted by a light-house after the model of the Eddystone; on the w. coast. the Skelligs, Valentia, the Blaskets, the South Arran isles, Innisbofin, Innisturk, and Clare, Achil or " Eagle" island, and the Inniskea islets; on the n. coast, the North Arran isles, the Tory isles, and Bairiki.
great series of grits and slates of Cambrian age occur in the s.e. of Ire land; the upper portion contains a few fossils of zoophytes and worms. Lower silurian strata rest unconformably on the Cambrian rocks in the same district. They consist of flags, slates, and grits ninny thousand feet in thickness, extending over large portions of Kildare, Wicklow, Wexford, and Wat•ford. Several detached patches occur to the w, of this district, forming the Keeper, Arra, and Inchiquin mountains. A tract of similar beds stretches from the center of Leland, near the source of the Shannon, to the coast of Down. The strata, in proximity to the Wicklow and Dublin granites are converted into gneiss and mica-slate. This is the condition of all the beds in the.n.w., in Donegal, Tyrone, and Mayo; they appear to be a continuation of the highly altered strata of n. of Scotland. Detached portions of upper silurian measures occur on the western side of the island, in Kerry, Galway, and Mayo.
Between the silurian and old red sandstone is an enormous thickness (11,000 ft.) of sandstone grit and shale in Kerry'and Cork. These strata are almost wholly unfossi li fermis.
Old red sandstone strata, consisting of red and yellow sandstone and slate, a large tract of the s. of Ireland, stretching almost continuously from the extreme w. of Cork and Kerry into Waterford and Kilkenny, stopped by the silurian rocks of Wexford and Carlow. Along the bases of the Millman mountains of the s, center of Ireland, and in the southern portion of the county of Cork, occurs a great thickness of sandstones, which have hitherto yielded no fossils; some geologists refer these to the old red series, others hold them to be lower carboniferous.
The carboniferous limestone is extensively developed in Ireland, occupying the whole of the center of the country, except in those places already allndeno, where the older rocks appear on the surface. This great tract is an extensive plain covered with drift,
and with peat-moss and fresh-water marl, in which are found the remains of Megaceros hibernicus and boa longifrons. In Kerry, Cork, and Waterford the strata are very much contorted, the coal-seams are changed into anthracite, and so squeezed and crushed as to be got only in small dice-like fragments. Further n. the strata are nearly horizontal, but the coal-fields are limited, and the seams are generally of inconsiderable thickness. They occur chiefly in Tipperary, Kilkenny, Tyrone, and Antrim.
Small deposits of Permian strata are found at Ardtrea in Tyrone, and at Cultra near Belfast; the sandstones of Roan hill near Dungannon are probably of the same age. The red and variegated marls containing beds of gypsum and rock-salt, which exist on the coast n. from Belfast, are probably triassie. Resting on these marls are a few thin beds of lies. Cretaceous strata occur in Antrim and Derry.
the climate of Ireland bears, as might have been expected, a strong resemblance to that of Great Britain (q.v.), it has yet a character peculiar to itself, owing to the marked difference in the configuration of its surface, its greater distance from the continent of Europe, and its being, as it were, more completely bathed in the warm waters of the gulf-stream. The mean annual temperature of the central parts of the country is about 50°.0, rising in the s. to 51°.5, and falling in the n. to 48°.5. There are thus of difference between the extreme n. and s., and it may be noted that, speaking generally, this differenceis constant through all the seasons of the year. The mean temperature in winter is 41°.5; in spring, 47'.0; in summer, 60'.0; and in autumn, The annual rainfall averages from 25 to 28 in., except in the neighborhood of hills, where the precipitation is considerably augmented; thus, at Valentia, in Kerry, the rain fall of 1861 amounted to 73 in., and doubtless this large fall was greatly exceeded in those parts which are situated among the higher bills. The rainfall in winter, particu larly in the w., is greatly in excess of the other seasons, owing to the low temperature of the surface of the ground during winter, which suddenly chills the warm and moist s.w. winds that prevail, especially at this time of the year, and condenses their vapor into rain. Since in Great Britain the chief mountain ranges are in the w., it follows that over the whole eastern slope of the island the climate is dryer, the amount and trequency of the rainfall much less, and the sunshine more brilliant than in the west. In Ireland, on the other hand, the hills in the w. do not oppose such a continuous barrier to the onward progress of the s.w. winds, but are more broken up and distributed in isolated groups. It follows that the sky is more clouded, and rain falls more frequently in Ireland, and the climate is thus rendered more genial and fostering to vegetation; hence the appropri ateness of the name " Emerald Isle." Again, owing to its greater distance from the con tinent, the and noxious e. winds of spring are less severely felt in Ireland, because the n.e. winds have acquired more warmth and moisture in their progress. It is on this account that the most salubrious spring climates possessed by England, Scotland, and Ireland are situated in the s.w of their respective countries. Thus, Queenstown, in the s.w. of Ireland, enjoys an average spring temperature as high as 50`.0, which is about the highest in the British islands, and nearly higher than the e. of Kent, which is nearly in the same latitude.