The Physical Geology and Geography of Ireland; With Two Coloured Maps and Twenty-Nine Illustrations

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1891 Excerpt: ...and Derry; (2) the Western Highlands of Mayo and Galway including Connemara; (3) the South-Western Highlands of Kerry and Cork, with the outlying elevations of Maugherslieve, the Devil's Bit, Slievenaman, Knockmealdown and Galtymore, which all physically belong to this group; (4) the SouthEastern Highlands of Wicklow and Dublin; and (5) the North-Eastern Highlands of Mourne, Carlingford, and Slieve Gullion. Besides these there are, of course, many minor hills, variously composed, and of different ages, which are not of sufficient magnitude to entitle them to rank as mountains; though it must be confessed that it is often difficult to say where the 'hill' merges into the 'mountain, ' and, conversely, where the mountain merges into the hill. I have already given some account of the geo CHAPTER II NORTH-WESTERN AND WESTERN HIGHLANDS In searching amongst the groups I have named above for the most ancient, we naturally refer to the formation of greatest antiquity, and we find ourselves amongst the north-western, the western, and the south-eastern Highlands, formed, as I have already shown (p. 12), of Lower Silurian beds generally converted into crystalline schists, quartzites, and gneiss by that deep-seated hydrothermal and dynamic process which we call' metamorphism.' I have already shown that the metamorphic rocks of Donegal, Mayo, and Galway belong to one great geological system continuous with that of the Central Highlands of Scotland, and that the epoch at which this transformation of the original strata took place is accurately determined for us by the position of the Upper Silurian rocks on both sides of Killary Harbour, and in the direction of Lough Mask.1 Here it is that, the Upper Llandovery beds, consisting of red and grey shales, grits, and cong...