That little cake of grit on the top of Slieve League stands as a monument of waste so prolonged and so stupendous as to be hardly conceivable. It proves that the north-west of Ireland was buried under a sheet of strata many hundreds of feet thick, and that, inch by inch, this overlying mantle of solid stone has been worn away, until it has been reduced at last to merely a few scattered patches of which that of Slieve League is the most westerly. Not only so, but the present system of hill and valley is thus demonstrated not to be part of the primeval architecture of the earth, but to have come into being after that upper envelope of Carboniferous rock had begun to be removed. What a marvellous series of pictures is thus presented to our imagination! Standing on that bare mountain-top, we think of the ages represented by the quartzite of those craggy precipices below, then of the time when the region lay beneath the waters in which the coal jungles spread over a large part of Ireland. We try to realise how these jungles sank foot by foot beneath the sea, how sand and silt were heaped over them, and how, in course of ages, this submerged area was once more upraised into land. But we fail to form any adequate conception of the lapse of time required for the long succession of changes that followed. We only know that, slowly and insensibly, by the fall of rain, the beating of wind, the creeping of ice-fields, and the surging of the ocean, hollow and glen have been carved out, hill after hill has emerged, like forms from a block of marble under the hand of a sculptor, that ravines have been cut out here and crags have been left there, until, at last, the whole landscape has been wrought into its present forms. We look once more down the face of the precipice, now lit up by the advancing sun, and, though everywhere upon its ruined surface we mark how-- 'Nature softening and concealing, Is busy with a hand of healing'-- crusting the bare rock with golden lichen, or hiding its rawness under a cover of richly tinted weather-stains, we none the less perceive the sure signs of constant and inevitable decay; we recognise the working of the same forces that have sculptured the whole landscape, far as well as near; and we feel awed in presence of this revelation of the continuity of law and of the potency even of the unregarded operations of nature when they have had untold ages in which to accomplish their appointed work.