First, then, how can we make sure that no convulsion of nature has produced a rent in the rocks, and so helped the streamlet to a channel? a simple question that may be well-nigh as simply answered. We stand in the centre of the dell on a broad ledge of stone, round whose well-worn sides the rivulet is ever eddying onwards. The block consists of a pale sandstone lying in a bed about three feet thick, that dips gently down the stream and underlies a seam of dull, soft, blue shale, full of small shells. We trace the edge of this sandstone bed across to the left-hand side of the ravine, and away up into the precipitous cliff, till it is lost amid the ferns and brushwood. There can be no doubt, therefore, that the ledge on which we were but now standing is a continuous portion of the rocks that form the left side of the ravine. Returning again to the centre of the stream, we proceed to trace out the course of the other end of the same bed, and find that it, too, strikes across to the rocks on the right-hand side without a break or fissure, and passes up into the cliff, of which it forms a part. Clearly, then, the sandstone bed runs in an unbroken, unfissured line, from the one side to the other, and the rocks of either cliff form one continuous series. There occurs no break or dislocation, which, of course, there must have been had the ravine owed its origin to any subterranean agency. And so we come to conclude that no great cataclysm in primeval times, no yawning abyss, or gaping chasm, has had anything whatever to do with the formation of our deep sequestered dell. What then? "Whither shall we turn," you ask, "to find another agency equally grand and powerful in its operation and mighty in its results?"