“Ages ago,” says Lord Dufferin, “some vast commotion shook the foundations of the island; and bubbling up from sources far away amid the inland hills, a fiery deluge must have rushed down between their ridges, until, escaping from the narrower gorges, it found space to spread itself into one broad sheet of molten stone over an entire district of country, reducing its varied surface to one vast blackened level. One of two things then occurred: either, the vitrified mass contracting as it cooled, the centre area of fifty square miles (the present plain of Thingvalla) burst asunder at either side from the adjoining plateau, and sinking down to its present level, left two parallel gjas, or chasms, which form its lateral boundaries, to mark the limits of the disruption; or else, while the pith or marrow of the lava was still in a fluid state, its upper surface became solid, and formed a roof, beneath which the molten stream flowed on to lower levels, leaving a vast cavern into which the upper crust subsequently plumped down.” In the lapse of years, the bottom of the Almannagja has become gradually filled up to an even surface, covered with the most beautiful turf, except where the river Oxeraa, bounding in a magnificent cataract from the higher plateau over the precipice, flows for a certain distance between its walls. At the foot of the fall the waters linger for a moment in a dark, deep, brimming pool, hemmed in by a circle of ruined rocks, in which anciently all women convicted of capital crimes were immediately drowned. Many a poor crone, accused of witchcraft, has thus ended her days in the Almannagja. As may easily be imagined, it is rather a nerve-trying task to descend into the chasm over a rugged lava-slope, where the least false step may prove fatal; but the Icelandic horses are so sure-footed that they can safely be trusted. From the bottom it is easy to distinguish on the one face marks and formations exactly corresponding, though at a different level, with those on the face opposite, and evidently showing that they once had dovetailed into each other, before the igneous mass was rent asunder.