In the first place, the phenomenon of the edges of the great glacier region of Lang Jökull rising above the centre, makes it possible that towards that centre there may be a considerable depression. Next, the stone asserted to have been set up by Grettir on Skjaldbreid still stands, but has fallen out of the perpendicular, so that the hole in it does not point to any opening in the glaciers; but a little to the right appears a small ravine between piles of ice, through which runs a small river, which shortly after enters a lake, and, after having fed two other lakes, finally enters the Tungafljot, and flows past the geysers. And once more, throughout Iceland, the junction of the trap and trachyte is marked by boiling jetters; so that the mention of the hot-springs in the _Gretla_ is quite in accordance with what the geological structure of Thorir’s Head would lead us to expect. The suspicious portion of the account is the mention of Thorir and his daughters; but in all probability this Troll was nothing more than an outlaw, like Grettir himself, and, indeed, Hallmund, who is alluded to as having given Grettir his direction to the valley, and who was a personal friend of Grettir’s, and an outlaw, is called a Troll in the Barda Saga, which speaks of him and the Thorir of the mysterious vale. It is a curious fact that, in the south-east of the island, in the Vatna Jökull, a tract very similar in character to Lang Jökull, but on a far larger scale, is a valley full of grass and flowers and glistening birch, completely enclosed by glaciers, which sweep down on this little fairy dell from all sides, leaving only one narrow rift for the escape of the water, and as a portal to the glen. The expedition of Messrs. Olafsen and Povelsen is given in their own words. “On the 9th of August we started from Reykholtsdal on our way to the glacier of Geitland; our object was not so much to discover a region and inhabitants different from those we had quitted, as to observe the glacier with the most scrupulous accuracy, and thus to procure new intelligence relative to the construction of this wonderful natural edifice. The weather was fine and the sky clear, so that we had reason to expect that we should accomplish our object according to our wish, but it is necessary to state that in a short time the Jökulls attract the fogs and clouds that are near. On the 10th of August in the morning the air was calm, but the atmosphere was so loaded with mist that at times the glacier was not visible. About eleven o’clock, however, it cleared up, and we continued our journey from Kalmanstúnga.