From the summit of the pass an extensive view of the _Mývatns Öraefa_, Desolate Lava of _Mývatn_, is obtained towards the northeast. It is a trackless ruin wrought by the combined labors of several volcanoes and contains no vegetation save patches of lichens that nourish a small herd of reindeer. At the foot of the slope upon which we halted a vast plain spreads out into the _Öraefa_. This plain is covered with a thin crust of chemical earths which rest upon a substratum of viscid, hot and sulfur-permeated clay. At the margin we left the ponies and ventured cautiously upon the crust, recalling the experience of Dr. Hooker in a similar situation at _Krisuvik_, where he nearly lost his life by sinking into the hot mass. The crust will support the curious traveller if he is sufficiently cautious in choosing his route by sounding the shell in front of him with a staff. It reminded me of an experience I had when a boy in watching my father cross a river upon thin ice, where he sounded the ice step by step in advance with the pole of his axe while I followed with great temerity over the cracking ice. As I expressed my fear of breaking through, he replied, “it will hold as long as it cracks.” And so with the sulfur crust above the seething furies, “it will hold as long as it cracks.” Woe to him who fails to sound this undulating crust before his advancing steps! All of this crust is composed of sublimated chemicals brought to the surface by the superheated gases. The crystals are various in form according to their chemical constituents and together they present a discordant color scheme, much like a painter’s palette where the various color daubs have run together. As one crunches the crystals beneath his feet he has the sensation of walking with hob-nails through a jeweller’s showcase.