More definite information concerning the volcanic activity of Iceland reached Saxo Grammaticus about a century after the time of Adam of Bremen. Saxo refers to a mountain there which perpetually glows like a star with its burning flame, and it seemed to him no less marvelous that the eruption could occur in a region of such extreme cold.[1020] In the _Historia Norwegiae_ the fiery outbreaks of Mons Casule (Hekla) are likened to those of Etna, and an immense submarine eruption is described; over a space three miles wide the sea had boiled and bubbled as in a caldron; the earth was upheaved and out of the submarine depths there arose fiery fumes, and a mighty mountain sprang from the sea.[1021] This perhaps refers to a submarine eruption that took place off Cape Reykyanes in 1211.[1022] In the _King’s Mirror_ the volcanic activity of Iceland is compared with that of Sicily, and the curious statement is made that, unlike the subterranean fires of the Mediterranean isle, those of Iceland will burn neither wood nor earth. On the other hand, they will burn the hardest stones and pieces of rock just as easily as oil.[1023] ST. BRANDAN’S VISITS TO VOLCANIC ISLES St. Brandan in the course of his wanderings came across two fiery islands.[1024] The first was eight days’ sail to the north of the mysterious crystal column we have already mentioned. It was a rough, treeless, and rocky isle covered with the forges of smiths. Though the saint wished to keep clear of this dangerous spot, a wind sprang up which drove his vessel towards it. One of the smiths threw a gigantic mass of molten slag at the voyagers; but luckily he missed the ship, and the slag fell into the sea, sending up huge clouds of steam. This was a signal for all the smiths to start heaving lumps of molten ore at the vessel, running back and forth from their forges to heat them. Soon the entire island was burning and blazing like a furnace, and the sea around boiling like a kettle. The saint and his party miraculously escaped from this peril, but throughout the entire day they could hear an immense din and shouting from the isle; and even when they had drifted out of sight the tumult came to their ears, and their nostrils were afflicted by a terrible stench. Soon the wanderers approached the second fiery isle; their first sight of it revealed a mighty mountain on the northern horizon, with its peak enveloped in what appeared to be a thin cloud but in reality was smoke. They landed on the shores of the island, and one of Brandan’s companions who endeavored to climb the steep, high crags and investigate the summit was burned to death by the fires. Happily for the others, a wind arose which drove the ship southward, whence they saw the island now clear of smoke and spouting flames into the air, so that the whole mountain appeared to be aglow.