5. Hekla, in September 2, 1845 (-46), broke out the twenty-sixth time, according to popular writers, throwing up ashes, which fell in the Orkneys, and which gave the first intelligence of the event.
6. Kötlu-gjá again was slightly active, vomiting ashes and water in May 1860, its thirteenth eruption.
7. It has been generally assumed that on March 23, 1861, the Öræfajökull broke its long rest, and the smoke is said to have tarnished silver at the distance of fifty miles. But Mr Jón A. Hjaltalín, who was in Iceland during that year, denies having heard of any convulsion, nor was it mentioned by the island papers. He adds, “What is spoken of in Metcalfe’s book was a ‘Jökul-hlaup.’”
An ash-eruption from Trölladýngjur is recorded in 1862, but accounts of it greatly vary. Mr Keith Johnston chronicles nine eruptions extending through nearly five centuries and a half—namely, the submarine volcano in the middle of Breiði Fjörð (A.D. 1345), Trölladýngjur (1510), Herðubreið (1716-17), “Krabla” (1724-25), Leirhnúkr (1730), Síðu Jökull (1753), Öræfajökull (1755), Hnappafellsjökull (1772), and Skaptárjökull (1783). And he further informs us that two great groups are active—Leirhnúkr, “Krabla,” Trölladýngjur, and Herðubreið,[71]—all nearly on a parallel of latitude to the north-east; and Hekla, Aust Jökull, Mýrdals, and Öræfa, placed in a right-angled triangle to the south.
Concerning the unvisited volcano in the snows of the Vatnajökull, all procurable details will be found in the Journal. The author was surprised to find that not one of the known centres was in a state of activity, although every preconceived idea suggested that the summer of 1872 would be one of unusual perturbation.[72] Two days before the outbreak of Vesuvius (January 1, 1872), shocks began in the north-east of Iceland. On the afternoons of 16th and 17th April, Húsavík, a small comptoir to the east of Skjálfandi Fljót, suffered severely, as will appear in a future page. This immediately followed the fearful cyclone at Zanzibar (April 15), a phenomenon unknown in former times, which destroyed part of the town, and which sank most of the foreign and native craft,[73] doing damage estimated at £2,000,000. The earthquake at Húsavík also took place only thirteen days after the earthquake at Antioch (morning of April 3), which shook down two-thirds of the houses, and killed nearly one-third of the people. Moreover, shocks were reported at Accra on the Gold Coast, a town which had been almost destroyed some ten years before.[74] Followed (May 1) by the cyclone at Madras, which breached the pier, severely injured the city and suburbs, and wrecked eleven merchantmen, drowning many of the crew. Lastly came the report that the unseen crater in the untrodden snows of the Vatnajökull, whose smoke was first seen in August 1867, had again begun to “vomit flames.”
Meanwhile the eruptions of Vesuvius continued till April 26, when a new crater built a hill in the Atrio del Cavallo, where only a fissure before appeared. Professor Palmieri, who stuck staunchly and gallantly to his observatory on the banks of the new Styx, reported that the mountain was sweating fire at every pore, and that after the showers of ashes and red-hot stones, and the discharges of lava and “boiling smoke,” storms not less dangerous had begun to rage. These meteors, as a rule, occasion great floods, which, sweeping down the ashes and rapilli that cover the slopes, complete the ruins of the lands spared by the lava. During this eruption, a report was spread that the crater of Vesuvius had become an electric pile; that strong currents, generated by the violent ejections of the crater, showed themselves in lightnings, flashing with a dry and hissing sound from the great trunk of smoke and ashes; and, finally, that an earthquake might at any moment shake Naples to its foundation. This abnormal electricity may explain the meteorological peculiarities of the spring of 1872, even in England, where May behaved itself with the leonine violence of March. The great Pacific earthquake (August 1867) and the tremendous and unusual storm which simultaneously visited the eastern coast of South America, to quote no other instances, showed that, whilst similar effects usually are of limited extent upon solid ground, they stretch to great distances at sea, and they may influence the atmosphere in the furthest regions of the world. Though we may accept only as provisional the geological theory which places volcanoes upon fissures or solutions of continuity in the earth’s surface,[75] we must remember that on October 17, 1755, a fortnight before the earthquake which shook down Lisbon, the Kötlu-gjá fissure began the terrible eruptions that lasted for a year: at the same time the waters of Loch Ness were agitated; the British Isles were rocked by repeated oscillations, and shocks extended to Asia and to America. Again, in 1783, the Upper Calabrian earthquake (February 5 and 7, and March 28) was closely followed by the fearful phenomena of the Skaptárjökull.[76] Thus Nature appeared to have made in the summer of 1872 every possible arrangement for a grand pyrotechnic display; yet the author can positively assert that during the whole of his stay in Iceland not one of the twenty-seven to thirty great vents showed a symptom of activity. Indeed, only one was ever reported to be in existence, and that one has never been visited.
Professor Bunsen has shown that active volcanoes whose temperature is high, discharge sulphurous acid, whilst the dormant give forth sulphuretted hydrogen; hence the irregular and simultaneous appearance of these two gases which play a most important part in Iceland. “Let a piece of one of the igneous rocks be heated to redness, and permit the vapour of sulphur to pass over it. The oxide of iron is decomposed; a portion of sulphur unites with the iron which remains as sulphuret; the liberated oxygen unites with the remaining sulphur, and forms sulphurous acid. Let the temperature of the heated mass sink just below a red heat, and then let the vapour of water be passed over it: a decomposition of the sulphuret before formed is the consequence; the iron is reoxydised, and the liberated sulphur unites with the free hydrogen to form sulphuretted hydrogen. Thus the presence of two of the most important agents in volcanic phenomena is accounted for. These are experimental facts capable of being repeated in the laboratory, and the chronological order of the gases thus produced is exactly the same as that observed in nature.”
The most remarkable features of the island, after the volcanic, are the Fjörðs,[77] or firths proper, conducting streams and admitting the sea; opposed to Víks and Vágrs, bights and bays, mere indentations of the coast. Though of igneous origin, they are compared with the granitic features of Norway, where a volcano is unknown, and yet where the shape becomes that of an arête, a fish’s dorsal bone with regular ribs on both sides: this flat snow-capped ridge is “the keel” of the maritime population. The popular theory (Students’ Manual of Geology, Jukes and Geikie, Blacks, Edin. 1872) is that the Fjörðs are glens once submerged, raised above water, and hollowed out by glaciers and by the various influences which come under the name of “weather.” Glacial action is, we must own, distinctly traced in most parts of the island. But in many places, Berufjörð for instance, there is no room at the head of the dwarf amphitheatre for a glacier of any magnitude. As in the Færoe archipelago, these ravines are the rents and fissures which divided and fractured the first upheaval; and in Iceland they were bound together by the action of earthquakes and eruptions, ice and snow, wind and rain. The greater gorges are found chiefly on three sides of the island. The south-western shore, like that of Ireland, is digitated by gales, currents, and Greenland ice, and it abounds in “Út-ver,”[78] the narrow-necked peninsulas of Norway. The Síða, or sea-“side” to the south-east, is a long, narrow strip of habitable land between the mountains and the waters: here the Fjörðs were obliterated by the combined action of the Jökulls. Under the name “Fjörðs” are also included immense bays, as the Faxa Fjörð, sixty-five miles across; the Breiði Fjörð, forty-five miles wide; and the Húnaflói, into which the Arctic Sea sends its unbroken swell, running forty-six miles deep and twenty-seven in diameter. The western features are, as a rule, broad, with shallow sag: here, according to some,[79] was deposited the Surtarbrand[80] or lignite, and, like the driftwood of Kerguelen Island, it escaped incineration by subsequent eruptions from causes analogous to the operation of charcoal burning. The northern firths are long and deeply indented, and the eastern are sharp and narrow, encased in walls of Palagonite, trap, and basalt.
The archipelagoes and solitary islands outlying Iceland are invariably small; and in places, as will be seen, the “stacks” and “drongs” form a “skerry-guard,” almost a false coast.
Concerning a common feature of the interior, the Gjá (pron. Geeow, or like ow in fowl), rent, chasm, or fissure, details will be given in the course of the Journal. Here it may be mentioned that it perfectly resembles the “Ka’ah” of the Lejá and the Haurán, and the Lava Fields in the Far West of North America, which lately sheltered the “Indians,” and gave so much trouble to the Federal troops.