The most frequent eruptions have been from Hecla, which numbered 43 periods, of activity up to 1845; they were generally violent. The outflow of 1783 wasted a large extent of country, while that of 1845 continued at inter vals for nearly a year, pouring out a lava stream 50 feet deep and a mile wide.
Hecla has the record for devastation, its single eruption (1783) causing almost incon ceivable havoc. It is asserted that no less than 230,000 head of stock were killed, including more than half of the cattle, three-fourths of the horses and four-fifths of the sheep. These frightful losses of fields and of stock caused famine to fall on the land, and in succeeding years 9,500 persons died of starvation, one fifth of the entire population.
Earthquakes are naturally associated with volcanic energy, though not directly connected with it. The earthquake of 1784 destroyed 92 homesteads and injured 372 others. The dam age of that of 1896 was fully as great, half of the 320 homesteads affected being destroyed. The lava beds work the greatest injury, as they gradually diminish the arable and pasturel areas of the island. The greatest lava producers have been Askja, Hecla and Katla; these parent volcanoes are encircled by lava sheets which aggregate in area nearly 5,000 square miles. The Odadahrum field, to the north of Vatna, is an unbroken sheet of 1,700 square miles, in cluding branches. One danger is the melting of the surrounding neves by the burning lava, thus producing devastating inundations. The most destructive of such floods was caused by the eruption of Oearef a Tokeell (1362), when 40 farms with occupants and stock were swept bodily into the ocean.
Glaciers and Neva.— There are 200 or more of neves, or permanent snow-fields, the most extensive, 2,300 square miles being that of Vatna, which borders the Atlantic. While the northern snow-line of Vatna, facing the Arctic Ocean, is at an elevation of 4,000 feet or more, the southerly snow-bearing winds of the North Atlantic are so effective that they bring the neve of the oceanic slopes down to 2,000 feet. From this neve issues a glacier of nearly 200 square miles area. Practically all
the glaciers are dead, that is do not reach the sea, though the Breidenmerkur closely ap proaches the Atlantic. On the Arctic and coldest coast, the lowest glacier terminal is 2,500 feet above the ocean.
Geysers.— Hot springs exist in large num bers, and are of three types: quiescent springs, boiling mud lakes, and geysers where boiling water is ejected interrnittingly. The largest geyser system — numbering a hundred — is about 60 miles northwest of Hecla, and 70 miles from Reikjavik. The best known are the Great and Little Geysers, and Storkr (the churn). The Great Geyser is surrounded by a silicate basin, 70 feet across and 5 feet deep. The vent extends 80 feet downward, and its diameter is about 8 feet. At irregular intervals, varying from 6 to 30 hours, the Great Geyser ejects with a roar a column of boiling water to great heights —80 to 150 feet. The surface water usually has a temperature near but occa sionally reaches Agriculture, Fisheries and Industries.— About 50,000 persons are engaged in agri culture, of whom a surprisingly large number i are owners. Hay is the principal crop, fol lowed by potatoes and turnips. Berries are the only native fruits. Stock-raising is the import ant factor. In 1914 there were 1,021 goats, 25,380 cattle, 46,644 horses and 585,022 sheep. Grain cannot be profitably grown, thus necessi tating importation of cereals. The most import ant of the exports are the products of the deep-sea fisheries, in which 15,890 persons were engaged in 1914. Cod is the most lucrative, fol lowed by herring and salmon. Industries are limited, only 7 per cent being employed therein. The principal industries are the curing and salting of fish, rendering of oil, preparation of eiderdown and the manufacture —largely domestic —of woolen cloth for local use.
Minerals.— Difficulties of transportation and poverty of metallic deposits have delayed the exploitation of the minerals of Iceland. In recent years a mine of the well-known Iceland has been developed, and with the growing demand for fuel the mining of the low-grade coal is also being attempted.