Iceland Geology

Geology. – Iceland essentially consists of a plateau made up of recent volcanic rocks. Fjords and valleys form marginal depressions while in the interior high plateaus about 400-800 rn prevail. sm Above these plateaus there are isolated mountains and great mountain massifs which give rise to expansions of ice; and from the inside some ridges up to 800-1200 m high. they push into peninsulas and promontories. The core of the mountains is made up almost exclusively of Tertiary and Quaternary volcanic rocks. Other types of rocks, such as sandstone and limestone, appear only rarely. The main mass of the mountains, both in the interior of the island and on the southern coasts, is mainly made up of tuff, especially palagonite tuff. Basalt is found on the western coasts, In the north and east, liparite, on the other hand, is very rare. The spato of Iceland is found in one place and precisely on Mount Grákollur near Helgastadhir in the eastern part of the island. Most of the sand and gravel that covers the valley bottoms, the basins and the plains comes from these rocks. A large part of the surface of Iceland is occupied by marshy land. Magnetic iron is found in large quantities in basalt, tuff and lava; sometimes in such large masses that the magnetic needle is affected by them. In some places, such as on Mount Esja near Reykiavík, there is also copper, and around this city even gold. Wide plains are covered by eruptive formations of the current geological period and above all by lava (in tuff and lava; sometimes in such large masses that the magnetic needle is affected by them. In some places, such as on Mount Esja near Reykiavík, there is also copper, and around this city even gold. Wide plains are covered by eruptive formations of the current geological period and above all by lava (in tuff and lava; sometimes in such large masses that the magnetic needle is affected by them. In some places, such as on Mount Esja near Reykiavík, there is also copper, and around this city even gold. Wide plains are covered by eruptive formations of the current geological period and above all by lava (hraun), pumice (vikur) and, more rarely, obsidian (hrafntinna) and sulfur (brennisteinn). The oldest formations, however, had the greatest influence on the configuration of the country.

Exploration. – The identification of Pytheas’ Thule with Iceland is still highly debated and therefore we cannot assert that the island was already known in classical antiquity. It appears more likely that the Irish monks, than according to Dicuil (De Mensura orbis Terrae) in the first half of the century. VIII would have retired to live as anchorites in the extreme northern island, we have followed the most ancient and uncertain raids of Norman pirates. The first definitely ascertained expedition dates back to 867, that of Nadodd who, while sailing between Norway and the Faroe Islands, was pushed as far as Iceland; after that the island became a popular destination for Norman travelers and indeed a considerable emigration began at that time, caused by the political changes that occurred in Norway at the end of the century. IX. These Normans, together with some Irish led by Aud, widow of Olaf the White, king of Dublin, colonized the coasts of the island and occupied all the land on the east, south and west coasts, susceptible to cultivation.

The methodical and scientifically based study of the territory was begun in the century. XVIII by the Scientific Society of Copenhagen, which in 1752 sent a mission formed by Eggert Olafsen and Bjarne Povelsen with the task of studying the geography and geology of the island. The exploration lasted from 1752 to 1757 and the results were disclosed in an extensive report published in Danish in 1762 and then translated into German in 1774 (Olafsen und Povelsen. Reise durch Island). A few years later a new study, with rather economic objectives, was carried out on behalf of the Danish government by Olaus Olavius ​​(1775-77), who wrote an interesting report also translated into German (Oekonomische Reise durch Island, Dresden 1783); the volume was accompanied by a beautiful map which is the first good representation of Iceland. These two publications were for a long time the only comprehensive treatises and formed the basis of the geographical knowledge of the island, to which many later publications added observations and particular studies, among which the excellent letters of Uno von Troïl (Letters on Iceland, London) deserve to be mentioned. 1780), who visited the island in 1772 in the company of the English naturalist Joseph Banks, as well as the report by Henderson who resided in Iceland in the years 1814-15 and the letters from Xavier Marmier who visited the island in 1835-36. Among the later scholars we mention WS Walthershausen, who wrote a Physikalische geographische Skizze (Göttingen 1847); to Ch. S. Forbes, who illustrated its volcanoes, geysers and glaciers; to the Germans W. Preyer and F. Zirkel, who explored the island in 1860, and to the Englishman WC Lock who inserted various notes on Icelandic volcanoes in the Proceedings of the English geographical R. Soc. The first scientific map was drawn at the scale of 1: 480,000 (Copenhagen 1844).

In recent times, physical geography has made numerous advances mainly through the work of the Icelandic Th. Thoroddsen. Among his most important campaigns we remember that of 1884 in the internal plateau of Ódádahraun, that is, in the great lava desert dominated by the volcanic cones of Askja (m. 1412) and Trölla dyngja (m. 1491); that of 1886 in which he explored the great north-western peninsula up to the North Cape, also studying the glaciers of this section. He later made other trips to Vatna jökull, the largest glacier on the island, and later devoted himself to the study of the geological and topographical conditions of the little-known north-east region where he detected numerous volcanic phenomena. Geografisk Tidskrifl of Copenhagen) and in various volumes, and constitute the best scientific material around the region. Fundamental to exploration is his Geschichte der islandischen Geographie (Leipzig 1898, vol. 2).

Coasts. – The southern coast, from Cape Eystrahorn to the SE. up to the mouth of the Ölfusá, it forms a very regular arched line, with few headlands and inlets; on the other hand, near the mouths of rivers, coastal lakes (lón in Icelandic), separated from the open sea by narrow strips of land. On the west coast, however, the fjords are very numerous. The two large gulfs Faxa fjördur and Breidhi fjördhur are interposed between the three peninsulas of Reykjanes, Snaefellsnes and the triangular north-west peninsula, connected to the rest of the island only by a narrow strip of land. The last of the peninsulas, especially in its NO part. between C. Biargtangar and C. Horn, it is engraved by numerous fjords; the largest of these are the Isa fjardhar and the Jökul fjördhur. On the northern coasts there are also the deep fjords Húna flói, Skaga and Eyia and the more open ones of Skiálfandi, Axar and Thistil fjördhur. Between the latter two is the small peninsula Melrakkasljetta, with Cape Rifstángi, the most northerly in all of Iceland. On the east coast, the fjords are smaller. The coasts of Iceland, except the southern ones, which for the most part are low and sandy, are generally steep, with a series of high promontories and with sloping rock faces like terraces (hamrar). A number of islets accompany the coasts; the most important of these are the Vestmannaeyjar, facing the southern coasts.