Page:Encyclopædia Britannica, Ninth Edition, v. 17.djvu/634

 In various parts of the country we meet with extensive and highly-remarkable beds, geologically established with special local designations, and which, on the discovery of fossils indicating the sections, will, no doubt, at some later period be classed under the names given to the great and generally accepted formations with more precision than is possible at present. Such are, farthest north, the Gaisa series and the Raipas series in Finmark; in the Throndhjem region, the older of the Throndhjem schists, conglomerate and the sandstone series, and the Gula schists; in central Norway, environing the Jotun Fjelde, the alpine quartz. Of Mesozoic beds (Oxford clay) a few only still remain on the island of Andö in Vesteraalen; they consist of sandstone, coal, and oil-shale, with embedded Jurassic fossils.

The eruptive rocks—granite, syenite, porphyry, gabbro, norite, serpentine, greenstone, &c.—have broken through the beds of the various formations in a variety of ways, at one time as vast masses in continuous streams, at another time as isolated dome-like summits or simply cutting up wards as dykes. Old granite occurs in Christiansand stift, Thelemark, the Hardanger Waste, where it extends over extensive tracts and at its boundaries is seen to break through the Archaean formation, sending off multitudinous coarse-grained dykes, as also on the east side of the mouth of Christiania Fjord, in Aadal and in Hedal, south of Valders, and in Österdal. Very extensive tracts of granite are met with along the coast of Romsdal and in Nordre Throndhjem amt, where the coast, called Fosen, exhibits its characteristic rounded forms. Up through Nordland we pass numerous granite tracts of considerable extent. The whole of the Lofotens and Vesteraalen, together with all the outermost islets, holms, and skerries along the coast of Nordland, consist exclusively of granite. The interior of Finmark also has very large granite tracts. Extensive masses of post-Silurian granite and syenite, as also of porphyry in sheets, occur to the west and north of Christiania Fjord; it is at the borders of these masses that the Silurian system here becomes prominent. The largest tract of gabbro is that of the Jotun Fjelde; this rock is also met with extensively in Throndhjem stift and in Tromsö stift. Norite occurs chiefly near Sogne Fjord and at Egersund. Serpentine, in tracts of very considerable extent, is met with principally throughout Throndhjem stift. Dykes of post-Silurian porphyry, but more especially of greenstone, pierce in large numbers the Silurian system of eastern Norway; similar dykes, however, are also seen here and there throughout the country traversing both schist and granite.

Notwithstanding its great abundance of rocks, Norway cannot be said to be rich in valuable ores or minerals. Thus, for example, true coal does not occur; Jurassic has been found on Andöen, but only in seams extremely limited in extent. Gold is met with very sparingly in veins of quartz at Eidsvold, in the rivers of Finmark, and along with silver in the Kongsberg mines. The latter metal is found as native silver in veins of calcareous spar at Kongsberg, where the state owns a silver mine of considerable value. Copper occurs in numerous localities, as Thelemark, Röros in the Throndhjem district, many parts of the west coast, more especially at Vigsnæs on Karmöen, and in northern Norway at Kaafjord in Alten. Nickel is produced in some parts from sulphuretted iron ore, particularly on the island of Senjen in Tromsö amt. Iron ores are met with in southern Norway, particularly along the coast near Arendal. According to the geological survey, the presence of ore is intimately connected with the eruptive rocks, at the limits of which they are accordingly to be looked for, both in the Archæan and in the later formations; thus on the confines of the oldest granite we find alike iron and

copper ore; on those of gabbro, sulphuretted iron ore containing nickel and apatite.

Volcanoes, in a strict sense, and their subsequent results, such as hot springs, have not been met with in Norway.