I. Den hvite granit i Sogn, geologisk optræden og tekniske egenskaper

Abstract

Forkortet: The white granite of Sogn in Western Norway, although for many years known and repeately called attention to be geologists, has only recently come into use as a building material to any extent. In this paper is given an account of the geology and the chief technical qualities of the granite. The small sketch map p.4 shows the granite areas in the district of Inner Sogn, and especially the great mass at Årdalsfjord. We can distinguish between two granites somewhat differing as to geological age and appearance, and also varying in mineralog- ical composition, due to a varying amount of mica (biotite). The less micaceous type is the younger type (Type I), and appears mainly at the borders of the great granite areas, and forms there a kind of eruptive breccia of great dimen- sions with numerous fragments from the surrounding rocks. Great continuous masses of the younger white granite thus occur only rarely but still they do occur in some places. The other type (Type II) with somewhat greater amount of mica, is the elder and appears in great continuous areas in several places. The eruption of the white granite of Sogn marks the conclusion of the great epoch of eruption in the central part of the Norwegian-Caledonian folding zone.