Dahll, Tellef & Kjerulf, Theodor

Tellef Dahll (1825-1893) & Theodor Kjerulf (1825-1888) were Norwegian geologists and mineralogists. From 1858 Dahll & Kjerulf together led the first geological survey of Norway; the resulting maps were published as Geologisk Kart over det Sondenfjeldske Norge (in two separate maps), Trondheim stift and Det nordlige Norge. Kjerulf's contributions to Norwegian geology were particularly significant. From 1858 to 1888, he served as the first director of the Norwegian Geological Survey (Norges geologiske undersøkelse), which he had been instrumental in establishing. He also contributed to the systematic and detailed mapping of Norway's bedrock. Dahll worked mostly for private mining companies, in which capacity he found valuable mineral resources including coal and iron ore; his discovery of gold launched the 1870 gold rush in Finnish Lapland. He discovered a previously unknown element which he named Norwegium, and the phosphate mineral dahllite (hydroxylapatite) is named after Tellef Dahll and his brother Johann, also a mineralogist.