The Gardar period in southern Greenland

Between Narssaq and the Inland Ice in southern Greenland, faulted outliers of sandstone and volcanic rocks lie unconformably upon a pre-1600 m.y. 'basement' of metamorphic rocks, migmatites and granites. Both 'basement' and the supracrustal rock outliers are intruded by a variety of dykes and central complexes. The region, which is the most pop ulated in Greenland, has received a steady flow of visitors from Europe since the beginning of the 19th century. One of the first notable geologists to visit the area was Giesecke whose record of several years of travel and investigation still finds a useful place in the geological literature (Giesecke, 1910). He was followed later in the 19th century by Steenstrup, Flink, Ussing and others, all of whom paid particular attention to these younger igneous rocks, especially to the nepheline syenites of Ilimaussaq and the Igaliko region, on account of their exotic rock types and their content of hitherto unknown minerals; this was also true of the I vigtut cryolite deposit which was mined from 1855 until recently.