The evidence for the presence of a major tectonic lens, the Steinkjer Mega-boudin, in the Caledonian allochthon of northern Trøndelag is summarized. The lens itself is composed of three distinct tectonic units: an upper complex of schists, gneisses and amphibolites, a middle unit of dolerite-intruded feldspathic sandstones, and a lower unit of feldspathic sandstones lacking dolerites. Lamprophyres occur locally in the lower unit. These three units are directly comparable with the Seve, Särv, and Offerdal Nappes of the Swedish Caledonides.
Some remarks on the Steinkjer Mega-boudin