Fig. 1. Lithospheric thickness, heat flow and inferred age of the lithosphere in northern Europe. In the western parts lithosphere thickness is based on seismic information, namely the long-range refraction profile FENNOLORA, which indicated low seismic velocity layers at depths of about 180–230 km along the Swedish eastern coast north of latitude 60 North. In southern Finland and the northernmost parts of the shield the thick lithosphere area was outlined from the interpretation of surface waves of earthquakes (Calcagnile, 1982). A similar variation of lithosphere thickness was presented by Babuska et al. (1988) but based on P-wave residuals of earthquake data. It should be noted that the original data by Calcagnile (1982) suggested no seismic asthenosphere under the thickest lithosphere area, and the present isolines are extrapolated from the original 170-km isoline of Calcagnile. The peripheral areas have a thinner lithosphere, about 100–170 km thick.