The POLAR Profile Transect Display attempts to integrate all the existing aeromagnetic, gravimetric, geological and geochemical investigations with the results of the deep seismic and electromagnetic studies carried out along the POLAR Profile. Our description is based on the stage of joint interpretation reached at the Second Earth Science Study Centre. The nearly 440-km long, NE-SW-trending POLAR Profile traverses Archaean and Early Proterozoic parts of the Baltic Shield. The thickness of the crust varies between 40 and 50 km and consists of three distinct crustal layers. A geological interpretation based on the various geophysical results is given for the uppermost 10-14 km thick layer. In the central part of the profile, the overthrust Early Proterozoic Lapland Granulite Belt forms a wedge-shaped body reaching the middle crust. The upper crust is underlain by a transparent layer 16-18 km thick with a smooth increase in velocity and density. A reflective lowermost 10-21-km thick layer has a high-velocity gradient. The crust-mantle has a pronounced topography.