The Coast of Norway follows the edge of a mantle convection roll. This can be seen on this map:
The span from central Iceland to coastal Norway is 30°, the same as the span of a convection roll of the lower mantle. According to GPS measurements, Norway is drifting along this division line. This can be roughly explained with this drawing:
The wide black line along the coast of Norway shows the division line between the large convection rolls.
Question: Why are the convection rolls in the upper picture round, the lower has elongated rolls?
Answer: Because the upper one shows a slice along the latitude 64°N, whlie the lower indicates the vertical section compared with surface (convection rolls perpendicular to surface plane).
Magic Magma 