Before we thought about the plates of N-America and Europe as splitting apart. Now we know more, namely that they rotate in opposite directions. Finding it out is not enough, though. We have to learn it.
Also note the two vectors from Iceland. The vectors found in NW and NE of the country are symmetric around NS-axis (same deviation from North). It shows the role of the main mantle division line drawn on the basic map. These vectors are parallel to the rotation found farther to the south on the two continents.
The speed of the tectonic drift in Iceland is close to 2.5 cm a year, oriented towards NE and NW. It is faster than previously thought, when only the division rate of a little less than 1 cm a year for each plate was measured.