The Reykjanes Ridge and Kolbeinsey Ridge form a rather regular division line between tectonic plates, south and north of Iceland. In between the pattern is more complex. As for the convection rolls below, they are in a way more complex under Iceland, due to the transit zone of polar and equatorial convection rolls.
The two systems meet at 64°N, and both are subject to the same mathematical formula. If we trace the Reykjanes Ridge Convection Rolls, we find this picture: