Iceland is located on the Mid-Atlantic Ridge. On the top of this ridge there is a rift, in between the Eurasian tectonic plate and the North-American tectonic plate. These two plates drift away from each other. In 1930 Sir Arthur Holmes made it clear that mantle currents make these movements possible. Step by step the mechanism of tectonic drift has been revealed, and my analysis represented here of the convection current system is a contribution to further clarifying the details of the inner structure of Earth.