Messengers from the deep – the mantle under the North Atlantic area

Only the very outermost skin of the Earth will ever be directly accessible with the deepest boreholes extending to only about 10 km. This is negligible compared to the distance to the core of around 6000 km, or even the base of the crust, which is tens of kilometres thick under the continents. Nevertheless, we can gain information about the deep regions of the earth by two means: geophysics, and situations where deep rocks have become exposed at the surface.