Research boreholes confirmed dykes in excess of 50% of the structure at the depth of 3 km. In eastern Iceland there are ruins of at least 14 central volcanoes, some of which are very obvious on the surface.
The Ice Age glaciers carved 1-3 km off the surface and brought magma reservoirs, magma chambers and intrusions to the surface and left them there when they retreated. The earth’s crust is flexible and started rising when the great weight of the ice gradually disappeared. The fact that the great icecap Vatnajokull is growing smaller might explain the increased shallows of River Hornafjardarfljot estuaries.