Age of Atlantic islands, as indicated by the oldest rocks found on them apparently tends to ncrease with increasing distance from the Mid-Atlantic Ridge. The numbers associated with the islands give these ages in millions of years. Geologists divide Iceland into three areas of different ages, the central one being the youngest. Islands that have active volcanoes are represented by black triangles: most of these lie on or near the Mid-Atlanric Ridge (J.T. Wilson, 1963, Sci. Amer.)