The Jan Mayen Ridge is a sliver of continental crust – a microcontinent – bounded by rifted continental margins on both sides.  The eastern margin developed as the outermost part of the continental shelf of Greenland during the initial breakup of the continent and the opening of the Norway Basin. It is characterized by  an eastward thickening  pile Mynd_21_2011-02-18_Cross-section_Legend_AnBof basaltic lava flows which was erupted over the preexisting continent during the events leading to the creation of the ocean basin east of the ridge (Norway Basin). The western margin developed as a result of rifting within the Greenland continental shelf and seafloor spreading on the Iceland  Plateau. It is characterized by tilted extensional fault blocks and an extensive complex of sills or lava flows which covers the deep basins west of the ridge.