The 8 x 10 km Ile aux Cochons, at the W end of the Crozet Islands, is a single stratovolcano with a small summit caldera and more than 60 scoria cones. The production of phreatomagmatic breccias interbedded with thin lava flows was followed by block faulting and the eruption of scoria cones and lava flows along four radial fracture systems. Bellair (1964) considered the Morne Rouge cone on the E coast to be younger than a cone on Possession Island estimated to be several hundred years old.