Prince Edward Islands - Geography and Geology

Geography and Geology

The island group is about 955 nmi (1,769 km; 1,099 mi) south-east of Port Elizabeth in mainland South Africa. Marion Island (46°54′45″S 37°44′37″E / 46.9125°S 37.74361°E / -46.9125; 37.74361 (Marion Island)), the larger of the two, is 25.03 km (15.55 mi) long and 16.65 km (10.35 mi) wide with an area of 290 km2 (112 sq mi) and a coastline of some 72 km (45 mi), most of which is high cliffs. The highest point on Marion Island is Mascarin Peak (formerly State President Swart Peak), reaching 1,242 m (4,075 ft) above sea level. Boot Rock is about 150 metres (492 ft) off the northern coast.

Prince Edward Island (46°38′39″S 37°56′36″E / 46.64417°S 37.94333°E / -46.64417; 37.94333 (Prince Edward Island)) is much smaller—only about 45 km2 (17 sq mi), 10.23 km (6.36 mi) long and 6.57 km (4.08 mi) wide—and lies some 12 nmi (22.2 km; 13.8 mi) to the north-east of Marion Island. At the Van Zinderen Bakker Peak north-west of the center, it reaches a height of 672 metres (2,205 ft). There are a few offshore rocks along the northern coast, like Ship Rock (100 m/328 ft, north of northernmost point) and Ross Rocks (500 m/1,640 ft, from the shore).

Both islands are of volcanic origin. Marion Island is one of the peaks of a large underwater shield volcano that rises some 5,000 metres (16,404 ft) from the sea floor to the top of Mascarin Peak. The volcano is active, with eruptions having occurred between 1980 and 2004.