The Scotia arc is the eastward-closing loop of mountains and locally emergent submarine ridges extending from the southernmost Andes through the active South Sandwich volcanic arc to the Antarctic Peninsula. Its origins lie in the Jurassic initial fragmentation of Gondwana. This fragmentation involved extreme intercratonic extension, Pacificward translation of rotating crustal blocks, and an ignimbrite flare-up. Relative motion between South America, Africa, and East Antarctica during the opening of the southern ocean basins resulted in mid-Cretaceous uplift of the Pacific margin cordillera and translation of elevated crustal blocks eastward to form the North and South Scotia Ridges. The South Sandwich volcanic arc system originated in Neogene westward-directed subduction beneath oceanic crust formed between South America and Antarctica and serves as an excellent tectonic laboratory. The physiography of the entire Scotia arc region has profoundly influenced the onset and development of the Antarctic Circumpolar Current and migration of marine and terrestrial biota.