Plate data: Bird (2003), PB2002, converted by Hugo Ahlenius, Nordpil (ODC-By 1.0). Land: Natural Earth (India POV).
The Antarctic Plate carries the continent of Antarctica and the Southern Ocean floor around it. USGS lists it with the Pacific Plate among the largest plates on Earth. Its edge is mostly spreading ridges and the transform faults that offset them. Convergent boundaries make up only a small share, as the table below shows.1
Antarctica was not always frozen. USGS points to fossils of tropical plants, found as coal deposits in Antarctica, as evidence that this land once sat closer to the equator. Signs of dramatic climate change like this were part of what Alfred Wegener set out to explain with his theory of continental drift.
Dinosaurs tell the same story. In 1991 paleontologists found Cryolophosaurus ellioti, the only dinosaur species found on the continent of Antarctica, at Mount Kirkpatrick, only 600 km from the present-day South Pole. It lived about 200 million years ago, when Antarctica was still part of Gondwana and had a climate mild enough to support large plant-eating animals. With the break-up of Gondwana, Australia drifted north toward the equator and Antarctica drifted south to the South Pole (USGS).
Its neighbors have changed in recent geologic time too. Bird (2003) explains that the former Phoenix plate, which spread at the Drake Rise and sank at the South Shetland Trench, has now merged with the Antarctic Plate. Off South America, the Juan Fernandez Plate, a small oceanic plate about 410 by 270 km, sits in a fork of the East Pacific Rise between the Pacific, Nazca and Antarctic Plates. Bird draws the Antarctic Plate in contact with the small Shetland, Scotia and Sandwich Plates south of South America as well (Bird 2003).
Antarctic Plate in numbers
Measured from its PB2002 outline, the Antarctic Plate covers about 58.2 million km², or 11.4% of the
Earth's surface. That makes it number 3 by area of the 52 plates in the model.
It reaches every line of longitude and spans from 90°S to 26°S.
Its edge is about 40,298 km long, mostly divergent:
51.4%divergentDivergent boundary. Plates pull away from each other and new crust forms between them. Source (20,731 km)
, 7.1%convergentConvergent boundary. Plates move toward each other and crust is destroyed as one plate dives under another. Source (2,871 km)
and 41.4%transformTransform boundary. Plates slide horizontally past each other. Crust is neither made nor destroyed. Source (16,696 km)
.
Countries whose main landmass sits on this plate: Antarctica and Fr. S. Antarctic Lands. Countries that straddle a boundary
are listed under the plate that holds the center of their largest landmass.
Along its boundaries it moves a mean 4.6 cm/yr relative to its neighbors, fastest against the Pacific Plate. Bird (2003)
Neighboring plates Neighbors. Plates that share a boundary with this plate. Most plate movement happens along these narrow zones between plates. Source
The Antarctic Plate shares a boundary with 10 plates in PB2002, longest shared edge first.
The longest, about 11,155 km, is with the Australian Plate; the shortest, about 93 km, is with the Sandwich Plate.
Computed from the PB2002 plate outlines and boundary types (Bird 2003).
Antarctic Plate FAQ
How big is the Antarctic Plate?
About 58.2 million km², or 11.4% of the Earth's surface, measured from its PB2002 outline. It ranks 3 of 52 plates by area.
Which plates border the Antarctic Plate?
10 plates: Australian Plate, Pacific Plate, Somali Plate, Nazca Plate, African Plate, Scotia Plate, South American Plate, Shetland Plate, Juan Fernandez Plate and Sandwich Plate.
What kind of plate boundaries does the Antarctic Plate have?
Mostly divergent boundaries. 51.4% divergent, 7.1% convergent, 41.4% transform, of 40,298 km in total.
How fast does the Antarctic Plate move?
Relative to its neighbors, a mean 46.4 mm/yr (4.6 cm/yr) along its boundaries in PB2002. The fastest boundary is with the Pacific Plate.
