Before the formation of the plate began 40 million years ago (40Ma), these fragments formed a continuous landmass from Patagonia to the Antarctic Peninsula along an active subduction margin.
The northern ridge stretches from Isla de los Estados off Tierra del Fuego in the west to the microcontinent South Georgia in the east, with a series of shallow banks in between: Burdwood, Davis, Barker, and Shag Rocks.
Surface expressions of the plate boundary are found north of the islands suggesting a long-term presence of the transform fault there.
[10] The South Georgia microcontinent was originally connected to the Roca Verdes back-arc basin (southernmost Tierra del Fuego) until the Eocene.
[7] At the eastern tip of the Antarctic Peninsula, the beginning of South Scotia Ridge, a small and heavily dissected bank degenerates into several outcrops dominated by Paleozoic and Cretaceous rocks.
This volcanic active island arc has submerged ancestors in Jane and Discovery banks in the southern ridge.
Heading south along the ridge, the subduction rate decreases until its remaining oblique motion evolves into the Shackleton fracture zone transform boundary.
The south-western edge of the plate is bounded by the Shetland microplate separating the Shackleton fracture zone and the South Scotia Ridge.
[17] The timing of the formation of the Scotia plate and opening of the Drake Passage have long been the subject of much debate due to the important implications for changes in ocean currents and shifts in paleoclimate.
The thermal isolation of Antarctica, engendering the formation of the Antarctic ice sheet, has largely been attributed to the opening of the Drake Passage.
[4] The earliest marine fossils found on the Maurice Ewing Bank, on the eastern end of the Falkland Plateau, are associated with the Indian and Tethys Oceans and probably slightly more than 150 Ma.
The Weddell Sea opened and spread along the southern margin of the Falkland Plateau and into the Rocas Verdes back-arc basin which extends from South Georgia and along the Patagonian Andes.
[20] The acceleration of the westward motion of South America and the inversion of the Rocas Verde Basin finally lead to the initiation of the Scotia Arc.
[21] Between the Late Cretaceous and the Early Oligocene (90–30 Ma) little changed in the region, except for the subduction of the Phoenix plate along the Shackleton fracture zone.
The ongoing lengthening of the North Scotia Ridge beyond the Burdwood Bank caused South Georgia to move further east.
The banks of the North Scotia Ridge contain volcanic rocks similar to those found in Tierra del Fuego, including on Isla de los Estados on the easternmost tip.