Scotia Sea
Seafloor spreading in the West Scotia Sea continued until 6.6-5.9 Ma. The oldest volcanic activity in Central and Eastern Scotia Sea, i.e. the first signs of a volcanic arc, has been dated to 28.5 Ma. The South Sandwich Islands fore-arc originated in the Central Scotia Sea and was translated eastward by the back-arc spreading centre in the East Scotia Sea, i.e. the East Scotia Ridge. South Georgia's eastward migration ended about 9 Ma when the microcontinent collided with the Northeast Georgia Rise large igneous province on the South American Plate north-east of South Georgia. A submerged equivalent to the current South Sandwich Arc was relocated westward by the same spreading centre. After, and probably because of, the collision, the East Scotia Sea spreading centre split the ancestral South Sandwich Arc leaving a remnant arc under the Central Scotia Sea. The collision also produced the rugged Allardyce Range on South Georgia, making the -high range three times higher than the conjugate rocks on Navarino Island in Tierra del Fuego.