After breakup from Gondwana (the southern part of the supercontinent Pangea), the Antarctic plate began moving the continent of Antarctica south to its present isolated location, causing the continent to develop a much colder climate.

[4] The Antarctic plate started to subduct beneath South America 14 million years ago in the Miocene epoch.

At first it subducted only in the southernmost tip of Patagonia, meaning that the Chile triple junction lay near the Strait of Magellan.

As the southern part of the Nazca plate and the Chile Rise became consumed by subduction the more northerly regions of the Antarctic plate began to subduct beneath Patagonia so that the Chile triple junction lies at present in front of Taitao Peninsula at 46°15' S.[5][6] The subduction of the Antarctic plate beneath South America is held to have uplifted Patagonia as it reduced the previously vigorous down-dragging flow in the Earth's mantle caused by the subduction of the Nazca plate beneath Patagonia.

The dynamic topography caused by this uplift raised Quaternary-aged marine terraces and beaches across the Atlantic coast of Patagonia.