Southernmost continent on Earth, primarily of ice and snow. Antarctica is the location where the second, and far more ancient Stargate was found. When Jack O'Neill and Samantha Carter emerged through the beta gate, they believed they had been transported to an ice planet.
After discovering the Stargate to have, indeed, sent them back to Earth, a research team was set up to determine the impact of this information against current knowledge of the Ancients and the gate network. This team only found the remains of two Jaffa, and for roughly five years were relatively unsuccessful in discovering anything that related to the theories which had been formulated.
Very nearly ready to pack up and return to the United States, the research team discovered the preserved body of what was later to be recognized as a frozen being of the first Ancient race, or so it was believed.
Antarctica was the location of the final battle of Earth's forces against Anubis. This confrontation left the most powerful Goa'uld force in the galaxy defeated.
Solitudes - O'Neill and Carter emerge through a Stargate which, they later discover, has been buried in Antarctica for potentially thousands of years.
Frozen - SG-1 is called back to Antarctica when a frozen human is discovered in the ice.
Lost City, Part 2 - SG-1 returns to Earth from Proclarush with evidence that the lost city of the Ancients is buried in Antarctica.
Rising, Part 1 - Dr. Weir leads an expedition at Atlantus Outpost in Antarctica when Dr. Jackson finds a vital piece of evidence explaining the present origins of Atlantis.