A sub-Antarctic treasure

Despite several transits of the waters between Antarctica and Australia over preceding decades, Macquarie Island remained undiscovered until 1810. In January of that year, Frederick Hasselborough of the brig Perseverance discovered an island overflowing with millions of penguins and — most importantly for him — around 250,000 seals.

Teeming animal life is the most obvious feature of Macquarie Island, which was named after the governor based in Perseverance’s home port, Sydney. But had Hasselborough and those who followed him not been so blinkered by profits from the oil of slaughtered seals, they might have seen some other remarkable qualities of this tiny island.

The location of Macquarie Island has given it some very special qualities. From Tasmania or New Zealand, the island lies about half way to Antarctica at 54°38'S latitude and 158°52'E longitude. It is perched atop the mainly-submarine Macquarie Ridge, at the junction of two tectonic plates, the Pacific and the Indo-Australian, which has made it a focus of major earthquakes.

The colliding tectonic plates and the ocean above combined to create a landform like no other. Alone among the sub-Antarctic islands, Macquarie is composed entirely of oceanic crust and rocks from Earth’s mantle, deep below the ocean floor. Its rocks, including fine examples of pillow basalts, have been shaped over millions of years by wave action and other marine processes. The uniqueness of the exposed landform resulted in World Heritage listing in 1997.