Macquarie Island

Macquarie Island is a subantarctic island located in the south-western Pacific Ocean.

It sits roughly halfway between New Zealand and the Antarctic continent. The island is a part of the Australian state of Tasmania. It has been governed by Tasmania since 1880. In 1978, it became a Tasmanian State Reserve. Later, in 1997, it was named a UNESCO World Heritage Site. This title was given because the island is a site of major geoconservation significance. It is a very important place for understanding the Earth's crust.

The island's unique shape and structure are quite distinct. It consists of two high plateaus at the north and south ends. A low and narrow strip of land called an isthmus joins these two plateaus.

The highest points are Mount Elder on the northeast coastal ridge. In the south, you will find Mounts Hamilton and Mount Fletcher. These peaks reach heights of 540 meters and 512 meters respectively. The island is almost equidistant between Tasmania and the Anderson Peninsula in Antarctica. It is also located southwest of Auckland Island and north of the Balleny Islands.

Geologically, Macquarie Island is an extraordinary place. It is an exposed portion of the Macquarie Ridge. This ridge is a long fault zone in the oceanic crust. The island sits exactly where the Australian plate meets the Pacific plate.

This location makes it an example of an ophiolite. An ophiolite is a section of the Earth's oceanic crust and the underlying upper mantle that has been pushed upward. The island shows rocks from the Earth's mantle that are actively exposed above sea level. This is the only place on Earth where a mid-ocean ridge does this.

The mechanism that created the island involved a change in plate movement. In earlier geologic time, the two tectonic plates were moving apart. This movement allowed lava from the Earth's mantle to rise to the seafloor. This lava formed basaltic rock. Later, the movement of the plates reversed. The plates began moving toward each other instead. This movement caused uplift along the Macquarie Ridge. Scientists describe this process as if the island were being squeezed toward the surface like toothpaste from a tube. The highest points may have emerged above the sea as recently as 300,000 years ago.

Human history on the island began in the early 19th century. Frederick Hasselborough, an Australian, discovered the uninhabited island on 11 July 1810. He was searching for new sealing grounds at the time. He claimed the island for Britain and annexed it to New South Wales. The island was named after Colonel Lachlan Macquarie, the Governor of New South Wales. In 1820, the Russian explorer Fabian Gottlieb von Bellingshausen produced the first map of the island. He landed there on 28 November 1820 to define its geographical position. He also traded food and rum for local fauna with the sealers.

The island's history also includes difficult times for its wildlife and visitors. Between 1810 and 1919, seals and penguins were hunted for their oil. This hunting almost led to their extinction. You can still see relics from this era, such as iron try pots and hut ruins.

The sea conditions were very harsh for sailors. Out of 144 recorded vessel visits, 12 ended in shipwrecks. In 1902, the Tasmanian Government leased the island to Joseph Hatch. He ran an oil industry based on harvesting penguins. Eventually, the island was protected as a wildlife sanctuary in 1933.

The climate of Macquarie Island is a tundra climate. This means the summers are very cold. The sea helps moderate the temperature so it rarely freezes. However, snow is common between May and November. It can even fall during the height of summer.

The island is one of the cloudiest places on Earth. It averages only 862 hours of sunshine each year. Most days are cloudy, with an average of 289.4 cloudy days annually. There are only about 3.5 clear days per year. This makes the environment very wet and damp.

Despite the harsh weather, the island supports much life. It is part of the Antipodes Subantarctic Islands tundra ecoregion. The entire royal penguin population comes here to nest during their annual season.

You can also find elephant seals in the area.

The island remains a vital place for scientific study and conservation. It connects our understanding of plate tectonics to the living world of the subantarctic.