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Adelaide Island

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Adelaide Island is a large, mainly ice-covered landmass in Antarctica. It is long and wide in shape. The island sits at the north side of Marguerite Bay. This location is off the west coast of the Antarctic Peninsula.

Antarctica (2), Adelaide Island, Mackay Point
Antarctica (2), Adelaide Island, Mackay Point

The Ginger Islands are located near the southern end of the island. Because of its location, the island lies within the Antarctic claims of Argentina, Chile, and the United Kingdom. It is a significant geographic feature in the Bellingshausen Sea.

The geology of the island reveals a history of intense volcanic activity. During the Mesozoic era, the Antarctic Peninsula was an active volcanic arc. This process involved the deposition of a fore-arc basin sequence. On the eastern part of the island, this sequence includes a 2 to 3 km succession of volcanic rocks and turbiditic coarse sandstones. These rocks are similar to the Fossil Bluff Group found on Alexander Island. The western portion of the island is covered by the Fuchs Ice Piedmont.

Different rock formations on the island represent different periods of Earth's history. The oldest is the Late Jurassic Buchia Buttress Formation, dating back 149.5 million years. This formation consists of volcanic breccias, tuffs, and volcaniclastic rocks mixed with sandstones and pebble conglomerates. Later, the Early Cretaceous Milestone Bluff Formation appeared 113.9 million years ago. This sandstone-conglomerate formation indicates a shallowing trend in the environment. Volcanic activity continued with the Bond Nunatak Formation at 75 million years.

Antarctica (2), Adelaide Island, Mackay Point
Antarctica (2), Adelaide Island, Mackay Point

Other volcanic structures add to the island's complex geological makeup. The Mount Leotard Formation formed between 75 and 65 million years ago. It contains up to 1800 m of hyaloclastites, breccias, and basaltic andesite lavas. The Reptile Ridge Formation is a rhyolitic ignimbrite that is up to 400 m thick. Finally, the Adelaide Island Intrusive Suite appeared between 45 and 52 million years ago. This suite consists of granodiorite-gabbro hybrid plutons and minor dolerite dykes.

Exploration of the island began in 1832 when John Biscoe led a British expedition. Biscoe discovered the island and named it for Queen Adelaide of the United Kingdom. Later, the French Antarctic Expedition surveyed the area from 1908 to 1910. This expedition was led by Jean-Baptiste Charcot. Charcot named many features, such as Cape Mascart, after the French physicist Éleuthère Mascart. He also named the southeast extremity Cape Alexandra after Queen Alexandra of Denmark.

Rothera from reptile
Rothera from reptile

Human activity on the island is centered around research stations. The Rothera Research Station is a major site that remains open today. It replaced the old Adelaide Island base, also known as Base T. That original base was run by the Falkland Islands Dependencies Survey. The station was moved during 1976-77 because the skiway was unstable. In 1984, the old British base was transferred to Chilean authorities. It was renamed the Teniente Luis Carvajal Villaroel Antarctic Base.

Rothera from reptile
Rothera from reptile

Today, the old Chilean base is used only during the summer. The Chilean Air Force has stopped operating there because the skiway and the ramp from the plateau are unstable. However, the Chilean Navy visits almost every summer to maintain the station. British Antarctic Survey employees also visit during the winter when plateau access is easier. The island is well mapped compared to other Antarctic locations due to this long history of habitation.

Many specific landmarks have been charted by various expeditions. Mackay Point is a small peninsula, 450 m wide at its widest point. It protrudes into Laubeuf Fjord from the Wormald Ice Piedmont.

Antarctica (2), Adelaide Island, Mackay Point
Antarctica (2), Adelaide Island, Mackay Point

Nearby, Rothera Point marks the east side of Ryder Bay. This point is an Antarctic Specially Protected Area, known as ASPA No. 129. It serves as a biological research site. Scientists monitor this fellfield ecosystem to study the environmental impact of the nearby Rothera Research Station.

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File:Rothera from reptile.jpg
Rothera from reptile.jpg
File:Antarctica_(2),_Adelaide_Island,_Mackay_Point.JPG
Antarctica_(2),_Adelaide_Island,_Mackay_Point.JPG
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