The Antarctic Ice Sheet dominates the region. It is the largest single piece of ice on Earth. This ice sheet even extends beyond the continent when snow and ice are at their most extreme. The ice surface dramatically grows in size from about three million square kilometers at the end of summer to about 19 million square kilometers by winter. Ice sheet growth mainly occurs at the coastal ice shelves, primarily the Ross Ice Shelf and the Ronne Ice Shelf. Ice shelves are floating sheets of ice that are connected to the continent. Glacial ice moves from the continent’s interior to these lower-elevation ice shelves at rates of 10 to 1,000 metres per year.
Antarctica has a number of mountain summits, including the Transantarctic Mountains, which divide the continent into eastern and western regions. A few of these summits reach altitudes of more than 4,500 meters. The elevation of the Antarctic Ice Sheet itself is about 2,000 meters and reaches 4,000 meters above sea level near the center of the continent.
Without any ice, Antarctica would emerge as a giant peninsula and archipelago of mountainous islands, known as Lesser Antarctica, and a single large landmass about the size of Australia, known as Greater Antarctica. These regions have different geologies.
Greater Antarctica, or East Antarctica, is composed of older, igneous and metamorphic rocks. Lesser Antarctica, or West Antarctica, is made up of younger, volcanic and sedimentary rock. Lesser Antarctica, in fact, is part of the “Ring of Fire,” a tectonically active area around the Pacific Ocean. Tectonic activity is the interaction of plates on Earth’s crust, often resulting in earthquakes and volcanoes. Mount Erebus, located on Antarctica’s Ross Island, is the southernmost active volcano on Earth.
The majority of the islands and archipelagos of Lesser Antarctica are volcanic and heavily glaciated. They are also home to a number of high mountains.
The oceans surrounding Antarctica provide an important physical component of the Antarctic region. The waters surrounding Antarctica are relatively deep, reaching 4,000 to 5,000 meters in depth.Leer más
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