Ross Sea

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The Ross Sea is a deep bay of the Southern Ocean in Antarctica, between Victoria Land and Marie Byrd Land and within the Ross Embayment. It derives its name from the British explorer James Ross who visited this area in 1841. To the west of the sea lies Ross Island and Victoria Land, to the east Roosevelt Island and Edward VII Peninsula in Marie Byrd Land, while the southernmost part is covered by the Ross Ice Shelf, and is about 200 miles (320 km) from the South Pole. Its boundaries and area have been defined by the New Zealand National Institute of Water and Atmospheric Research as having an area of 637,000 square kilometres (246,000 sq mi).

The underlying rocks are of upper Precambrian to lower Paleozoic age and are partly composed of calcium carbonate. The circulation of the Ross Sea is dominated by a wind-driven ocean gyre and the flow is strongly influenced by three submarine ridges that run from southwest to northeast. The circumpolar deep water current is a relatively warm, salty and nutrient-rich water mass that flows onto the continental shelf at certain locations. The Ross Sea is covered with ice for most of the year.

The nutrient-laden water supports an abundance of plankton and this encourages a rich marine fauna. At least ten mammal species, six bird species and 95 fish species are found here, as well as many invertebrates, and the sea remains relatively unaffected by human activities. New Zealand has claimed that the sea comes under their jurisdiction as part of the Ross Dependency. Marine biologists consider the sea to have a high level of biological diversity and it is the site of much scientific research. It is also the focus of some environmentalist groups who have campaigned to have the area proclaimed as a world marine reserve.

The Ross Sea was discovered by James Ross in 1841. In the west of the Ross Sea is Ross Island with the Mt. Erebus volcano, in the east Roosevelt Island. The southern part is covered by the Ross Ice Shelf. Roald Amundsen started his South Pole expedition in 1911 from the Bay of Whales, which was located at the shelf. In the west of the Ross sea, McMurdo Sound is a port which is usually free of ice during the summer. The southernmost part of the Ross Sea is Gould Coast, which is approximately two hundred miles from the geographic South Pole.

The Ross Sea (and Ross Ice Shelf) overlies a deep continental shelf. Although the average depth of the world’s continental shelves (at the shelf break joining the continental slope) is about 130 meters, the Ross shelf average depth is about 500 meters. It is shallower in the western Ross Sea (east longitudes) than the east (west longitudes). This overdeepened condition is due to cycles of erosion and deposition of sediments from expanding and contracting ice sheets overriding the shelf since Oligocene time, and is also found on other locations around Antarctica. Erosion was more focused on the inner parts of the shelf while deposition of sediment dominated the outer shelf, making the inner shelf deeper than the outer.

Ross System rocks are of upper Precambrian to lower Paleozoic age and each group of Ross System have an echelon vein pattern demonstrating possible dextral faulting. These miogeosyncline metasedimentary rocks are usually folded about northwest and southeast axes and are partly composed of calcium carbonate, often including limestone. Groups within the Ross System include the Robertson Bay Group, Priestley Group, Skelton Group, Beardmore Group, Byrd Group, Queen Maud Group, and Koettlitz Group. The Robertson Bay Group ranges from 56 to 76% silica and compares closely with other Ross System members. The Priestley Group rocks are similar to those of the Robertson Bay Group and include dark slates, argillites, siltstones, fine sandstones and limestones. They can be found near the Priestley and Campbell glaciers. For thirty miles along the lower Skelton Glacier are the calcareous greywackes and argillites of the Skelton Group. The region between the lower Beardmore Glacier and the lower Shackelton Glacier sits the Beardmore Group. North of the Nimrod Glacier are four block faulted ranges that make up the Byrd Group. The contents of the Queen Maud Group area are mainly post-tectonic granite.

This page was last edited on 10 May 2018, at 16:25.
Reference: https://en.wikipedia.org/wiki/Ross_Sea under CC BY-SA license.

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