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Pioneers Escarpment
Pioneers Escarpment (80°28′S 21°7′W / 80.467°S 21.117°W) is a mostly snow-covered north-facing escarpment in Antarctica, interrupted by occasional bluffs and spurs, between Slessor Glacier on the north and Shotton Snowfield on the south, in the Shackleton Range.
The escarpment was photographed from the air by the U.S. Navy, 1967, and was surveyed by British Antarctic Survey (BAS), 1968–71. It was named "Pioneers Escarpment" by the United Kingdom Antarctic Place-Names Committee (UK-APC) because features on the escarpment are named after the pioneers whose inventions have assisted living and traveling conditions in the polar regions. The escarpment was visited and the rocks sampled extensively for the first time during the Geologische Expedition in die Shackleton Range (GEISHA) expedition in 1987–88.
The outcroppings in the escarpment typically contain a succession of sedimentary rocks and rocks of volcanic origin which make up the Pioneers Group, a subcrustal unit. The metamorphic rocks of the Pioneers Group are a diverse series of metasedimentary rocks. Rock types include quartzites, mica schists, Al-rich schists and gneisses, calc-silicate schists, metalimestones and marbles, and amphibolites.
Most of the rock types found in the escarpment are metamorphosed from amphibolite facies, but cores of garnet contain traces of granulite facies. The metasedimentary rocks are from deposits that were laid down in shallow water on the submerged rim of a craton. During the peak of metamorphism both the sediments and the volcanics were subject to high pressures but relatively low temperatures of around 600 °C (1,112 °F). At this time they would have been as deep as 35 kilometres (22 mi), but were probably uplifted before the Ross orogeny 500 million years ago. Additional sedimentation occurred after this, creating non-metamorphic shales, sandstones and greywackes that may date to the Jurassic (200–145 million years ago).
Features of the escarpment and neighboring nunataks that are named on the 1983 United States Geological Survey map are (northwest to southeast):
80°25′S 23°16′W / 80.417°S 23.267°W Nunatak rising to 1,215 metres (3,986 ft) at the west end of Pioneers Escarpment, Shackleton Range. In association with the names of pioneers of polar life and travel grouped in this area, named by the UK-APC in 1971 after Major Frederick George Jackson (1860-1938), English Arctic explorer who in 1895 designed the features of the pyramid tent, later to become standard equipment on British polar expeditions.
Jackson Tooth has a visible band about 50 metres (160 ft) thick of medium grained marble, coloured light grey to white, containing tremolite. Below this is a band about 100 metres (330 ft) thick of grey marble, with up to 10% of its volume made up of star-like aggregates of chrysotile-asbestos. There may also be muscovite schists and muscovite quartzite holding accessory tourmaline, since rocks like this are seen about 2 kilometres (1.2 mi) north of the nunatak.
80°28′S 22°28′W / 80.467°S 22.467°W. Mountain rising to c. 1,400 metres (4,600 ft) to the west of Mount Kelsey in the Pioneers Escarpment, Shackleton Range. Photographed from the air by the U.S. Navy, 1967. Surveyed by the BAS, 1968-71. In association with the names of pioneers of polar life and travel grouped in this area, named by the UK-APC in 1971 after Adm. Sir Francis Leopold M'Clintock, RN (1819-1907), British Arctic explorer and pioneer in adopting Eskimo methods of overland travel; he took part in three Franklin search voyages, 1848–54, and commanded Fox, 1857-59, on the voyage to Arctic Canada that finally determined the fate of Sir John Franklin's expedition.
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Pioneers Escarpment
Pioneers Escarpment (80°28′S 21°7′W / 80.467°S 21.117°W) is a mostly snow-covered north-facing escarpment in Antarctica, interrupted by occasional bluffs and spurs, between Slessor Glacier on the north and Shotton Snowfield on the south, in the Shackleton Range.
The escarpment was photographed from the air by the U.S. Navy, 1967, and was surveyed by British Antarctic Survey (BAS), 1968–71. It was named "Pioneers Escarpment" by the United Kingdom Antarctic Place-Names Committee (UK-APC) because features on the escarpment are named after the pioneers whose inventions have assisted living and traveling conditions in the polar regions. The escarpment was visited and the rocks sampled extensively for the first time during the Geologische Expedition in die Shackleton Range (GEISHA) expedition in 1987–88.
The outcroppings in the escarpment typically contain a succession of sedimentary rocks and rocks of volcanic origin which make up the Pioneers Group, a subcrustal unit. The metamorphic rocks of the Pioneers Group are a diverse series of metasedimentary rocks. Rock types include quartzites, mica schists, Al-rich schists and gneisses, calc-silicate schists, metalimestones and marbles, and amphibolites.
Most of the rock types found in the escarpment are metamorphosed from amphibolite facies, but cores of garnet contain traces of granulite facies. The metasedimentary rocks are from deposits that were laid down in shallow water on the submerged rim of a craton. During the peak of metamorphism both the sediments and the volcanics were subject to high pressures but relatively low temperatures of around 600 °C (1,112 °F). At this time they would have been as deep as 35 kilometres (22 mi), but were probably uplifted before the Ross orogeny 500 million years ago. Additional sedimentation occurred after this, creating non-metamorphic shales, sandstones and greywackes that may date to the Jurassic (200–145 million years ago).
Features of the escarpment and neighboring nunataks that are named on the 1983 United States Geological Survey map are (northwest to southeast):
80°25′S 23°16′W / 80.417°S 23.267°W Nunatak rising to 1,215 metres (3,986 ft) at the west end of Pioneers Escarpment, Shackleton Range. In association with the names of pioneers of polar life and travel grouped in this area, named by the UK-APC in 1971 after Major Frederick George Jackson (1860-1938), English Arctic explorer who in 1895 designed the features of the pyramid tent, later to become standard equipment on British polar expeditions.
Jackson Tooth has a visible band about 50 metres (160 ft) thick of medium grained marble, coloured light grey to white, containing tremolite. Below this is a band about 100 metres (330 ft) thick of grey marble, with up to 10% of its volume made up of star-like aggregates of chrysotile-asbestos. There may also be muscovite schists and muscovite quartzite holding accessory tourmaline, since rocks like this are seen about 2 kilometres (1.2 mi) north of the nunatak.
80°28′S 22°28′W / 80.467°S 22.467°W. Mountain rising to c. 1,400 metres (4,600 ft) to the west of Mount Kelsey in the Pioneers Escarpment, Shackleton Range. Photographed from the air by the U.S. Navy, 1967. Surveyed by the BAS, 1968-71. In association with the names of pioneers of polar life and travel grouped in this area, named by the UK-APC in 1971 after Adm. Sir Francis Leopold M'Clintock, RN (1819-1907), British Arctic explorer and pioneer in adopting Eskimo methods of overland travel; he took part in three Franklin search voyages, 1848–54, and commanded Fox, 1857-59, on the voyage to Arctic Canada that finally determined the fate of Sir John Franklin's expedition.