Question: When did the ocean in which Indira Mount is located become a thing?

full_context: Document 1: Mount Betty: Mount Betty is a small ridge overlooking the Ross Ice Shelf, on the north side of Bigend Saddle, at the north-eastern extremity of the Herbert Range in the Queen Maud Mountains of Antarctica. It was discovered in November 1911 by Captain Roald Amundsen, and named by him for Betty Andersson, nurse and housekeeper in the Amundsen family for many years.
Document 2: Southern Ocean: By way of his voyages in the 1770s, Captain James Cook proved that waters encompassed the southern latitudes of the globe. Since then, geographers have disagreed on the Southern Ocean's northern boundary or even existence, considering the waters as various parts of the Pacific, Atlantic, and Indian Oceans, instead. However, according to Commodore John Leech of the International Hydrographic Organization (IHO), this situation has no scientific sense since it has different ecosystem and life from the three oceans mentioned before and is located on a southern portion of Earth, hence the name of an ocean. This remains the current official policy of the IHO, since a 2000 revision of its definitions including the Southern Ocean as the waters south of the 60th parallel has not yet been adopted. Others regard the seasonally - fluctuating Antarctic Convergence as the natural boundary.
Document 3: Indira Gandhi: Indira Priyadarshini Gandhi (Hindustani: (ˈɪnːdɪrə ˈɡaːnd̪ɦi) (listen); née Nehru; 19 November 1917 -- 31 October 1984) was an Indian stateswoman and central figure of the Indian National Congress. She was the first and, to date, the only female Prime Minister of India. Indira Gandhi belonged to the Nehru -- Gandhi family and was the daughter of Jawaharlal Nehru, the first Indian prime minister. Despite her surname Gandhi, she is not related to the family of Mahatma Gandhi. She served as Prime Minister from January 1966 to March 1977 and again from January 1980 until her assassination in October 1984, making her the second longest - serving Indian prime minister after her father.
Document 4: Borders of the oceans: The Southern Ocean did not appear in the 1953 third edition because ``... the northern limits... are difficult to lay down owing to their seasonal change... Hydrographic Offices who issue separate publications dealing with this area are therefore left to decide their own northern limits. (Great Britain uses the Latitude of 55 ° South) ''. Instead, in the IHO 1953 publication, the Atlantic, Indian and Pacific Oceans were extended southward, the Indian and Pacific Oceans (which had not previously touched pre 1953, as per the first and second editions) now abutted at the meridian of South East Cape, and the southern limits of the Great Australian Bight and the Tasman Sea were moved northwards.
Document 5: Mount Melbourne: Mount Melbourne is a massive stratovolcano that makes up the projection of the coast between Wood Bay and Terra Nova Bay, in Victoria Land of Antarctica. It was discovered in 1841 by James Clark Ross, who named it for Lord Melbourne, British prime minister when the expedition was being planned.
Document 6: Wilkes Land: Wilkes Land is a large district of land in eastern Antarctica, formally claimed by Australia as part of the Australian Antarctic Territory, though the validity of this claim has been placed for the period of the operation of the Antarctic Treaty, to which Australia is a signatory. It fronts on the southern Indian Ocean between Queen Mary Coast and Adelie Land, extending from Cape Hordern in 100°31' E to Pourquoi Pas Point, in 136°11' E. The region extends as a sector about 2600 km towards the South Pole, with an estimated land area of 2,600,000 km², mostly glaciated. It is further subdivided in the following coastal areas which can also be thought of as sectors extending to the South Pole:
Document 7: Antarctica: Explorer James Clark Ross passed through what is now known as the Ross Sea and discovered Ross Island (both of which were named after him) in 1841. He sailed along a huge wall of ice that was later named the Ross Ice Shelf. Mount Erebus and Mount Terror are named after two ships from his expedition: HMS Erebus and Terror. Mercator Cooper landed in East Antarctica on 26 January 1853.During the Nimrod Expedition led by Ernest Shackleton in 1907, parties led by Edgeworth David became the first to climb Mount Erebus and to reach the South Magnetic Pole. Douglas Mawson, who assumed the leadership of the Magnetic Pole party on their perilous return, went on to lead several expeditions until retiring in 1931. In addition, Shackleton and three other members of his expedition made several firsts in December 1908 – February 1909: they were the first humans to traverse the Ross Ice Shelf, the first to traverse the Transantarctic Mountains (via the Beardmore Glacier), and the first to set foot on the South Polar Plateau. An expedition led by Norwegian polar explorer Roald Amundsen from the ship Fram became the first to reach the geographic South Pole on 14 December 1911, using a route from the Bay of Whales and up the Axel Heiberg Glacier. One month later, the doomed Scott Expedition reached the pole.
Document 8: Southern Ocean: The Southern Ocean, geologically the youngest of the oceans, was formed when Antarctica and South America moved apart, opening the Drake Passage, roughly 30 million years ago. The separation of the continents allowed the formation of the Antarctic Circumpolar Current.
Document 9: Heard Island and McDonald Islands: The Territory of Heard Island and McDonald Islands (HIMI) is an Australian external territory comprising a volcanic group of barren Antarctic islands, about two-thirds of the way from Madagascar to Antarctica. The group's overall size is in area and it has of coastline. Discovered in the mid-19th century, the islands have been an Australian territory since 1947 and contain the country's two only active volcanoes. The summit of one, Mawson Peak, is higher than any mountain on the Australian mainland. The islands lie on the Kerguelen Plateau in the Indian Ocean.
Document 10: Amundsen Sea: The Amundsen Sea, an arm of the Southern Ocean off Marie Byrd Land in western Antarctica, lies between Cape Flying Fish (the northwestern tip of Thurston Island) to the east and Cape Dart on Siple Island to the west. Cape Flying Fish marks the boundary between the Amundsen Sea and the Bellingshausen Sea. West of Cape Dart there is no named marginal sea of the Southern Ocean between the Amundsen and Ross Seas. The Norwegian expedition of 1928–1929 under Captain Nils Larsen named the body of water for the Norwegian polar explorer Roald Amundsen while exploring this area in February 1929.
Document 11: Indira Mount: Indira Mount is a seabed mountain in the Antarctic Ocean (also known as the Southern Ocean). It was discovered during the First Indian Expedition to Antarctica (1981–82) when the team was moving from Mauritius to Antarctica. It was named as Indira Mount after the former Prime Minister of India Mrs Indira Gandhi by the expedition members.
Document 12: Iselin Seamount: Iselin Seamount is a seamount in the Southern Ocean off Antarctica. It was named for the research ship "Iselin II" of the Woods Hole Oceanographic Institute, the name being approved by the Advisory Committee for Undersea Features in February 1964.
Document 13: Antarctica: Positioned asymmetrically around the South Pole and largely south of the Antarctic Circle, Antarctica is the southernmost continent and is surrounded by the Southern Ocean; alternatively, it may be considered to be surrounded by the southern Pacific, Atlantic, and Indian Oceans, or by the southern waters of the World Ocean. It covers more than 14,000,000 km2 (5,400,000 sq mi), making it the fifth-largest continent, about 1.3 times as large as Europe. The coastline measures 17,968 km (11,165 mi) and is mostly characterized by ice formations, as the following table shows:
Document 14: Cape of Good Hope: A common misconception is that the Cape of Good Hope is the southern tip of Africa. This misconception was based on the misbelief that the Cape was the dividing point between the Atlantic and Indian Oceans. Contemporary geographic knowledge instead states the southernmost point of Africa is Cape Agulhas about 150 kilometres (90 mi) to the east - southeast. The currents of the two oceans meet at the point where the warm - water Agulhas current meets the cold water Benguela current and turns back on itself. That oceanic meeting point fluctuates between Cape Agulhas and Cape Point (about 1.2 kilometres (0.75 mi) east of the Cape of Good Hope).
Document 15: Cooperation Sea: The Cooperation Sea was named in 1962 by the Soviet Antarctic Expedition in honor of international science cooperation in Antarctica. The name first appeared as a proposal to the IHO in the IHO 2002 draft. This draft was never approved by the IHO (or any other organization), and the 1953 IHO document (which does not contain the name) remains currently in force. Leading geographic authorities and atlases do not use the name, including the 2014 10th edition of the World Atlas from the United States' National Geographic Society and the 2014 12th edition of the British Times Atlas of the World. But Soviet and Russian-issued maps do.
ground_truth: the 1770s
sub_queries: Indira Mount >> located on terrain feature Answer: Southern Ocean
when did Southern Ocean become a thing Answer: the 1770s