Map_of_Antarctica_showing_outline_of_Ross_Embayment

The Ross Embayment is a large region of

Antarctica Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean, it contains the geographic South Pole. Antarctica is the fifth-largest contine ...

, comprising the

Ross Ice Shelf The Ross Ice Shelf is the largest ice shelf of Antarctica (, an area of roughly and about across: about the size of France). It is several hundred metres thick. The nearly vertical ice front to the open sea is more than long, and between hi ...

and the

Ross Sea 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, and is the southernmost sea on Earth. It derives its name from the British explorer James Clark Ross who vi ...

, that lies between East and West Antarctica.

Extent

The continent of

has two major divisions;

West Antarctica West Antarctica, or Lesser Antarctica, one of the two major regions of Antarctica, is the part of that continent that lies within the Western Hemisphere, and includes the Antarctic Peninsula. It is separated from East Antarctica by the Transant ...

in mostly western longitudes and

East Antarctica East Antarctica, also called Greater Antarctica, constitutes the majority (two-thirds) of the Antarctic continent, lying on the Indian Ocean side of the continent, separated from West Antarctica by the Transantarctic Mountains. It lies almost ...

in mostly eastern longitudes. East Antarctica is the larger and has a higher average elevation. Separating the two subcontinents is a lower elevation topographic region occupied by the Ross Ice Shelf and the Ross Sea. This region is referred to as the Ross Embayment. The embayment comprises an area of approximately . It includes the

() and the

(as of 2013, ). The name is most commonly used in the scientific literature, at times along with the

West Antarctic Rift System The West Antarctic Rift System is a series of rift valleys between East and West Antarctica. It encompasses the Ross Embayment, the Ross Sea, the area under the Ross Ice Shelf and a part of Marie Byrd Land in West Antarctica, reaching to the b ...

, which is of larger extent and has geologic meaning. Because the rift system includes the embayment, the latter is considered to lie in West Antarctica. The informal use of the name 'Ross Embayment' tends to denote a smaller region than the rift system. The embayment extends from Northern Victoria Land and the

Transantarctic Mountains The Transantarctic Mountains (abbreviated TAM) comprise a mountain range of uplifted (primarily sedimentary rock, sedimentary) rock in Antarctica which extend, with some interruptions, across the continent from Cape Adare in northern Victoria La ...

on the west (in East Antarctica) to the

Edward VII Peninsula King Edward VII Land or King Edward VII Peninsula is a large, ice-covered peninsula which forms the northwestern extremity of Marie Byrd Land in Antarctica. The peninsula projects into the Ross Sea between Sulzberger Bay and the northeast corne ...

Shirase Coast Shirase Coast () is the north segment of the relatively ill-defined coast along the east side of Ross Ice Shelf and Ross Sea, lying between the north end of Siple Coast (about ) and Cape Colbeck. Named by NZ-APC in 1961 after Lieutenant Nobu Shiras ...

, and

Siple Coast Siple Coast () is the middle portion of the relatively ill-defined coast along the east side of the Ross Ice Shelf, between the north end of Gould Coast () and the south end of Shirase Coast (). The area was originally called Kirton Coast, but was ...

on the east (

Marie Byrd Land Marie Byrd Land (MBL) is an unclaimed region of Antarctica. With an area of , it is the largest unclaimed territory on Earth. It was named after the wife of American naval officer Richard E. Byrd, who explored the region in the early 20th centur ...

in West Antarctica), and south to the

grounding line Marine ice sheet instability (MISI) describes the potential for ice sheets grounded below sea level to destabilize in a runaway fashion. The mechanism was first proposed in the 1970s by Johannes Weertman and was quickly identified as a means by wh ...

of the Ross Ice Shelf.

Formation

The low elevation marine characteristic of the Ross Embayment formed since the

Jurassic The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately Mya. The J ...

period. Before that time and earlier East and West Antarctica had similar elevations and the Ross Embayment did not exist. The breakup of the eastern sector of

Gondwana Gondwana () was a large landmass, often referred to as a supercontinent, that formed during the late Neoproterozoic (about 550 million years ago) and began to break up during the Jurassic period (about 180 million years ago). The final stages ...

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of th ...

time resulted in crustal extension, thinning and subsidence to form the Ross Embayment. The mechanism of crustal stretching and subsidence in the Ross Embayment has been attributed to

detachment fault A detachment fault is a gently dipping normal fault associated with large-scale extensional tectonics. Detachment faults often have very large displacements (tens of km) and juxtapose unmetamorphosed hanging walls against medium to high-grade me ...

ing. Extension between East and West Antarctica totals about 500 kilometers. Half of this occurred prior to

sea floor spreading Seafloor spreading or Seafloor spread is a process that occurs at mid-ocean ridges, where new oceanic crust is formed through volcanic activity and then gradually moves away from the ridge. History of study Earlier theories by Alfred Wegener an ...

that separated the New Zealand microcontinents (

Zealandia Zealandia (pronounced ), also known as (Māori) or Tasmantis, is an almost entirely submerged mass of continental crust that subsided after breaking away from Gondwanaland 83–79 million years ago.Gurnis, M., Hall, C.E., and Lavier, L.L., ...

) from Antarctica beginning at 85 million years. The remaining extension occurred in the Central Trough, Northern Basin, and

Victoria Land Basin Victoria most commonly refers to: * Victoria (Australia), a state of the Commonwealth of Australia * Victoria, British Columbia, provincial capital of British Columbia, Canada * Victoria (mythology), Roman goddess of Victory * Victoria, Seychelle ...

in the western Ross Sea before late Miocene time. Subsidence continued as mantle under the Ross Embayment cooled.

References

{{reflist Landforms of Antarctica

Extent

Formation

See also

References