Mertz Glacier
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Mertz Glacier () is a heavily crevassed
glacier A glacier (; ) is a persistent body of dense ice that is constantly moving under its own weight. A glacier forms where the accumulation of snow exceeds its ablation over many years, often centuries. It acquires distinguishing features, such a ...
in
George V Coast George V Coast () is that portion of the coast of Antarctica lying between Point Alden, at 148°2′E, and Cape Hudson, at 153°45′E. Portions of this coast were sighted by the US Exploring Expedition in 1840. It was explored by members of t ...
of
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 almos ...
. It is the source of a glacial prominence that historically has extended northward into the
Southern Ocean The Southern Ocean, also known as the Antarctic Ocean, comprises the southernmost waters of the World Ocean, generally taken to be south of 60° S latitude and encircling Antarctica. With a size of , it is regarded as the second-smal ...
, the ''Mertz Glacial Tongue''. It is named in honor of the Swiss explorer Xavier Mertz. The Mertz-Ninnis Valley () is an undersea valley named in association with the Mertz Glacier and the Ninnis Glacier.


Geography

Mertz Glacier is about 45 miles (72 km) long and averaging 20 miles (32 km) wide. It reaches the sea at the head of a 60 km
fjord In physical geography, a fjord or fiord () is a long, narrow inlet with steep sides or cliffs, created by a glacier. Fjords exist on the coasts of Alaska, Antarctica, British Columbia, Chile, Denmark, Germany, Greenland, the Faroe Islands, Icel ...
where it continues as a large glacier tongue out between Cape De la Motte/
Buchanan Bay Buchanan Bay is an Arctic waterway in Qikiqtaaluk Region, Nunavut, Canada. It is located in Nares Strait by eastern Ellesmere Island. The bay is bordered by Cape Camperdown on Bache Peninsula to the north, Cape Rutherford on Johan Peninsula to the ...
on the West, and Cape Hurley/ Fisher Bay on the east, into the Southern Ocean. The Mertz Glacier Tongue () is about 50 miles (80 km) long in total hence it protrudes about 20–25 km out into the Ocean. It is roughly 25 miles (40 km) wide. The Glacier delivers about 10 to 12 Gigatons of ice per year to the fjord and the Tongue advances at about 1 km per year down the fjord and out into the Ocean.


History

The glacier was discovered by the
Australasian Antarctic Expedition The Australasian Antarctic Expedition was a 1911–1914 expedition headed by Douglas Mawson that explored the largely uncharted Antarctic coast due south of Australia. Mawson had been inspired to lead his own venture by his experiences on Ernest ...
(1911–14) under
Douglas Mawson Sir Douglas Mawson OBE FRS FAA (5 May 1882 – 14 October 1958) was an Australian geologist, Antarctic explorer, and academic. Along with Roald Amundsen, Robert Falcon Scott, and Sir Ernest Shackleton, he was a key expedition leader duri ...
, who named it for Xavier Mertz, a member of the expedition who lost his life on January 7, 1913, on the far-east sledge journey. Mertz's body likely remains in the glacier that bears his name, a few miles closer to the Southern Ocean than when he was buried in the ice by Mawson.


2010 calving

In February 2010 about half of the Mertz Glacier Tongue, a piece of ice about long and wide and protruding out into the
Southern Ocean The Southern Ocean, also known as the Antarctic Ocean, comprises the southernmost waters of the World Ocean, generally taken to be south of 60° S latitude and encircling Antarctica. With a size of , it is regarded as the second-smal ...
, broke away from the main body of the Tongue. The separation occurred around the 12 or 13 February along two existing rift lines on opposite sides of the Tongue. The event was helped in part when the large Iceberg B-9B collided with it. Iceberg B-9B is a long by wide remnant of Iceberg B-9 which broke off 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 h ...
in 1987 and has recently ungrounded itself from Ninnis Bank to the east of the Tongue where it had been lodged for 18 years. The newly formed iceberg has been named Iceberg C-28, because it is the 28th substantial iceberg to have broken off the Antarctic ice shelf, in the quadrant that faces Australia, since 1976. The iceberg is high, has a surface area of and weights in at about 860 billion tonnes. According to Australian glaciologist Neal Young, such an event occurs once in 50 to 100 years. As the Tongue advances at 1 km per year this new iceberg represents about 70 years of glacier advance. Within 2 weeks the Mertz Iceberg rotated about the point of impact with B9-B and lay parallel with the coastline. The iceberg drifted westwards after the collision and in April 2010 hit a submerged peak which caused it to break into two pieces. The flow of icebergs from the calved glacier tongue has reduced the effectiveness of the
polynya A polynya () is an area of open water surrounded by sea ice. It is now used as a geographical term for an area of unfrozen seawater within otherwise contiguous pack ice or fast ice. It is a loanword from the Russian полынья (), which r ...
west of Mertz Glacier that acted as one of Antarctica's major areas for the formation of dense Antarctic Bottom Water. The calving could affect future
thermohaline Thermohaline circulation (THC) is a part of the large-scale ocean circulation that is driven by global density gradients created by surface heat and freshwater fluxes. The adjective ''thermohaline'' derives from '' thermo-'' referring to tem ...
circulation around Antarctica.


Important Bird Area

A 641 ha site on fast ice near the northern, or terminal, edge of the glacier toe has been designated an
Important Bird Area An Important Bird and Biodiversity Area (IBA) is an area identified using an internationally agreed set of criteria as being globally important for the conservation of bird populations. IBA was developed and sites are identified by BirdLife Inte ...
(IBA) by
BirdLife International BirdLife International is a global partnership of non-governmental organizations that strives to conserve birds and their habitats. BirdLife International's priorities include preventing extinction of bird species, identifying and safeguarding ...
because it supports a colony of
emperor penguin The emperor penguin (''Aptenodytes forsteri'') is the tallest and heaviest of all living penguin species and is endemic to Antarctica. The male and female are similar in plumage and size, reaching in length and weighing from . Feathers of t ...
s. Since its original identification in 2009, and the split of the tongue in 2010, the colony split into two sub-colonies about 20 km apart, with a ground census estimating some 5,100 breeding pairs in the western colony and 2,300 breeding pairs in the eastern.


See also

*
Ice stream An ice stream is a region of fast-moving ice within an ice sheet. It is a type of glacier, a body of ice that moves under its own weight. They can move upwards of a year, and can be up to in width, and hundreds of kilometers in length. They t ...
*
List of glaciers in the Antarctic There are many glaciers in the Antarctic. This set of lists does not include ice sheets, ice caps or ice fields, such as the Antarctic ice sheet, but includes glacial features that are defined by their flow, rather than general bodies of ice. ...
* List of Antarctic ice streams *
Petermann Glacier Petermann Glacier ( da, Petermann Gletsjer) is a large glacier located in North-West Greenland to the east of Nares Strait. It connects the Greenland ice sheet to the Arctic Ocean at 81°10' north latitude, near Hans Island. The glacier and its ...
*
Wilkins Sound Wilkins Sound is a seaway in Antarctica that is largely occupied by the Wilkins Ice Shelf. It is located on the southwest side of the Antarctic Peninsula between the concave western coastline of Alexander Island and the shores of Charcot Island ...


References


External links

* {{Portal bar, Birds, Water, Geography, Earth sciences, Weather Important Bird Areas of Antarctica Penguin colonies Ice streams of Antarctica Bodies of ice of George V Land