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#Glaciology, ablation over many years, often Century, centuries. It acquires dis ...

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 ...

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 ...

. 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-small ...

, 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 Ninnis Glacier () is a large, heavily hummocked and crevassed glacier descending steeply from the high interior to the sea in a broad valley, on George V Coast in Antarctica. It was discovered by the Australasian Antarctic Expedition (1911–14) ...

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, Ice ...

where it continues as a large glacier tongue out between

Cape De la Motte Cape De la Motte is a prominent cape in George V Land in Antarctica separating Watt Bay and Buchanan Bay. Just to the south, the continental ice surface rises at Mount Hunt. The cape was charted by the Australasian Antarctic Expedition (1911–14 ...

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 Fisher Bay is an embayment about wide between the eastern side of the Mertz Glacier Tongue and the mainland of Antarctica. It was discovered by the Australasian Antarctic Expedition (1911–14) under Douglas Mawson, who named it for Andrew Fish ...

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 (1911–14) under Douglas Mawson, 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

, 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 Iceberg B-9 was an iceberg that calved from Antarctica in 1987. It measured long and wide; it had a total area of , and is one of the longest icebergs ever recorded. This calving took place immediately east of the future calving site of Icebe ...

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 hi ...

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 An iceberg is a piece of freshwater ice more than 15 m long that has broken off a glacier or an ice shelf and is floating freely in open (salt) water. Smaller chunks of floating glacially-derived ice are called "growlers" or "bergy bits". The ...

, 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 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 temper ...

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 Int ...

(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 th ...

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.

References

External links