Armstrong Reef is a

reef A reef is a ridge or shoal of rock, coral or similar relatively stable material, lying beneath the surface of a natural body of water. Many reefs result from natural, abiotic processes— deposition of sand, wave erosion planing down rock out ...

that encompasses many ice-free

pluton In geology, an igneous intrusion (or intrusive body or simply intrusion) is a body of intrusive igneous rock that forms by crystallization of magma slowly cooling below the surface of the Earth. Intrusions have a wide variety of forms and com ...

ic islets and rocks, extending for from the south-west end of

Renaud Island Renaud Island is an ice-covered island in the Biscoe Islands of Antarctica, long and from (average ) wide, lying between the Pitt Islands and Rabot Island. It is separated from the Pitt Islands to the northeast by Mraka Sound, and from Lavoisi ...

, in the

Biscoe Islands Biscoe Islands is a series of islands, of which the principal ones are Renaud, Lavoisier (named ''Serrano'' by Chile and ''Mitre'' by Argentina), Watkins, Krogh, Pickwick and Rabot, lying parallel to the west coast of Graham Land and extending ...

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 ...

. It was first accurately shown on an

Argentine Argentines (mistakenly translated Argentineans in the past; in Spanish (masculine) or (feminine)) are people identified with the country of Argentina. This connection may be residential, legal, historical or cultural. For most Argentines, s ...

government chart of 1957, and was named by the

UK Antarctic Place-Names Committee The UK Antarctic Place-Names Committee (or UK-APC) is a United Kingdom government committee, part of the Foreign and Commonwealth Office, responsible for recommending names of geographical locations within the British Antarctic Territory (BAT) and ...

for Terence Armstrong, a British

sea ice Sea ice arises as seawater freezes. Because ice is less dense than water, it floats on the ocean's surface (as does fresh water ice, which has an even lower density). Sea ice covers about 7% of the Earth's surface and about 12% of the world's oce ...

specialist.

Important Bird Area

The reef has been identified as a 557 ha

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 ...

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 breeding colony of over 500 pairs of

Antarctic shag The Antarctic shag (''Leucocarbo bransfieldensis''), sometimes referred to as the imperial cormorant, king cormorant, imperial shag, blue-eyed shag or Antarctic cormorant, is the only species of the cormorant family found in the Antarctic. It is s ...

References

Reefs of Graham Land Landforms of the Biscoe Islands Important Bird Areas of Antarctica Seabird colonies {{Biscoes-geo-stub