Macquarie Island
Macquarie Island (34 km long x 5 km wide) is an oceanic island in the Southern Ocean, lying 1,500 km south-east of Tasmania and approximately halfway between Australia and the Antarctic continent. The island is the exposed crest of the undersea Macquarie Ridge, raised to its present position where the Indo-Australian tectonic plate meets the Pacific plate. It is a site of major geoconservation significance, being the only place on earth where rocks from the earth’s mantle (6 km below the ocean floor) are being actively exposed above sea-level. These unique exposures include excellent examples of pillow basalts and other extrusive rocks.
Macquarie Island (34 km long x 5 km wide) is an oceanic island in the Southern Ocean, lying 1,500 km south-east of Tasmania and approximately halfway between Australia and the Antarctic continent. The island is the exposed crest of the undersea Macquarie Ridge, raised to its present position where the Indo-Australian tectonic plate meets the Pacific plate. It is a site of major geoconservation significance, being the only place on earth where rocks from the earth’s mantle (6 km below the ocean floor) are being actively exposed above sea-level. These unique exposures include excellent examples of pillow basalts and other extrusive rocks.
Outstanding Universal Value
Brief synthesis
Macquarie Island lies almost 1,500 kilometres to the southeast of Tasmania, about half-way between Australia and Antarctica. The property includes Macquarie Island, Judge and Clerk Islets 11 kilometres to the north, the Bishop and Clerk Islets 37 kilometres to the south, rocks, reefs and the surrounding waters to a distance of 12 nautical miles. The main island is approximately 34 kilometres long and 5.5 kilometres wide at its broadest point, covering an area of approximately 12,785 hectares. The property covers an area of 557,280 hectares.
Macquarie Island has outstanding universal value for two reasons. First, it provides a unique opportunity to study, in detail, geological features and processes of oceanic crust formation and plate boundary dynamics, as it is only place on earth where rocks from the earth’s mantle (6 kilometres below the ocean floor) are being actively exposed above sea level. These unique exposures include excellent examples of pillow basalts and other extrusive rocks. Second, its remote and windswept landscape of steep escarpments, lakes, and dramatic changes in vegetation provides an outstanding spectacle of wild, natural beauty complemented by vast congregations of wildlife including penguins and seals.
Criterion (vii): Macquarie Island provides an outstanding spectacle of wild, natural beauty with huge congregations of penguins and seals populating what has been described as a small speck thrust up into the vast Southern Ocean. The island lies in latitudes known as the ‘Furious Fifties’ because of the frequency of very strong winds and stormy seas, which have sculpted the island. A coastal terrace supports vast waterlogged and heavily vegetated areas, forming a mire based on deep peat beds known as ‘featherbed’. This is framed by steep escarpments which rise spectacularly to a plateau surface dotted with innumerable lakes, tarns and pools. The continual westerly winds, which increase in force as they rise over the barrier of the island, and changes in topography result in dramatic changes in the vegetation cover which can vary from lush grassland to sparse feldmark within the space of a few metres.
Among the most aesthetically appealing features of the island are the vast congregations of wildlife, particularly penguins, during the breeding season. The breeding population of Royal Penguins (Eudyptes schlegeli), a species endemic to Macquarie Island and nearby Bishop and Clerk Islets, is estimated at over 850,000 pairs, one of the greatest congregations of seabirds in the world. The breeding population of King Penguins (Aptenodytes patagonicus), estimated at around 150,000–170,000 breeding pairs in 2000, is still expanding. As the King Penguin chicks do not leave the vicinity of the nest for a year, they survive the rigours of winter by huddling together on the windy and snow-swept beaches. Four species of albatross nest on steep and rugged cliffs and are easily viewed when nesting. Elephant Seals (Mirounga leonina) also form impressive colonies during the breeding season.
Criterion (viii): Macquarie Island and its outlying islets are geologically unique in being the only place on earth where rocks from the earth’s mantle are being actively exposed above sea level. The island is the exposed crest of the undersea Macquarie Ridge, raised to its present position where the Indo-Australian tectonic plate meets the Pacific plate. These unique exposures provide an exceptionally complete section of the structure and composition of both the oceanic crust and the upper mantle, and provide evidence of ‘sea-floor spreading’ and tectonic processes that have operated for hundreds of millions of years. The geological evolution of Macquarie Island began 10 million years ago and continues today with the island experiencing earthquakes and a rapid rate of uplift, all of which are related to active geological processes along the boundary between the two plates.
Sequences from all crustal levels, down to 6 kilometres below the ocean floor, are exposed as a result of tilting and differential uplift on Macquarie Island. This provides rare evidence for sequences that are common from the bottom of the oceans to the upper mantle, but not seen elsewhere in surface outcrops. The lack of deformation of this exposed crust is highly significant as it exhibits key interrelated and interdependent oceanic crustal elements in their natural relationship.
Macquarie Island is the only ophiolite (a well-developed and studied geological complex) recognised to have been formed within a major ocean basin. The geology of the island is therefore considered to be the connecting link between the ophiolites of continental environments and those located within the oceanic crust.
Integrity
The property is of sufficient size and contains the necessary elements to demonstrate the key aspects of the geological processes of Macquarie Island and the outlying Bishop and Clerk and Judge and Clerk islets. All major elements of the Macquarie deformational zone are included in the property.
Human impacts, commencing on Macquarie Island in 1810, have resulted in major changes to the biota of the reserve. The commercial exploitation of seals and penguins, together with the introduction of alien species, resulted in the extinction of some native species and major declines in others. Resultant modifications to vegetation associations and nutrient cycles severely impacted on some species while benefiting others.
Active management programmes, commenced in the 1960s, are aimed at stopping and/or reversing some of these trends. Some of these programmes have resulted in very rapid changes, including the eradication of feral cats and wekas from the island. However, the recovery of natural ecosystem processes as a result of these management programmes may take centuries. Macquarie Island is remote and well protected and managed.
Protection and management requirements
The property is vulnerable to the consequences of anthropogenic climate change. The other threat to the integrity of the property, which is monitored and managed, is the spread of introduced species and pathogens. A project to eradicate the remaining mammalian pest species (rabbits, black rats and mice) is underway, and is expected to be completed in 2016.
Macquarie Island, the adjacent islets of Judge and Clerk and Bishop and Clerk, and all surrounding waters out to three nautical miles, is managed as a nature reserve by the Tasmanian Parks and Wildlife Service (PWS). Management of the reserve is guided by the Macquarie Island Nature Reserve and World Heritage Area Management Plan 2006. Most of the waters out to 200 nautical miles to the east of the reserve are within the Macquarie Island Commonwealth Marine Reserve, which is managed by the Australian Government in cooperation with the PWS.
Overarching management of the World Heritage values occurs under national legislation, the Environment Protection and Biodiversity Conservation Act 1999 (the Act). All World Heritage properties in Australia are ‘matters of national environmental significance’ protected and managed under the Act. This Act is the statutory instrument for implementing Australia’s obligations under a number of multilateral environmental agreements, including the World Heritage Convention. By law, any action that has, will have or is likely to have a significant impact on the World Heritage values of a World Heritage property must be referred to the responsible Minister for consideration. Substantial penalties apply for taking such an action without approval. Once a heritage place is listed, the Act provides for the preparation of management plans which set out the significant heritage aspects of the place and how the values of the site will be managed.
Importantly, this Act also aims to protect matters of national environmental significance, such as World Heritage properties, from impacts even if they originate outside the property or if the values of the property are mobile (as in fauna). It thus forms an additional layer of protection designed to protect values of World Heritage properties from external impacts.
Long Description
Macquarie Island is an oceanic island in the Southern Ocean, lying 1,500 km south-east of Tasmania and approximately halfway between Australia and the Antarctic continent. The island is the exposed crest of the undersea Macquarie Ridge, raised to its present position where the Indo-Australian tectonic plate meets the Pacific plate. It is a site of major geo-conservation significance, being the only place where rocks from the Earth's mantle (6 km below the ocean floor) are being actively exposed above sea level.
It is the only island in the world composed entirely of oceanic crust and rocks from the Earth's mantle deep below the surface.
Macquarie Island probably began as a spreading ridge under the sea with the formation of new oceanic crust somewhere between 11 million and 30 million years ago.
At some stage the spreading halted and the crust began to compress, squeezing rocks upward from deep within the mantle. As the ridge grew it eventually became exposed above the ocean surface about 600,000 years ago. Thus, rocks normally only occurring deep within the Earth's mantle have become exposed on the surface.
Since Macquarie Island emerged, it has mainly been carved by marine processes such as wave action, unlike other subantarctic islands, which have been shaped by glaciers.
These unique exposures include excellent examples of pillow basalts and other extrusive rocks.
The main landscape feature is a central rolling plateau 250-300 m above sea level, bounded on all sides by steep cliffs, from the foot of which extends a coastal platform up to 800 m wide. Glacial drift up to 20 m thick covers much of the plateau and there are several lakes.
Among the most aesthetically appealing sights of the island are the vast congregations of wildlife, particularly penguins, on suitable parts of the coastal terrace, especially during breeding seasons.
During the breeding season on suitable beaches elephant seals also form impressive colonies. Four species of albatross nest on steep and rugged cliffs, both on the main island and on nearby Bishop and Clerk Islands.
The terrestrial area of Macquarie Island is a State Reserve with protection extending to low water mark. The marine values are protected by the Macquarie Island Marine Park declared by the Commonwealth on 28 October 1999. The primary purpose of the marine park is to protect the conservation values of the region from human disturbance. The marine park contains the world's largest marine highly protected zone, covering more than 16 million hectares.
Sealers discovered the island in 1810 and inhabited it periodically throughout the 19th century, exterminating the fur seals and greatly reducing the elephant seal population. In 1870, gangs came to exploit the king and royal penguin populations for oil, eliminating the former. The original elephant seal population of about 100,000 animals was reduced by 70% as a result of these operations. The visitors also brought exotic mammals and caused the extermination of two endemic subspecies of land birds.
There are no permanent human inhabitants on Macquarie Island although the Australian Antarctic Division station is occupied all year round. The only access to the island is by sea and there are no harbors or landing facilities, so ship-traffic in the area is minimal.
Source: UNESCO/CLT/WHC
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