Heard Island Expedition 1997 (Scoping Document)


[Illustration from Thornton, M., Ed. 1983. Heard Island Expedition 1983. Spirit of Adventure Pty. Ltd. ISBN 0 9592568 0 6. The text in this section was derived from the Heard Island Wilderness Reserve Management Plan, Australian Antarctic Division, Sept. 1995].

The combination of features-dramatic glaciated landscapes, abundant wildlife, geological history, and harsh weather conditions and the absence of any human introduction of non-indigenous species-makes this a region of outstanding natural values and can be readily recognized to have the inspiration qualities of a pristine wilderness.-AAD

Heard Island lies in the southern Indian Ocean at 53°05' S - 73°30' E. It has an area of 368 km2. Its principal feature is the intermittently active volcano Big Ben, peaking at 2745 m above sea level. Toward the Northwest is Laurens Peninsula, which is a subsidiary volcanic cone 715 m above sea level. The remaining areas are mainly narrow coastal flats at the western and eastern ends. The margin is characterized by coastal ice cliffs and exposed high-energy rocky beaches. Heard Island is biologically pristine: there is no record of any human-introduced species.

[Illustration from R. Headland, The Island of South Georgia]

Eleven vascular plants, most subAntarctic species, are known from HI. The major plant communities are tussock grassland, meadow, herbfield, pool complex, cushion carpet, and fellfield. So far, 42 species of mosses, 20 liverwort species, and more than 40 lichens have been identified. Ferns and terrestrial and freshwater algae are present, but have not been documented.

Seven species of seals occur at HI, of which the southern elephant seal is by far the most abundant. Most of the seals reside on the eastern side of the island. Twenty-four species of birds have been recorded, of which 19 are known to breed there. The avian fauna include penguins, skuas, sheathbills, albatross, petrels, and the Heard Island cormorant (which is endemic). As of April, 1995, the number of invertebrates known was 128, some of which are endemic. Some of the insects show clear evolutionary morphological modification consistent with the presumed isolation.

The marine biology is very poorly known, due to the difficult conditions for conducting research. A large brown alga forms large forests. The sub-littoral fauna is apparently of low diversity. The fish fauna is dominated by the Antarctic cods and icefish. Only 9 species have been recorded from shallow waters.

Meteorological conditions on Heard Island are highly variable. Temperatures during the Austral summer are slightly about 5°C (41°F). The winds at Atlas Cove are predominantly westerly, with mean speed 26 km/hr. December is the least windy month. Snowfalls occur year round, with the least (about 10 cm/month) occurring during the Austral summer. The average annual rainfall at Atlas Cove is 135 cm. The sun shines an average of about 2 hours per day in January.

Glacial ice covers more than 80 percent of Heard Island. These glaciers descend from Big Ben; they have steep surface slopes, are fast-flowing, and shallow. Movement in the center is typically about 250 m/yr. Average particle residence time in the glaciers is about 1090 years. Significant retreat of most glaciers has occurred in the last decade.

[Heard Island Wilderness Reserve Management Plan, Australian Antarctic Division, Sept. 1995].

HI sits on a limestone accumulation on the Kerguelen Plateau, dating to the middle Eocene to early Oligocene (i.e., ca. 40-30 MY B. P.). The two main volcanic centers (Big Ben and Mt. Dixon) produce two extremely different types of lava. Big Ben is a conical volcano 20 km in diameter at the base. It emits steam continuously, and the summit is warm to the touch. Morphologically, it is dominated by an avalanche amphitheater. Much of the volcano has slumped to the southwest, and the resultant cavity has been filled by later activity. Big Ben has been climbing twice, in 1965 and in 1983.
There is a variety of lava fields and volcanic ash deposits. There are alluvial features such as melt streams and karst features in limestone areas. Classic volcanic features include pahoehoe lava flows, spatter cones, ash cones, and lava tubes. In combination with glacial retreat, there are terminal lakes and moraines. Peat associated with vegetation occurs on the poorly drained low lying coastal areas.

Heard Island is one element in a larger Territory vested in the Commonwealth of Australia. The Territory includes Heard Island, the McDonald Islands, and various offshore rocks and shoals, and the territorial sea, totally 6364 km2. Heard Island was used by sealers from the mid-19th Century until 1929. In 1947 the first Australian National Antarctic Research Expedition (ANARE) set up a research station at Atlas Cove, and undertook the first detailed scientific survey of the island. The station was closed in 1955 and is now in ruins. Only 2 visits by small tourist parties have been made up to 1994. Considerable parts of Heard Island have not yet been visited by humans.

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Last update: 6 Oct. 1996 Robert W. Schmieder cordell@ccnet.com