East Wallabi Island

East Wallabi Island is an island in the Wallabi Group of the Houtman Abrolhos, located in the Indian Ocean off the west coast of mainland Australia.

East Wallabi Island
Satellite image
Geography
LocationIndian Ocean, off the coast of Western Australia
Coordinates28°26′23″S 113°43′33″E[1][2]
ArchipelagoHoutman Abrolhos
Area3.21 km2 (1.24 sq mi)
Length3.3 km (2.05 mi)
Width1.8 km (1.12 mi)
Highest elevation15 m (49 ft)
Highest pointFlag Hill
Administration
Australia
StateWestern Australia
Demographics
PopulationUninhabited

History

East Wallabi Island played an important role in the story of the Batavia shipwreck and massacre. Following the shipwreck, a group of soldiers under the command of Wiebbe Hayes were put ashore on West Wallabi Island to search for water. The mutineers who took control of the ship left them there in the hope that they would starve or die of thirst. However, the soldiers discovered that they were able to wade to East Wallabi Island, where they eventually discovered a fresh water spring. Furthermore, West and East Wallabi Island are the only islands in the group upon which the tammar wallabi lives. Thus the soldiers had access to sources of both food and water that were unavailable to the mutineers.

In the context of the Batavia mutiny and massacre, East Wallabi Island is often referred to as "High island". This was the name given it in contemporary sources, and was used by historians for as long as it remained a lost toponym.

Geography
The Wallabi Group (excluding North Island) from space

Nominally located at 28°26′23″S 113°43′33″E,[1][2] East Wallabi Island is the second-largest island in Houtman Abrolhos archipelago, after West Wallabi Island. It is roughly circular in shape, except for Fish Point in the north-east. It is approximately 3.3 kilometres (2.1 mi) long (along the south-eastern edge) and about 1.8 kilometres (1.1 mi) wide,[3] giving it an area of about 321 hectares (790 acres).[4]

There are two named hills on the island. Flag Hill is located in the north-east of the island, at the foot of Fish Point; at 15 metres (49 ft), it is the highest point in the Houtman Abrolhos. In the south-east is another hill, named Eagle Hill. Other named localities include Fish Point and, on the point's western side, Turtle Bay. Immediately to the west of Flag Hill is an airstrip.

The island is surrounded by submerged coral reef. This is narrow along the west, north and east shores, giving way to open ocean to the west and north. Beyond the reef on the east side of the island lies Pigeon Island Anchorage, the main passage and anchorage for Pigeon Island, a small island 1 kilometre (0.62 mi) to the south that is used as a seasonal camp for the Western Rock Lobster fishery. To the south, the reef is extensive, and much of it is high enough that a person may wade from island to island; islands connected to East Wallabi Island in this way include Barge Rock, Turnstone Island, Seagull Island, Oystercatcher Island and West Wallabi Island.

Geology and physiography

The basement of East Wallabi Island is the Wallabi Limestone, a dense calcretised, coral limestone platform that underlies the entire Wallabi Group. This platform, which arises abruptly from a flat shelf, is about 40 metres (130 ft) thick, and is of Quaternary origin. Reef that formed during the Eemian interglacial (about 125,000 years ago), when sea levels were higher than at present, are now emergent in places, and constitute the basement of the group's central platform islands, which include East Wallabi Island.[5][6]

The basement is capped by aeolianite. This ranges from one to three metres (3 ft 3 in to 9 ft 10 in) thick, and forms an almost continuous pavement on the western half of the island. The aeolianite is in turn overlain by sand dunes. These are discontinuous in western and northern parts of the island, but in the south-west and east they are extensive and consolidated.[6][7]

Flora
See also: Flora of the Houtman Abrolhos

As one of the few islands in the Houtman Abrolhos large enough to support dune systems, East Wallabi Island supports a relatively high diversity of plant life. Both the dunes and the pavement limestone support species-rich vegetation complexes dominated by chenopod shrubs, and these communities have been identified as having species conservation importance, because they are so diverse, yet so easily disturbed and so slow to recover.

According to a survey published in 2001, 124 plant species occur on East Wallabi Island, the most of any island in the archipelago:[4]

Birds

The island is part of the Houtman Abrolhos Important Bird Area, identified as such by BirdLife International because of its importance for supporting large numbers of breeding seabirds.[8]

References
  1. Gazetteer of Australia (1996). Belconnen, ACT: Australian Surveying and Land Information Group.
  2. "East Wallabi Island". Gazetteer of Australia online. Geoscience Australia, Australian Government.
  3. Google Earth. Retrieved on 2009-01-17.
  4. Harvey, J. M., Alford, J. J., Longman, V. M. and Keighery, G. J. (2001). "A flora and vegetation survey of the Houtman Abrolhos, Western Australia". CALMScience. 3 (4): 521–623.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  5. Collins, Lindsay B.; Zhu, Zhong Rong; Wyrwoll, Karl-Heinz (1998). "Late Tertiary-Quaternary Geological Evolution of the Houtman Abrolhos Carbonate Platforms, Northern Perth Basin". In Purcell, R.; Purcell, P. (eds.). The sedimentary basins of Western Australia. Vol. 2. Perth, Western Australia: Petroleum Exploration Society of Australia. pp. 647–663. Archived from the original on 2008-07-22. Retrieved 2008-05-02.
  6. Collins, Lindsay B.; Zhu, Zhong Rong; Wyrwoll, Karl-Heinz (2004). "Geology of the Houtman Abrolhos Islands". In Vacher, Leonard; Quinn, Terrence (eds.). Geology and hydrogeology of carbonate islands (Developments in Sedimentology 54). Elsevier Science. pp. 811–834. ISBN 9780444516442.
  7. Storr, Glenn (1964). "The physiography, vegetation and vertebrate fauna of the Wallabi Group, Houtman Abrolhos". Journal of the Royal Society of Western Australia. 48 (1): 1–14.
  8. "IBA: Houtman Abrolhos". Birdata. Birds Australia. Archived from the original on 2011-07-06. Retrieved 2011-08-12.
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