Topgallant Islands is an island group in the Australian state of

South Australia South Australia (commonly abbreviated as SA) is a States and territories of Australia, state in the southern central part of Australia. With a total land area of , it is the fourth-largest of Australia's states and territories by area, which in ...

located in the

Investigator Group The Investigator Group is an archipelago in South Australia that consists of Flinders Island and five island groups located off the western coast of the Eyre Peninsula. It is named after by her commander, Matthew Flinders when he explored ...

about south west of Cape Finniss on the west coast of

Eyre Peninsula The Eyre Peninsula is a triangular peninsula in South Australia. It is bounded by the Spencer Gulf on the east, the Great Australian Bight on the west, and the Gawler Ranges to the north. Earlier called Eyre's Peninsula, it was named after e ...

. The group was discovered and named by

Matthew Flinders Captain (Royal Navy), Captain Matthew Flinders (16 March 1774 – 19 July 1814) was a British Royal Navy officer, navigator and cartographer who led the first littoral zone, inshore circumnavigate, circumnavigation of mainland Australia, then ...

on 13 February 1802. The island group has enjoyed

protected area Protected areas or conservation areas are locations which receive protection because of their recognized natural or cultural values. Protected areas are those areas in which human presence or the exploitation of natural resources (e.g. firewood ...

status since the 1960s and since 2011, it has been part of the

Investigator Group Wilderness Protection Area Investigator Group Wilderness Protection Area is a protected area in South Australia, located in the Investigator Group of islands off the west coast of Eyre Peninsula, between and south-west of Elliston. It was proclaimed in August 2011 u ...

Description

Topgallant Islands is an island group located about south west of Cape Finniss on the west coast of Eyre Peninsula in South Australia, about west by south of the town of Elliston and about east of

Flinders Island Flinders Island, the largest island in the Furneaux Group, is a island in the Bass Strait, northeast of the island of Tasmania. Today Flinders Island is part of the state of Tasmania, Australia. It is from Cape Portland, Tasmania, Cape Portl ...

.DMH, 1985, chart 38 The group consists of an islet and a number of bare rocks which are numbered at seven in one source and which extend from the islet in a line for a distance of about to the south east. The islet which has an area of about , is encircled by high cliffs and has a rounded top whose summit is at above sea level. The southernmost rock is reported as being a ‘sharp pyramid’ of height.Robinson, 1996, page 481 The name used for the island group varies from the name given by Flinders (i.e. Topgallant Isles) as follows: Topgallant Islands, Top-gallant Islands, Top-Gallant Isles and Top Gallant Isles. Access to Topgallant Island by boat is reported as not being possible due to a ‘combination of deep water swells, steep shores and sheer walls of rotten stone’. A survey carried in 1980 used a

helicopter A helicopter is a type of rotorcraft in which Lift (force), lift and thrust are supplied by horizontally spinning Helicopter rotor, rotors. This allows the helicopter to VTOL, take off and land vertically, to hover (helicopter), hover, and ...

to land personnel on the islet.Robinson et al, 1996, page 194Robinson et al, 1996, pages 382, 388 & 390

Formation, geology and oceanography

The Topgallant Islands were formed about 8750 years ago following the rise of sea levels at the start of the

Holocene The Holocene () is the current geologic time scale, geological epoch, beginning approximately 11,700 years ago. It follows the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene to ...

. Geologically, the constituent parts of the Topgallant Islands are the remnants of a stack of

calcarenite Calcarenite is a type of limestone that is composed predominantly, more than 50 percent, of detrital (transported) sand-size (0.0625 to 2 mm in diameter), Carbonate rock, carbonate grains. The grains consist of sand-size grains of either cor ...

strata sitting on a now-submerged ridge of

granite Granite ( ) is a coarse-grained (phanerite, phaneritic) intrusive rock, intrusive igneous rock composed mostly of quartz, alkali feldspar, and plagioclase. It forms from magma with a high content of silica and alkali metal oxides that slowly coo ...

which is now submerged and which has been extensively eroded by wave action since the commencement of sea level rise. The Topgallant Islands are part of a submerged reef system orientated along a north north-west axis which extends from the islet in the west to the east of the southernmost rock for a distance of about with ‘sunken rocks’ extending about to the south west of the islet. A depth of is reached within to the west.

Flora and fauna

Flora

Vegetation is restricted generally to the summit of the islet where the soil is sufficiently deep to permit the growth of shrubs and two of the larger rocks. A survey conducted in 1980 found ‘four distinct plant communities’ to present as ‘low

shrubland Shrubland, scrubland, scrub, brush, or bush is a plant community characterized by vegetation dominance (ecology), dominated by shrubs, often also including grasses, herbaceous plant, herbs, and geophytes. Shrubland may either occur naturally o ...

s’ dominated by

chenopod Amaranthaceae ( ) is a family of flowering plants commonly known as the amaranth family, in reference to its type genus ''Amaranthus''. It includes the former goosefoot family Chenopodiaceae and contains about 165 genera and 2,040 species, making ...

s (in two instances), nitre bush and pointed twinleaf. Twenty species were recorded during the 1980 survey including the invasive species

African boxthorn ''Lycium ferocissimum'', the African boxthorn or boxthorn, is a shrub in the nightshade family (Solanaceae) indigenous to South Africa. Distribution The species is native to the Western Cape and Eastern Cape provinces in South Africa, where it ...

and common iceplant.

Fauna

Vertebrate Vertebrates () are animals with a vertebral column (backbone or spine), and a cranium, or skull. The vertebral column surrounds and protects the spinal cord, while the cranium protects the brain. The vertebrates make up the subphylum Vertebra ...

animals observed on the island group include

marbled gecko ''Christinus'' is a genus of Gekkonidae geckos found in southern regions of Australia. It contains species and subspecies that are regionally termed as marbled geckos. The contrasted patterns of these geckos, marbling, are found in a variety of ...

s and the following

bird Birds are a group of warm-blooded vertebrates constituting the class (biology), class Aves (), characterised by feathers, toothless beaked jaws, the Oviparity, laying of Eggshell, hard-shelled eggs, a high Metabolism, metabolic rate, a fou ...

species:

Richard's pipit Richard's pipit (''Anthus richardi'') is a medium-sized passerine bird which breeds in open grasslands in the East Palearctic. It is a long-distance bird migration, migrant moving to open lowlands in the Indian subcontinent and Southeast Asia. It ...

white-faced heron The white-faced heron (''Egretta novaehollandiae'') also known as the white-fronted heron, and incorrectly as the grey heron, or blue crane, is a common bird throughout most of Australasia, including New Guinea, the islands of Torres Strait, Indo ...

Nankeen kestrel The nankeen kestrel (''Falco cenchroides''), also known as the Australian kestrel, is a raptor native to Australia and New Guinea. It is one of the smallest falcons, and unlike many, does not rely on speed to catch its prey. Instead, it simply pe ...

white-bellied sea-eagle The white-bellied sea eagle (''Icthyophaga leucogaster''), also known as the white-breasted sea eagle, is a large diurnal bird of prey in the family Accipitridae. Originally described by Johann Friedrich Gmelin in 1788, it is closely related ...

welcome swallow The welcome swallow (''Hirundo neoxena'') is a small passerine bird in the swallow family Hirundinidae that is native to Australia and Melanesia, nearby islands. It has self-introduced into New Zealand in the middle of the twentieth century. It ...

silver gull The silver gull (''Chroicocephalus novaehollandiae'') is a gull in Oceania. It is the most common gull of Australia. It has been found throughout the continent, but particularly at or near coastal areas. It is smaller than the Pacific gull (''L ...

rock parrot The rock parrot (''Neophema petrophila'') is a species of Neophema, grass parrot native to Australia. Described by John Gould in 1841, it is a small parrot long and weighing with predominantly olive (color), olive-brown upperparts and more yell ...

white-faced storm petrel The white-faced storm petrel (''Pelagodroma marina''), (Māori language, Māori: ''takahikare'') also known as white-faced petrel or frigate petrel is a small seabird of the austral storm petrel family Oceanitidae. It is the only member of the m ...

short-tailed shearwater The short-tailed shearwater or slender-billed shearwater (''Ardenna tenuirostris''; formerly ''Puffinus tenuirostris''), also called yolla or moonbird, and commonly known as the muttonbird in Australia, is the most abundant seabird species in A ...

and

common starling The common starling (''Sturnus vulgaris''), also known simply as the starling in Great Britain and Ireland, and as European starling in North America, is a medium-sized passerine bird in the starling family, Sturnidae. It is about long and ha ...

History

European discovery and use

Flinders discovered the island group on Saturday, 13 February 1802, and named it due to it ‘resembling ships under sail’. On the same day, Flinders also nominated it as one of the constituent parts of the Investigator Group.Flinders, 1814 (1966), pages 221

Protected areas status

The Topgallant Islands first received

status as part of a fauna reserve declared under the ''Fauna Conservation Act 1964'' either on 1 September 1966 or 16 March 1967. The island group and other adjoining islands became part of the

Investigator Group Conservation Park . __NOTOC__ Investigator Group Conservation Park was a protected area in the Australian state of South Australia located on islands within the Investigator Group of islands off the west coast of Eyre Peninsula about north-west of the state cap ...

proclaimed under the ''National Parks and Wildlife Act 1972'' in 1972. On 25 August 2011, it was one of the island groups excised from the Investigator Group Conservation Park to form the Investigator Group Wilderness Protection Area. Since 2012, the waters adjoining the Topgallant Islands have been part of a sanctuary zone in the

Investigator Marine Park __NOTOC__ Investigator Marine Park is a marine protected area in the Australian state of South Australia located in the state's coastal waters in its west adjoining the west coast of Eyre Peninsula and islands in the Investigator Group respective ...

.DEH, 2006, pages 5-6WAC, 2013, pages 16-17DEWNR, 2012, page 26 of 26

Citations and references

Citations

References

* * * * * * {{DEFAULTSORT:Topgallant Islands Islands of South Australia Uninhabited islands of Australia Great Australian Bight