Topgallant Islands is an island group in the Australian state of

South Australia South Australia (commonly abbreviated as SA) is a state in the southern central part of Australia. It covers some of the most arid parts of the country. With a total land area of , it is the fourth-largest of Australia's states and territories ...

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 explore ...

about south west of

Cape Finniss Cape Finniss (also spelt Cape Finnis) is a headland located at the southern extremity of Anxious Bay on the west coast of Eyre Peninsula in South Australia about Points of the compass#32 cardinal points, Northwest by west of the town of Elliston ...

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. Originally called Eyre’s Peninsula, it was named aft ...

. The group was discovered and named by

Matthew Flinders Captain Matthew Flinders (16 March 1774 – 19 July 1814) was a British navigator and cartographer who led the first inshore circumnavigation of mainland Australia, then called New Holland. He is also credited as being the first person to u ...

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, ecological or cultural values. There are several kinds of protected areas, which vary by level of protection depending on the ena ...

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 ...

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 The points of the compass are a set of horizontal, Radius, radially arrayed compass directions (or Azimuth#In navigation, azimuths) used in navigation and cartography. A compass rose is primarily composed of four cardinal directions—north, east ...

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. Flinders Island was the place where the last remnants of aboriginal Tasmanian population were exiled by the colo ...

.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 and thrust are supplied by horizontally spinning rotors. This allows the helicopter to take off and land vertically, to hover, and to fly forward, backward and laterally. These attributes ...

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 geological epoch. It began approximately 11,650 cal years Before Present (), after the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene togethe ...

. 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 grains. The grains consist of sand-size grains of either corals, shells, ooi ...

strata sitting on a now-submerged ridge of

granite Granite () is a coarse-grained (phaneritic) 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 cools and solidifies undergro ...

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 dominated by shrubs, often also including grasses, herbs, and geophytes. Shrubland may either occur naturally or be the result of human activity. It m ...

s’ dominated by chenopods (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). The species is native to the Western Cape, Eastern Cape, and Free State provinces in South Africa and has become naturalised in Aus ...

and common iceplant.

Fauna

Vertebrate Vertebrates () comprise all animal taxa within the subphylum Vertebrata () ( chordates with backbones), including all mammals, birds, reptiles, amphibians, and fish. Vertebrates represent the overwhelming majority of the phylum Chordata, ...

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 Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweigh ...

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 migrant moving to open lowlands in the Indian subcontinent and Southeast Asia. It is a rare but ...

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, Ind ...

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 (''Haliaeetus 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 t ...

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

silver gull The silver gull (''Chroicocephalus novaehollandiae'') 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 (''Larus pacificus''), which ...

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

white-faced storm petrel The white-faced storm petrel (''Pelagodroma marina''), also known as white-faced petrel is a small seabird of the austral storm petrel family Oceanitidae. It is the only member of the monotypic genus ''Pelagodroma''. Description The white-faced ...

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 or European starling (''Sturnus vulgaris''), also known simply as the starling in Great Britain and Ireland, is a medium-sized passerine bird in the starling family, Sturnidae. It is about long and has glossy black plumage ...

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 ca ...

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