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__NOTOC__ Margaret Brock Reef is a reef 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 state's coastal waters on its south-east coast about west of the headland of
Cape Jaffa Cape Jaffa is a headland in the Australian state of South Australia located at the south end of Lacepede Bay on the state's south east coast about south west of the town centre of Kingston SE. The cape is described as being "a low sandy point" ...
and about south-west of the town of
Kingston SE Kingston SE (Kingston South East to distinguish it from Kingston-on-Murray) formerly Kingston is a town in the Australian state of South Australia located in the state's south-east coastline on the shores of Lacepede Bay. It is located about ...
. It is the site of both a
navigation aid Navigation is a field of study that focuses on the process of monitoring and controlling the movement of a craft or vehicle from one place to another.Bowditch, 2003:799. The field of navigation includes four general categories: land navigation, ...
which operated as a staffed lighthouse from 1872 to 1973 and as an automatic beacon onward to the present day, and a rock lobster sanctuary declared under state law in 1973. It is named after the barque '' Margaret Brock'' which was wrecked there in 1852.


Description

Margaret Brock Reef is located about west of the headland of Cape Jaffa and about southwest of the town of Kingston SE. The reef stands above a seabed located above the depth contour and parts of it are above sea-level at low tide. The portion of the reef which is shown on a chart published in one source as being shallower than depth extends for about in a north–south direction with the northern end being located about north of the former lighthouse platform. At low tide, the highest part of the reef can dry to a height of above sea-level.


Formation, geology and oceanography

Margaret Brock Reef was formed about 6000 to 7000 years ago by rising sea level. The reef and two islands to its south,
Baudin Rocks Baudin Rocks, also previously known as the Godfrey Islands, is a group of islets on the south east coast of in the Australian state of South Australia about North-northwest of Robe. The islet group was discovered and named by Matthew Flinder ...
and Penguin Island, are remnants of a former dune system known as the Robe Range which extended from what is now Cape Jaffa to what is now Cape Banks in the south. The range is composed of a "crumbly rock" known as Bridgewater Formation calcarenite which is described in some sources as being
aeolianite Eolianite or aeolianite is any rock formed by the lithification of sediment deposited by aeolian processes; that is, the wind. In common use, however, the term refers specifically to the most common form of eolianite: coastal limestone consisting ...
. One source describes the reef as being "an extensive danger" because of the presence of water depths less than , and because a vessel's crew may not see the reef's edge as waves may not break there and as the sea for a distance up to to the reef's west will form waves in stormy weather that break.


History


European discovery

Margaret Brock Reef was seen by the Baudin expedition in April 1802. In 1826, ''
Sesostris Sesostris ( grc-gre, Σέσωστρις), also transliterated as Sesoösis, or Sesonchosis, is the name of a legendary king of ancient Egypt who, according to Herodotus, led a military expedition into parts of Europe. Tales of Sesostris are pro ...
'', a ship carrying convicts to the colony of New South Wales and under the command of a Captain Drake sighted the reef on the way to Sydney. The barque ''Margaret Brock'' was wrecked on the reef on 23 November 1852. A chart prepared by
Thomas Lipson Captain Thomas Lipson (ca.1784 – 25 October 1863) was an officer in the Royal Navy, who, after a successful if unspectacular career in the Royal Navy, was appointed by the Admiralty as the first Harbourmaster, Harbour Master at South Australia, ...
, the South Australian Government harbor master, showing the location of the reefs to the west of Cape Jaffa including Margaret Brock Reef as well as the location of the wreck of ''Margaret Brock'' was published in
The South Australian Government Gazette ''The South Australian Government Gazette'' is the government gazette of the South Australian Government. The ''South Australian Gazette'' was first printed on 20 June 1839, after the South Australian Government The Government of South Aus ...
on 7 April 1853.


Naming

The name "Sesostris Reef" was used for the reef from 1826 onwards to at least the late 1870s. In particular, it was used in one publication, ''The Australian Directory'', until 1878, but was replaced by the name "Margaret Brock Reef" in the 1879 edition. The name "Margaret Brock Reef" was in use in South Australia by 1865.


Shipwrecks

Ships wrecked on the reef include the brigantine ''
Maria Maria may refer to: People * Mary, mother of Jesus * Maria (given name), a popular given name in many languages Place names Extraterrestrial *170 Maria, a Main belt S-type asteroid discovered in 1877 *Lunar maria (plural of ''mare''), large, da ...
'' in 1840, the barque ''Margaret Brock'' in 1852, the schooner ''Agnes'' in 1865, the fishing vessel ''Thunderbird'' in 1964 and the fishing vessel ''Explorer'' in 1977.


Navigation aids

The Cape Jaffa Lighthouse, also called the Margaret Brock Reef lighthouse in some sources, was built on part of the reef which is dry at low tide. Construction commenced in 1868 and the light was first used in January 1872. In 1973, its role was degraded after the commissioning of a new lighthouse at
Robe A robe is a loose-fitting outer garment. Unlike garments described as capes or cloaks, robes usually have sleeves. The English word ''robe'' derives from Middle English ''robe'' ("garment"), borrowed from Old French ''robe'' ("booty, spoils" ...
. In 1975, the portion of the structure consisting of the lantern room and the keepers' accommodation was dismantled and re-erected in Kingston SE for use by the
National Trust of South Australia The National Trust of Australia, officially the Australian Council of National Trusts (ACNT), is the Australian national peak body for community-based, non-government non-profit organisations committed to promoting and conserving Australia's Ind ...
as a museum. The platform remaining on the reef now accommodates an automatic beacon and is known as the Margaret Brock Reef Light.


Protected area status and other designations

Margaret Brock Reef is the site of a sanctuary where fishing for
southern rock lobster ''Jasus edwardsii'', the southern rock lobster, red rock lobster, or spiny rock lobster, is a species of spiny lobster found throughout coastal waters of southern Australia and New Zealand including the Chatham Islands. It is commonly called '' ...
is prohibited at all times. It was originally proclaimed in 1973 to amend an earlier statute, the state's ''Fisheries Act 1971'', and subsequently was re-proclaimed under the state's ''Fisheries Management Act 2007''. The sanctuary occupies the area within a radius of of the navigation aid located on the former lighthouse platform. The rock lobster sanctuary was listed as a
marine protected area Marine protected areas (MPA) are protected areas of seas, oceans, estuaries or in the US, the Great Lakes. These marine areas can come in many forms ranging from wildlife refuges to research facilities. MPAs restrict human activity for a conserv ...
from 2008 to 2014 on the Australian government's Collaborative Australian Protected Area Database (CAPAD).


References

{{Limestone Coast, state=collapsed Limestone Coast Reefs of Australia