The
Sahul Shelf is part of the
continental shelfThe continental shelf is the extended perimeter of each continent and associated coastal plain, and was part of the continent during the glacial periods, but is undersea during interglacial periods such as the current epoch by relatively shallow seas and gulfs. The continental rise is below the...
of
SahulAustralia is the smallest of the geographic continents, though not of geological continents. There is no universally accepted definition of the word "continent"; the lay definition is "One of the main continuous bodies of land on the earth's surface."...
(the Australia-New Guinea continent) and lies off the northern coast of
AustraliaAustralia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the continental mainland , the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans...
. The Sahul Shelf proper stretches northwest from Australia much of the way under the
Timor SeaThe Timor Sea is a sea bounded to the north by the island of Timor, to the east by the Arafura Sea, to the south by Australia and to the west by the Indian Ocean.- Geography :...
towards
TimorTimor is an island at the southern end of Maritime Southeast Asia, north of the Timor Sea. It is divided between the independent state of East Timor, and West Timor, belonging to the Indonesian province of East Nusa Tenggara....
, ending where the seabed begins descending into the
Timor TroughThe Timor Trough is a oceanic trough that is a continuation of the Sunda Trench that marks the boundary between Indo-Australian Plate's continental shelf and the Timor Plate to the north...
. Another part of the Sahul Shelf is known also as the Arafura Shelf and runs all the way from the northern coast of Australia under the
Arafura SeaThe Arafura Sea lies west of the Pacific Ocean overlying the continental shelf between Australia and New Guinea. It is bordered by Torres Strait and through that the Coral Sea to the east, the Gulf of Carpentaria to the south, the Timor Sea to the west and the Banda and Ceram seas to the northwest....
to
New GuineaNew Guinea, located north of Australia, is the world's second largest island. It became separated from the Australian mainland when the area now known as the Torres Strait flooded after the last glacial period. The name Papua has long been associated with the island...
.
The
Sahul Shelf is part of the
continental shelfThe continental shelf is the extended perimeter of each continent and associated coastal plain, and was part of the continent during the glacial periods, but is undersea during interglacial periods such as the current epoch by relatively shallow seas and gulfs. The continental rise is below the...
of
SahulAustralia is the smallest of the geographic continents, though not of geological continents. There is no universally accepted definition of the word "continent"; the lay definition is "One of the main continuous bodies of land on the earth's surface."...
(the Australia-New Guinea continent) and lies off the northern coast of
AustraliaAustralia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the continental mainland , the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans...
. The Sahul Shelf proper stretches northwest from Australia much of the way under the
Timor SeaThe Timor Sea is a sea bounded to the north by the island of Timor, to the east by the Arafura Sea, to the south by Australia and to the west by the Indian Ocean.- Geography :...
towards
TimorTimor is an island at the southern end of Maritime Southeast Asia, north of the Timor Sea. It is divided between the independent state of East Timor, and West Timor, belonging to the Indonesian province of East Nusa Tenggara....
, ending where the seabed begins descending into the
Timor TroughThe Timor Trough is a oceanic trough that is a continuation of the Sunda Trench that marks the boundary between Indo-Australian Plate's continental shelf and the Timor Plate to the north...
. Another part of the Sahul Shelf is known also as the Arafura Shelf and runs all the way from the northern coast of Australia under the
Arafura SeaThe Arafura Sea lies west of the Pacific Ocean overlying the continental shelf between Australia and New Guinea. It is bordered by Torres Strait and through that the Coral Sea to the east, the Gulf of Carpentaria to the south, the Timor Sea to the west and the Banda and Ceram seas to the northwest....
to
New GuineaNew Guinea, located north of Australia, is the world's second largest island. It became separated from the Australian mainland when the area now known as the Torres Strait flooded after the last glacial period. The name Papua has long been associated with the island...
. The
Aru IslandsThe Aru Islands are a group of about ninety-five low-lying islands in the Maluku province of eastern Indonesia.-Geography:...
rise from the Arafura Shelf. The Sahul Shelf is sometimes taken to also include the Rowley Shelf which runs out under the
Indian OceanThe Indian Ocean is the third largest of the world's oceanic divisions, covering about 20% of the water on the Earth's surface. It is bounded on the north by South Asia ; on the west by Africa; on the east by Indochina, the Sunda Islands, and Australia; and on the south by the Southern Ocean...
from the northwest coast of Australia as far south as
North West CapeNorth West Cape is a large peninsula of land in the north west coast of Western Australia. Cape Range runs down the spine of the peninsula and Ningaloo Reef runs along the western edge...
.
When
sea levelMean sea level is the average height of the ocean's surface ; used as a standard in reckoning land elevation.- Measurement :...
s fell during the
PleistoceneThe Pleistocene is the epoch from 2.588 million to 12 000 years BP covering the world's recent period of repeated glaciations. The name pleistocene is derived from the Greek and ....
ice ageThe general term "ice age" or, more precisely, "glacial age" denotes a geological period of long-term reduction in the temperature of the Earth's surface and atmosphere, resulting in an expansion of continental ice sheets, polar ice sheets and alpine glaciers. Within a long-term ice age, individual...
, including the
last glacial maximumThe Last Glacial Maximum refers to the time of maximum extent of the ice sheets during the last glacial period, approximately 20,000 years ago. This extreme persisted for several thousand years. It is followed by the Late Glacial Maximum....
about 18,000 years ago, the Sahul Shelf was exposed as dry land. Evidence of the shoreline of this time has been identified in locations which now lie 100 to 140 metres below sea level. A useful interactive timeline of sea level changes has been developed by Monash University. The Arafura Shelf formed a
land bridgeA land bridge, in biogeography, is an isthmus or wider land connection between otherwise separate areas, which allows terrestrial animals and plants to cross over and colonise new lands...
between Australia, New Guinea and the Aru Islands and these lands share many marsupial mammals, land birds and freshwater fish as a result. Lydekker's Line, a
biogeographicalBiogeography is the study of the distribution of biodiversity over space and time. It aims to reveal where organisms live, and at what abundance....
line, runs along the edge of Sahul Shelf where it drops off into the deep waters of the
WallaceaWallacea is a biogeographical designation for a group of Indonesian islands separated by deep water straits from the Asian and Australian continental shelves. The islands of Wallacea lie between Sundaland to the west, and Near Oceania including Australia and New Guinea to the south and east...
biogeographical area. Wallacea sits in a gap between the Sahul Shelf and the
Sunda ShelfGeologically, the Sunda Shelf is an extension of the continental shelf of Southeast Asia, covered during interglacials by the South China Sea, which isolates as islands Borneo, Sumatra Java and smaller islands. During glacial periods, the sea level falls, and great expanses of the Sunda Shelf are...
, part of the continental shelf of
Southeast AsiaManila
Bangkok
Ho Chi Minh City
Kuala Lumpur
Singapore
Yangon
Bandung
Hanoi
Surabaya
Taichung
Kaohsiung
Medan|-|}...
.
The name "Sahull" or "Sahoel" appeared on 17th century Dutch maps applied to a submerged sandbank between Australia and Timor. On his 1803 map,
Matthew FlindersCaptain Matthew Flinders, RN was one of the most successful navigators and cartographers of his age. In a career that spanned just over twenty years, he sailed with Captain William Bligh, circumnavigated Australia and encouraged the use of that name for the continent...
noted the "Great Sahul Shoal" where
MalayMalays are an ethnic group of Austronesian peoples predominantly inhabiting the Malay Peninsula including the southernmost parts of Thailand, the east coast of Sumatra, the coast of Borneo, and the smaller islands which lie between these locations...
s came from
MakassarMakassar, is the provincial capital of South Sulawesi, Indonesia, and the largest city on Sulawesi Island. From 1971 to 1999, the city was formally named Ujung Pandang, after a precolonial fort in the city, and the two names are often used interchangeably...
to fish for trepang (sea cucumber).
The existence of the much larger Sahul Shelf was suggested in 1845 by G.W. Earl who called it the "Great Australian Bank" and noted that
macropodMacropods are marsupials belonging to the family Macropodidae, which includes kangaroos, wallabies, tree-kangaroos, pademelons, and several others. Before European settlement, there were about 53 species of Macropods. Six species have since become extinct. Another 11 species have been greatly...
s ("kangaroos") were found on Australia, New Guinea and the Aru Islands. Earl also suggested the existence of the Sunda Shelf which he called the "Great Asiatic Bank". The Sahul and Sunda shelves were given their present names by
G.A.F. MolengraaffGustaaf Adolf Frederik Molengraaff was a Dutch geologist, biologist and explorer. He became an authority on the geology of South Africa and the Dutch East Indies....
and W. Weber in 1919.