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Submergent coastlines or drowned coastlines are stretches along the coast that have been inundated by the sea by a relative rise in sea levels from either isostacy or
eustacy Mean sea level (MSL, often shortened to sea level) is an average surface level of one or more among Earth's coastal bodies of water from which heights such as elevation may be measured. The global MSL is a type of vertical datuma standardised g ...
. Submergent coastline are the opposite of emergent coastlines, which have experienced a relative fall in sea levels. Many submergent coastlines were formed by the end of the Last Glacial Period (LGP), when glacial retreat caused both global
sea level rise Globally, sea levels are rising due to human-caused climate change. Between 1901 and 2018, the globally averaged sea level rose by , or 1–2 mm per year on average.IPCC, 2019Summary for Policymakers InIPCC Special Report on the Ocean and Cr ...
and also localised changes to land height. Features of a submergent coastline include
ria A ria (; gl, ría) is a coastal inlet formed by the partial submergence of an unglaciated river valley. It is a drowned river valley that remains open to the sea. Definitions Typically rias have a dendritic, treelike outline although they ca ...
s, which are drowned river valleys and estuaries, and
fjords In physical geography, a fjord or fiord () is a long, narrow inlet with steep sides or cliffs, created by a glacier. Fjords exist on the coasts of Alaska, Antarctica, British Columbia, Chile, Denmark, Germany, Greenland, the Faroe Islands, Icela ...
, which are drowned glaciated valleys. Notable and illustrative examples of submergent coastlines include: * Western
Norway Norway, officially the Kingdom of Norway, is a Nordic countries, Nordic country in Northern Europe, the mainland territory of which comprises the western and northernmost portion of the Scandinavian Peninsula. The remote Arctic island of ...
, famed for its many fjords created by sea level rise at the end of the LGP. * The
Western Coastal Plains The Western Coastal Plains is a strip of coastal plain 50 kilometres (31 mi) in width between the west coast of India and the Western Ghats hills, which starts near the south of the Tapi River. The plains are located between the Western Ghats ...
of the
Indian subcontinent The Indian subcontinent is a physiographical region in Southern Asia. It is situated on the Indian Plate, projecting southwards into the Indian Ocean from the Himalayas. Geopolitically, it includes the countries of Bangladesh, Bhutan, In ...
, which includes the estuaries of the Narmada and the
Tapti The Tapti River (or Tapi) is a river in central India located to the south of the Narmada river that flows westwards before draining into the Arabian Sea. The river has a length of around and flows through the states of Maharashtra, Gujara ...
Rivers. *
Southern England Southern England, or the South of England, also known as the South, is an area of England consisting of its southernmost part, with cultural, economic and political differences from the Midlands and the North. Officially, the area includes ...
and
South Wales South Wales ( cy, De Cymru) is a loosely defined region of Wales bordered by England to the east and mid Wales to the north. Generally considered to include the historic counties of Glamorgan and Monmouthshire, south Wales extends westwards ...
, caused by a "see-saw" reaction to uplift to the north of Great Britain after glacial retreat redistributed weight on the land, including many substantial rias such as
Falmouth Harbour Falmouth Harbour is a horseshoe-shaped bay and natural harbour on the far southern coast of the island of Antigua in Antigua and Barbuda. It is located within Saint Paul Parish. Geography The small township and port of Falmouth lies close t ...
, Plymouth Harbour,
Kingsbridge Estuary The Kingsbridge Estuary (also, erroneously, known as the 'Salcombe Estuary') in the South Hams area of Devon, England runs from Kingsbridge in the north to its mouth at the English Channel near Salcombe and lies between Bolt Head and Sharpitor t ...
and
Milford Haven Milford Haven ( cy, Aberdaugleddau, meaning "mouth of the two Rivers Cleddau") is both a town and a community in Pembrokeshire, Wales. It is situated on the north side of the Milford Haven Waterway, an estuary forming a natural harbour that has ...
. * The
Dalmatia Dalmatia (; hr, Dalmacija ; it, Dalmazia; see names in other languages) is one of the four historical regions of Croatia, alongside Croatia proper, Slavonia, and Istria. Dalmatia is a narrow belt of the east shore of the Adriatic Sea, str ...
n coast, famed for its many small inshore islands, formed by sea level rise in the Mediterranean at the end of the LGP.


References

Coastal and oceanic landforms Coastal geography {{topography-stub