The San Matias Gulf is an inlet of the

Atlantic Ocean The Atlantic Ocean is the second largest of the world's five borders of the oceans, oceanic divisions, with an area of about . It covers approximately 17% of Earth#Surface, Earth's surface and about 24% of its water surface area. During the ...

off the coast of

Patagonia Patagonia () is a geographical region that includes parts of Argentina and Chile at the southern end of South America. The region includes the southern section of the Andes mountain chain with lakes, fjords, temperate rainforests, and glaciers ...

Argentina Argentina, officially the Argentine Republic, is a country in the southern half of South America. It covers an area of , making it the List of South American countries by area, second-largest country in South America after Brazil, the fourt ...

. It is bordered by the

Río Negro Province Río Negro (, ''Black River'') is a province of Argentina, located in northern Patagonia. Neighboring provinces are from the south clockwise Chubut, Neuquén, Mendoza, La Pampa and Buenos Aires. To the east lies the Atlantic Ocean. Its cap ...

to the north and west, and the

Valdes Peninsula Valdez or Valdés may refer to: People *Valdez (surname) *Valdés (surname) * Valdez (Brazilian footballer) (born 1943), a Brazilian former footballer * Valdez Demings, U.S. politician Geography * Valdés, Asturias, Spain *Valdez, Alaska Vald ...

of the

Chubut Province Chubut ( from Tehuelche language, Tehuelche 'transparent'; ) is a provinces of Argentina, province in southern Argentina, situated between the 42nd parallel south (the border with Río Negro Province), the 46th parallel south (bordering Santa ...

to the south. It is "one of the largest gulfs in the Patagonia region". The gulf is surrounded by plateaus and depressions below sea level similar to the gulf itself but that are not flooded by the sea at present. The gulf was the subject of scientific investigation for its unusually large

sand waves A sand wave is frequently defined as a type of usually a large, ridge-like bathymetric feature, called a '' bedform'', that is created by the interaction between underwater unidirectional currents with noncohesive, granular sediment, e.g., silt, ...

and their movement. The local fishing industry may be unsustainably harvesting the purple clam ('' Amiantis purpurata''), the Tehuelche scallop ('' Aequipecten tehuelchus''), the blue mussel (''

Mytilus edulis The blue mussel (''Mytilus edulis''), also known as the common mussel, is a medium-sized edible marine (ocean), marine bivalve mollusc in the family (biology), family Mytilidae, the only extant family in the order (biology), order Mytilida, known ...

''), and the ribbed mussel ('' Aulacomya atra''), as well as the Patagonian octopus ('' Octopus tehuelchus''). The 2003 commercial

squid A squid (: squid) is a mollusc with an elongated soft body, large eyes, eight cephalopod limb, arms, and two tentacles in the orders Myopsida, Oegopsida, and Bathyteuthida (though many other molluscs within the broader Neocoleoidea are also ...

harvest broke the previous record set in 2001 by more than double at . As of 2014, this gulf is the only location in the world where swimming with whales is permitted for tourism, with

right whale Right whales are three species of large baleen whales of the genus ''Eubalaena'': the North Atlantic right whale (''E. glacialis''), the North Pacific right whale (''E. japonica'') and the southern right whale (''E. australis''). They are class ...

s. The San Matías Gulf has a history of tectonic origin. Prior to the

deglaciation Deglaciation is the transition from full glacial conditions during ice ages, to warm interglacials, characterized by global warming and sea level rise due to change in continental ice volume. Thus, it refers to the retreat of a glacier, an ice shee ...

that followed the last glacial period San Matías Gulf was a dry flatland below

sea level Mean sea level (MSL, often shortened to sea level) is an mean, average surface level of one or more among Earth's coastal Body of water, bodies of water from which heights such as elevation may be measured. The global MSL is a type of vertical ...

. As global deglaciation went on after the

Last Glacial Maximum The Last Glacial Maximum (LGM), also referred to as the Last Glacial Coldest Period, was the most recent time during the Last Glacial Period where ice sheets were at their greatest extent between 26,000 and 20,000 years ago. Ice sheets covered m ...

sea level rose so that 11,000 years before present sea level surpassed the San Matías sill flooding the whole basin. This sill is currently 60 meters below sea level. The gulf has been repeatedly dried up and flooded during

Quaternary The Quaternary ( ) is the current and most recent of the three periods of the Cenozoic Era in the geologic time scale of the International Commission on Stratigraphy (ICS), as well as the current and most recent of the twelve periods of the ...

glacial A glacier (; or ) is a persistent body of dense ice, a form of rock, that is constantly moving downhill under its own weight. A glacier forms where the accumulation of snow exceeds its ablation over many years, often centuries. It acquires ...

and

interglacial An interglacial period (or alternatively interglacial, interglaciation) is a geological interval of warmer global average temperature lasting thousands of years that separates consecutive glacial periods within an ice age. The current Holocene i ...

periods respectively.

References

Gulfs of Argentina {{marine-geo-stub