The Central American Seaway, also known as the PanamanicInter-American and Proto-Caribbean Seaway, was a body of water that once separated North America from South America. It formed in the Mesozoic (200–154 Ma) during the breakup of the supercontinent Pangaea, and closed when the Isthmus of Panama was formed by volcanic activity in the late Pliocene (2.76–2.54 Ma).
The closure of the Central American Seaway had tremendous effects on oceanic circulation and the biogeography of the adjacent seas, isolating many species and triggering speciation and diversification of tropical and sub-tropical marine fauna.The inflow of nutrient-rich water of deep Pacific origin into the Caribbean was blocked, so local species had to adapt to an environment of lower productivity. It had an even larger impact on terrestrial life. The seaway had isolated South America for much of the Cenozoic, allowing the evolution of a wholly unique diverse mammalian fauna there; when it closed, a faunal exchange with North America ensued, leading to the extinction of many of the native South American forms.
The evidence for when the Central American landmass emerged and the closing of the Central American Seaway can be divided into three categories. The first is the direct geologic observation of crustal thickening and submarine deposits in Central America. The second is the Great American Interchange of vertebrates between North and South America which required a continuous land bridge across the two areas for the organisms to travel along with a climate that was very different from the climate today. Lastly is the development of differences in marine assemblages and their isotopic signatures in the Caribbean from those in the Pacific.The Central American Seaway was closed by the elevation of the Central American Isthmus which is proposed to have occurred three and a half to five million years ago. The closing of the Central American Seaway is also supported by the evolution of taxa on different sides of the Central American Isthmus along with the different histories of the oceans on either side of the isthmus.
The closing of the seaway allowed a major migration of land mammals between North and South America, known as the Great American Interchange. This allowed species of mammals such as cats, canids, horses, elephants and camels to migrate from North America to South America, while porcupines, ground sloths, glyptodonts and terror birds made the reverse migration. There is much controversy about glacial and interglacial climates in South America. Research shows that vegetation in most of the Amazon basin has changed very little since glacial times, although it is believed there was more savanna present during that period. A closed seaway would have led to a very different North Atlantic Ocean circulation, impacting the surrounding atmospheric temperatures, which in turn affected the glacial cycle. The emergence of the isthmus caused a reflection of the westward-flowing North Equatorial Current northward and enhanced the northward-flowing Gulf Stream.The Pacific coast of South America would have cooled as the input of warm water from the Caribbean was cut off. This trend is thought to have caused the extinction of the marine sloths of the area.
The closure of the seaway led to an increased poleward salt and heat transport, strengthening the North Atlantic thermohaline circulation 2.95–2.82 million years ago, in turn increasing moisture supply to Arctic latitudes, contributing to both Arctic continental glaciation and sea ice formation, and eventually—with the orbitally paced extension of Gelasian ice sheets—the Quaternary ice age.
The Atlantic Ocean is the second largest of the world's oceans, with an area of about 106,460,000 square kilometers. It covers approximately 20 percent of Earth's surface and about 29 percent of its water surface area. It separates the "Old World" from the "New World".
The Antarctic Circumpolar Current (ACC) is an ocean current that flows clockwise from west to east around Antarctica. An alternative name for the ACC is the West Wind Drift. The ACC is the dominant circulation feature of the Southern Ocean and has a mean transport estimated at 100-150 Sverdrups, or possibly even higher, making it the largest ocean current. The current is circumpolar due to the lack of any landmass connecting with Antarctica and this keeps warm ocean waters away from Antarctica, enabling that continent to maintain its huge ice sheet.
The Caribbean Sea is an American Mediterranean Sea of the Atlantic Ocean in the tropics of the Western Hemisphere. It is bounded by Mexico and Central America to the west and south west, to the north by the Greater Antilles starting with Cuba, to the east by the Lesser Antilles, and to the south by the north coast of South America.
North Atlantic Deep Water (NADW) is a deep water mass formed in the North Atlantic Ocean. Thermohaline circulation of the world's oceans involves the flow of warm surface waters from the southern hemisphere into the North Atlantic. Water flowing northward becomes modified through evaporation and mixing with other water masses, leading to increased salinity. When this water reaches the North Atlantic it cools and sinks through convection, due to its decreased temperature and increased salinity resulting in increased density. NADW is the outflow of this thick deep layer, which can be detected by its high salinity, high oxygen content, nutrient minima, high 14C/12C, and chlorofluorocarbons (CFCs).
The Oligocene is a geologic epoch of the Paleogene Period and extends from about 33.9 million to 23 million years before the present. As with other older geologic periods, the rock beds that define the epoch are well identified but the exact dates of the start and end of the epoch are slightly uncertain. The name Oligocene was coined in 1854 by the German paleontologist Heinrich Ernst Beyrich; the name comes from the Ancient Greek ὀλίγος and καινός, and refers to the sparsity of extant forms of molluscs. The Oligocene is preceded by the Eocene Epoch and is followed by the Miocene Epoch. The Oligocene is the third and final epoch of the Paleogene Period.
The Weddell Sea is part of the Southern Ocean and contains the Weddell Gyre. Its land boundaries are defined by the bay formed from the coasts of Coats Land and the Antarctic Peninsula. The easternmost point is Cape Norvegia at Princess Martha Coast, Queen Maud Land. To the east of Cape Norvegia is the King Haakon VII Sea. Much of the southern part of the sea is covered by a permanent, massive ice shelf field, the Filchner-Ronne Ice Shelf.
An ocean current is a continuous, directed movement of sea water generated by a number of forces acting upon the water, including wind, the Coriolis effect, breaking waves, cabbeling, and temperature and salinity differences. Depth contours, shoreline configurations, and interactions with other currents influence a current's direction and strength. Ocean currents are primarily horizontal water movements.
Thermohaline circulation (THC) is a part of the large-scale ocean circulation that is driven by global density gradients created by surface heat and freshwater fluxes. The adjective thermohaline derives from thermo- referring to temperature and -haline referring to salt content, factors which together determine the density of sea water. Wind-driven surface currents travel polewards from the equatorial Atlantic Ocean, cooling en route, and eventually sinking at high latitudes. This dense water then flows into the ocean basins. While the bulk of it upwells in the Southern Ocean, the oldest waters upwell in the North Pacific. Extensive mixing therefore takes place between the ocean basins, reducing differences between them and making the Earth's oceans a global system. The water in these circuits transport both energy and mass around the globe. As such, the state of the circulation has a large impact on the climate of the Earth.
The Isthmus of Panama, also historically known as the Isthmus of Darien, is the narrow strip of land that lies between the Caribbean Sea and the Pacific Ocean, linking North and South America. It contains the country of Panama and the Panama Canal. Like many isthmuses, it is a location of great strategic value.
The Caribbean Plate is a mostly oceanic tectonic plate underlying Central America and the Caribbean Sea off the north coast of South America.
The Great American Biotic Interchange, also known as the Great American Interchange or Great American Faunal Interchange, was an important late Cenozoic paleozoogeographic event in which land and freshwater fauna migrated from North America via Central America to South America and vice versa, as the volcanic Isthmus of Panama rose up from the sea floor and bridged the formerly separated continents. Although earlier dispersals have occurred, probably over water, the migration accelerated dramatically about 2.7 million years (Ma) ago during the Piacenzian age. It resulted in the joining of the Neotropic and Nearctic biogeographic realms definitively to form the Americas. The interchange is visible from observation of both biostratigraphy and nature (neontology). Its most dramatic effect is on the zoogeography of mammals, but it also gave an opportunity for reptiles, amphibians, arthropods, weak-flying or flightless birds, and even freshwater fish to migrate.
A shutdown or slowdown of the thermohaline circulation is a hypothesized effect of global warming on a major ocean circulation.
The Atlantic meridional overturning circulation (AMOC) is the zonally-integrated component of surface and deep currents in the Atlantic Ocean. It is characterized by a northward flow of warm, salty water in the upper layers of the Atlantic, and a southward flow of colder, deep waters that are part of the thermohaline circulation. These "limbs" are linked by regions of overturning in the Nordic and Labrador Seas and the Southern Ocean. The AMOC is an important component of the Earth's climate system, and is a result of both atmospheric and thermohaline drivers.
Sloths are a group of arboreal neotropical xenathran mammals, constituting the suborder Folivora. Noted for slowness of movement, they spend most of their lives hanging upside down in the trees of the tropical rain forests of South America and Central America. They are considered to be most closely related to anteaters, together making up the xenarthran order Pilosa. There are six extant sloth species in two genera – Bradypus and Choloepus. Despite this traditional naming, all sloths actually have three toes on each rear limb, although two-toed sloths have only two digits on each forelimb. The two groups of sloths are from different, distantly related families, and are thought to have evolved their morphology via parallel evolution from terrestrial ancestors. Besides the extant species, many species of ground sloth ranging up to the size of elephants like Megatherium inhabited both North and South America during the Pleistocene epoch. However, they became extinct during the Quaternary extinction event around 12,000 years ago, together with most large bodied animals in the New World. The extinction correlates in time with the arrival of humans, but climate change has also been suggested to have contributed. Members of an endemic radiation of Caribbean sloths formerly lived in the Greater Antilles. They included both ground and arboreal forms which became extinct after humans settled the archipelago in the mid-Holocene, around 6,000 years ago.
North America is the third largest continent, and is also a portion of the second largest supercontinent if North and South America are combined into the Americas and Africa, Europe, and Asia are considered to be part of one supercontinent called Afro-Eurasia.
The Panama Plate is a microplate; a small tectonic plate that exists between two actively spreading ridges and moves relatively independently of its surrounding plates. The Panama plate is located between the Cocos Plate and Nazca Plate to the south and the Caribbean Plate to the north. Most of its borders are convergent boundaries including a subduction zone to the west. It consists, for the most part, of the nations of Panama and Costa Rica.
The Gulf Stream, together with its northern extension the North Atlantic Drift, is a warm and swift Atlantic ocean current that originates in the Gulf of Mexico and stretches to the tip of Florida, and follows the eastern coastlines of the United States and Newfoundland before crossing the Atlantic Ocean as the North Atlantic Current. The process of western intensification causes the Gulf Stream to be a northwards accelerating current off the east coast of North America. At about, it splits in two, with the northern stream, the North Atlantic Drift, crossing to Northern Europe and the southern stream, the Canary Current, recirculating off West Africa.
During the Pliocene epoch climate became cooler and drier, and seasonal, similar to modern climates.
The phenomenon of paleoflooding is apparent in the geologic record over various spatial and temporal scales. It often occurred on a large scale, and was the result of either glacial ice melt causing large outbursts of freshwater, or high sea levels breaching bodies of freshwater. If a freshwater outflow event was large enough that the water reached the ocean system, it caused changes in salinity that potentially affected ocean circulation and global climate. Freshwater flows could also accumulate to form continental glacial lakes, and this is another indicator of large-scale flooding. In contrast, periods of high global sea level could cause marine water to breach natural dams and flow into bodies of freshwater. Changes in salinity of freshwater and marine bodies can be detected from the analysis of organisms that inhabited those bodies at a given time, as certain organisms are more suited to live in either fresh or saline conditions.
The geology of Panama includes the complex tectonic interplay between the Pacific, Cocos and Nazca plates, the Caribbean Plate and the Panama Microplate.