The Isthmus of Panama (Spanish: Istmo de Panamá), also historically known as the Isthmus of
Darien (Istmo de Darién), 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 isthmus formed around 2.8 million years ago.
This major geological event separated the Atlantic and Pacific Oceans and caused the
creation of the Gulf Stream.
This was first suggested in 1910 by North American paleontologist Henry Fairfield Osborn.
He based the proposal on the fossil record of mammals in Central America.
This conclusion provided a foundation for Alfred Wegener when he proposed the theory
of continental drift in 1912.
== History ==
Vasco Núñez de Balboa heard of the South Sea from natives while sailing along the Caribbean
coast.
On 25 September 1513 he saw the Pacific.
In 1519 the town of Panamá was founded near a small indigenous settlement on the Pacific
coast.
After the discovery of Peru, it developed into an important port of trade and became
an administrative centre.
In 1671 the Welsh pirate Henry Morgan crossed the Isthmus of Panamá from the Caribbean
side and destroyed the city.
The town was relocated some kilometers to the west at a small peninsula.
The ruins of the old town, Panamá Viejo, are preserved and were declared a UNESCO World
Heritage Site in 1997.
Silver and gold from the viceroyalty of Peru were transported overland across the isthmus
by Spanish Silver Train to Porto Bello, where Spanish treasure fleets shipped them to Seville
and Cádiz from 1707.
Lionel Wafer spent four years between 1680 and 1684 among the Cuna Indians.
Scotland tried to establish a settlement in 1698 through the Darien scheme.
The California Gold Rush, starting in 1849, brought a large increase in the transportation
of people from the Atlantic to the Pacific.
Steamships brought gold diggers from eastern US ports, who trekked across the isthmus by
foot, horse, and later rail.
On the Pacific side, they boarded Pacific Mail Steamship Company vessels headed for
San Francisco.
Ferdinand de Lesseps, the man behind the Suez Canal, started a Panama Canal Company in 1880
that went bankrupt in 1889 in the Panama scandals.
In 1902–4, the United States forced Colombia to grant independence to the Department of
the Isthmus, bought the remaining assets of the Panama Canal Company, and finished the
canal in 1914.
== Geology ==
A significant body of water (referred to as the Central American Seaway) once separated
the continents of North and South America, allowing the waters of the Pacific and Atlantic
Oceans to mix freely.
Beneath the surface, two plates of the Earth's crust were slowly colliding, forcing the Cocos
Plate to slide under the Caribbean Plate.
The pressure and heat caused by this collision led to the formation of underwater volcanoes,
some of which grew large enough to form islands as early as 15 million years ago.
Meanwhile, movement of the two tectonic plates was also pushing up the sea floor, eventually
forcing some areas above sea level.
Over time, massive amounts of sediment (sand, soil, and mud) from North and South America
filled the gaps between the newly forming islands.
Over millions of years, the sediment deposits added to the islands until the gaps were completely
filled.
By no later than 4.5 million years ago, an isthmus had formed between North and South
America.
However, an article in Science Magazine stated that zircon crystals in middle Miocene bedrock
from northern Colombia indicated that by 10 million years ago, it is likely that instead
of islands, a full isthmus between the North and South American continents had already
likely formed where the Central American Seaway had been previously.Evidence also suggests
that the creation of this land mass and the subsequent warm, wet weather over northern
Europe resulted in the formation of a large Arctic ice cap and contributed to the current
ice age.
That warm currents can lead to glacier formation may seem counterintuitive, but heated air
flowing over the warm Gulf Stream can hold more moisture.
The result is increased precipitation that contributes to snow pack.The formation of
the Isthmus of Panama also played a major role in biodiversity on the planet.
The bridge made it easier for animals and plants to migrate between the two continents.
This event is known in paleontology as the Great American Interchange.
For instance, in North America today, the opossum, armadillo, and porcupine all trace
back to ancestors that came across the land bridge from South America.
Likewise, bears, cats, dogs, horses, llamas, and raccoons all made the trek south across
the isthmus.
== Biosphere == As the connecting bridge between two vast
land masses, the Panamanian biosphere is filled with overlapping fauna and flora from both
North and South America.
There are, for example, over 978 species of birds in the isthmus area.
The tropical climate also encourages a myriad of large and brightly colored species, insects,
amphibians, birds, fish, and reptiles.
Divided along its length by a mountain range, the isthmus's weather is generally wet on
the Atlantic (Caribbean) side but has a clearer division into wet and dry seasons on the Pacific
side.
== See also == Darien Gap
Isthmo-Colombian area Postage stamps and postal history of the Canal
Zone
== References ==
=== Notes ===
=== Sources ===