A basin is a depression, or dip, in
the Earth's surface. Basins are
shaped like bowls, with sides
higher than the bottom.
Basins are formed by forces above the
ground (like erosion) or below the
ground (like earthquakes). They can be
created over thousands of years or
The Julian Alps rise above
the crystal-clear waters of
Lake Bohinj in Bohinj,
Slovenia. Like many lake
basins, Lake Bohinj was
carved out as a glacier cut
through the landscape.
development around the
lake help keep the glacial
A split in the Earth's crust
leads into a geyser basin at
Yellowstone National Park,
Wyoming. More than two
thirds of the world's geysers
are located in Yellowstone,
which lies above a huge
collapsed volcano. Most
Yellowstone geyser basins
form in valleys between
ancient lava flows and
Bold bands of sandstone
and darker shale stripe the
Bisti Badlands in New
Mexico's San Juan Basin.
Uranium, oil, gas, and
billions of tons of coal lie
beneath the region, also
known for extensive
dinosaur fossil beds.
Badwater Basin, located
in Death Valley National
Park, California, was
created by flash floods
and excessive heat.
Measured at 86 meters
(282 feet) below sea
level, Badwater Basin is
the lowest-lying point in
Major types of basins
The major types of basins are :
River drainage basins,
River drainage basins
A river drainage basin is an area
drained by a river and all of its
tributaries. A river basin is made
up of many different watersheds.
A watershed is a small version of a river basin. Every
stream and tributary has its own watershed, which
drains to a larger stream or wetland. These streams,
ponds, wetlands, and lakes are part of a river basin.
The Mississippi River basin in the U.S., for instance, is
made up of six major watersheds: the Missouri, Upper
Mississippi, Ohio, Tennessee, Lower Mississippi, and
Every river is part of a network of watersheds that make up
a river system’s entire drainage basin. All the water in
the drainage basin flows downhill toward bigger rivers. The
Pease River, in northern Texas, is part of the Arkansas-Red-
White watershed. It is a tributary of the Red River. The Red
River is a major tributary of the Mississippi River, which
flows into the Gulf of Mexico.
The Amazon Basin, in northern South America, is the
largest in the world. The Amazon River and all of its
tributaries drain an area more than 7 million square
kilometres (about 3 million square miles).
Structural basins are formed by tectonic
activity. Tectonic activity is the movement of large
pieces of the Earth’s crust, called tectonic
plates. Tectonic activity is responsible for
such phenomena as earthquakes and volcanoes. The
natural processes of weathering and erosion also
contribute to forming structural basins.
Structural basins are usually found in dry regions.
Some structural basins are known as endorheic
basins. Endorheic basins have internal drainage systems.
This means they don’t have enough water to drain to a
stream, lake, or ocean. The water that trickles into
other types of basins evaporates or seeps into the
When enough water collects in an endorheic basin, it can
form a very salty lake, such as the Dead Sea, between
Palastian and Jordan. While water evaporates into
the atmosphere, minerals remain. The remaining water
becomes even saltier. The Dead Sea is one of the saltiest
natural body of water on Earth. Its shore, about 400 meters
(1,300 feet) below sea level, is Earth’s lowest dry point.
Sedimentary basins are a type
of structural basin that aren’t shaped like
typical basins, sometimes forming long
troughs. Sedimentary basins have been filled with
layers of rock and organic material over millions of
years. Material that fills up the basin is
called sediment fill.
Sedimentary basins are key sources of petroleum and
other fossil fuels. Millions of years ago, tiny sea creatures
called diatoms lived and died in ocean basins. Eventually,
these ancient oceans dried up, leaving dry basins.
The remains of the diatoms were at the bottom of
these basins. The remains were crushed under billions of
tons of sediment fill, over millions of years. In the right
conditions, the pressure of the sediment fill turns
the diatom remains into petroleum.
The Niger Delta sedimentary basin, in the countries of
Nigeria, Cameroon, and Equatorial Guinea, is one of the
most productive petroleum fields in Africa. In North
America, the Western Canadian Sedimentary Basin is one
of the continent's largest suppliers of gas and coal.
Ocean basins are the largest depressions on
Earth. Edges of the continents,
called continental shelves, form the sides
of ocean basins.
There are five major ocean basins, coordinating
with the major oceans of the world: the
Pacific basin, the Atlantic basin, the
Indian basin, the Arctic basin, and the
Southern basin. Many smaller basins are often
considered oceanic basins, such as the North
Aleutian Basin, between the Pacific and Arctic
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