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The surface of the earth is covered by land
and water. We have special names for different
kinds of natural features, or landforms, on
the earth's surface. Come explore with me
the earth's landforms!
The two largest types of landforms are continents
and oceans.
Continents are any one of the largest landmasses
in the world. Traditionally, the Earth is
divided into seven continents. From largest
to smallest, they are Asia, Africa, North
America, South America, Antarctica, Europe,
and Australia.
Oceans are large areas of salt water between
the continents. Although all of the oceans
are connected to each other, making them one
big ocean, we divide them into five smaller
oceans that are separated by their location
and the way the water in them moves. These
oceans are the Arctic Ocean, the Atlantic
Ocean, the Indian Ocean, the Pacific Ocean,
and the Southern Ocean. Oceans are huge: together,
the oceans cover about 70% of the earth. The
Pacific ocean is both the largest and the
deepest ocean - it covers 1/3 of the Earth's
surface.
Smaller landforms are created in a variety
of ways. Erosion from wind and water can wear
down the earth. Volcanoes and shifting tectonic
plates can create new land, or change the
shape of old land. Let's take a look now at
some of the different landforms and bodies
of water that cover our planet.
Mountains are some of the biggest and most
recognizable landforms. They have steep sides,
and high peaks that stand out from the land
around them. Smaller, less steep landforms
are called 'hills.' Mountains are usually
formed when rock layers are pushed together
from opposite sides, forcing the land up in
the middle. The low areas between mountains
are called valleys.
Mountains may also be formed by volcanic activity,
when lava and other materials build up on
the surface, but mountains aren't the only
landforms that can be made by volcanoes. When
lava flows into the sea, it can create brand
new land. Sometimes, volcanoes in the ocean
create islands.
An island is a piece of ground that is completely
surrounded by water. Islands can be big or
small, in any part of the world. The biggest
island in the world is Greenland. Australia
is bigger than Greenland, but it is so big
that it is called a continent instead of an
island.
Two more landforms that involve a little land
and a lot of water are peninsulas and ithsmuses.
An isthmus is a narrow strip of land with
water on both sides, connecting two larger
pieces of land. A famous example is the isthmus
of Panama, that connects North America to
South America.
A peninsula is a piece of land that has water
on three sides, but is connected on the fourth
to the mainland. Two well-known peninsulas
are Italy and Florida.
Coastal areas have their own types of landforms.
Bays, coral reefs, and lagoons are all
landforms that may be found on or around the
coasts.
Another type of coastal landform is the estuary.
An estuary is where a river meets the sea.
There, the saltwater from the ocean mixes
with the river's fresh water, and the river
spreads out, twisting and turning, wider and
wider. Because of the way it spreads out,
water in an estuary is generally shallow,
which allows sunlight to penetrate all the
way to the bottom.
Rivers are important natural features themselves.
They are fed by rain, or melted snow. The
water in rivers is called 'fresh water' because
it is not salty like water in the oceans.
They begin in high ground, usually in hills
or mountains, and follow gravity's pull down
to lower ground. Smaller streams meet and
join together, forming larger streams and
rivers. These larger rivers join together,
too, becoming larger and larger until they
finally reach the ocean.
Sometimes rivers will flow into large bodies
of water before they reach the ocean. A large
body of water surrounded by land is called
a lake. A small body of water surrounded by
land is called a pond. Not all lakes and ponds
get their water from rivers: some are filled
only by rainfall. Most lakes are filled with
fresh water, but some lakes are salty. One
famous example of a salty lake is the Great
Salt Lake in Utah.
Another type of landform is a plain. Plains
are large areas of flat land with no hills
or mountains in them. The Great Plains, in
the mid-United States, is a good example of
a large plain.
The last landforms we're going to learn about
today are plateaus. Plateaus are large areas
of raised land that are flat on top. Plataeus
may be caused by volcanic activity beneath
the Earth's surface. Sometimes the pressure
of the magma beneath isn't strong enough to
break through the crust and create a volcano,
so instead, the land is pushed upwards. Plataeus
may stand all by themselves in otherwise flat
land, or may sometimes be close to other plataeus.
There are many more types of landforms that
we didn't have time to discuss. Landforms
are all around us!
I hope you enjoyed learning about landforms
with me. Goodbye till next time!
