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The Antarctic is much colder than the
Arctic. On average temperatures in the Antarctic are 50-80 degrees Fahrenheit
lower than the Arctic. Although both areas receive the same amount of sunlight,
the ice and snow in Antarctica reflect much of the heat away, causing it to be
so cold. The winds also play a large factor in the temperature. Every increase
of 1.2 mph in wind speed drops the temperature a further 1.8 degrees Fahrenheit.
Even in summer a person’s breath freezes as soon as it leaves the body.

The Antarctic is also a desert. Even
though it contains 70% of the world’s fresh water, this has been built up over
thousands of years. The interior of Antarctica receives less than the equivalent
of two inches of rain each year. Of course, it doesn’t come in the form of
rain, but as snow. This makes inland Antarctica one of the world’s driest
deserts. The Air is too cold to hold moisture, which is why there is so little
precipitation. Even on the coast, where the temperatures are higher, there is
less than the equivalent of 15 inches of rain per year.

The Antarctic Peninsula, in West
Antarctica, directly south of South America has the highest temperatures. During
a really hot summer there, the temperatures can reach as high as 59 degrees
Fahrenheit, but the summer average is around 50 degrees. You can compare that to
the winter in Arizona. The average summer temperatures in the warmest place in
Antarctica are much the same as the average winter temperatures in the warmest
place in Arizona!

The cold in Antarctica makes it almost impossible for
humans to live there. Although the temperatures are so low, a person wearing
dark clothing can actually feel quite warm, as the clothes absorb the heat of
the sun. Any exposed skin, though, freezes. When it is frozen blood cannot reach
it and it dies. This is known as frostbite. The sun reflecting off the ice also
causes problems, and people must wear dark glasses outside or they may become
blind, from the ultra-violet rays. Add to the problem of the cold and sun, the
wind. Walking against such strong winds is very tiring. The combination of all
these factors is what caused so many explorers to fail to reach the South Pole
when they tried. In such cold climates humans must consume a lot of food to
maintain their energy. Early explorers often had to give up because they were
too cold, too exhausted and too hungry to go on. They had to carry or pull al
the food and clothing they needed on sleds. That meant spending more energy. It
was extremely difficult to make a balance between the energy needed to pull the
food (so requiring more food) and taking just enough food to give enough energy.

Related Articles:
Antarctica
Animals in Antarctica
Early Explorers in Antarctica
Penguins 

Continental Drift

#3: Recycling

By the early 1960’s it was established that the earth was making new
crust, on the ocean floor, all the time. However, since the earth is not
expanding, where is this new land going?

The answers began to appear in 1964, following a major
earthquake in Alaska. Geologists visiting the area immediately after the quake
were, at first, confused by reports about changes in sea level. Some areas were
claiming that the sea level had fallen, and others that it had risen. Despite
searching, the geologists could find no evidence of a crack in the earth’s
surface. A quake with a magnitude as great as this had to have an associated
fault line (crack), but where was it?

Barnacles

A particularly observant geologist noticed a strange
phenomenon. Along the entire coastline, there was a line of barnacles, still
living, way above the highest level that the sea reached. In some places it was
as much as 20 feet above the present levels of water. The fact that the
barnacles were still living meant that they had been in seawater recently. From
this, scientists were able to state that the sea level at the coast had
definitely fallen, or more accurately, the land had risen.

Inland Flooding

Further inland though, the story was the complete opposite.
Areas, which had been dry for years were suddenly sitting under water. There was
no doubt that these areas had dropped during the earthquake.

The Fault Line

By drawing diagrams, and making models, the scientists came
to the conclusion that the fault line must lie under the earth’s surface. The
areas of uplifting and sinking indicated that the line ran from an area just off
the coast, diagonally downwards, under the land. They also noticed that just
where their theoretical fault line was, there was a deep trench in the ocean
floor. Trenches like it can be found all the way around the Pacific Ocean rim.

Putting it Together

Now the scientists had the following information:

• The earth makes new crust on the ocean floor
• The crust moves outwards as newer crust is formed
• The earth is not getting larger
• There is a trench all the way around the Pacific Ocean
• There is a fault line running from the trench, under the land
  mass

It didn’t take them very long to decide exactly what was
happening to the extra land. It was disappearing down, under the
continents, at the trenches. The trenches are like a huge crack in the ocean
floor, where the newer rock slides under the older rock. As it slides, the
weight of the older rock pushes it downwards. Eventually it reaches the outer
core of the earth, which is extremely hot and molten. Here it heats up and
becomes molten, joining all the rest of the molten rock, to become magma again.

Recycling

In a way it is like a natural recycling plant. At the mid
ocean ridge, hot molten rock, or magma is forced upwards. As it comes into
contact with the cool ocean it solidifies, becoming new solid rock. The rock is
gradually pushed outwards my more rock as it forms. The entire ocean floor is
being pushed outwards towards the continents. At the edges of the continents,
the new rock is pushed downwards, under the continents. The solid rock heats up
and becomes magma again. Then the cycle begins all over again

Is That the End of the Story?

It might seem that the story is finished now. We have
successfully explained how the continents were pushed apart. We have proved that
the ocean floor is constantly being renewed. We have seen where the extra ocean
floor goes. However, it isn’t quite the end of the story. The theory of
continental drift once it got this far, became known as the theory of Plate
Tectonics. So now we need to look at Plate Tectonics, and also check those facts
about disappearing earth. Not all of it goes down under the continents, some of
it goes up!

Continental Drift

#4 Plate Tectonics

After 50 years of investigating, Wegener’s theory of Continental Drift became the fact of Plate Tectonics. The earth’s crust is made up of huge areas, all moving, known as plates. The edges of the plates, or plate margins, are where all the action is. Sometimes they cause earthquakes or volcanoes; sometimes they build mountains and sometimes the swallow up the earth’s crust.

The edges of the plates are known as the plate margins, or plate boundaries. Depending on the type of boundary, different things happen. There are three main types of Boundaries.

Spreading Boundaries

There are two types of spreading boundaries:

Ridges, where new rock is formed, pushing the plates apart, and Rift, where the plates pull apart, and the earth between them sinks.

On the ocean floor the plates are spreading. All along the mid ocean ridge, volcanic activity is pouring new lava out onto the seabed. As it hardens, it becomes new rock, gradually pushing the crust, on either side of it away. Another type of spreading boundary is the African Rift Valley. As the two plates are moving apart, the earth between them is becoming stretched. As it stretches it sinks, because it is thinner. It is a little bit like taking a piece of gum, and stretching it out. The pieces in your fingers stay thick, but the piece in the middle gets thinner and thinner, as it is stretched.

Converging Boundaries

Converging (coming together) Boundaries, are where two plates are banging into each other. What happens when they collide depends on the type of plate they are.

In a subduction zone one plate is being pushed beneath the other. It happens when a heavy plate hits a lighter plate. The heavier plate is pushed under the lighter one since it is more dense. This often happens where continents meet the ocean. As the heavier ocean crust is forced downwards, it takes water with it. The water causes the rock to melt at lower temperatures than normal. The pressure inside the earth is much greater than at the surface, it increases the deeper you go. The new molten rock tends to rise to the area of lower pressure, sometimes forming volcanoes. It is not uncommon to find volcanoes along a converging boundary, on the side of the heavier plate.

In a deformation zone the area where the plates meet is being crushed and pushed upwards. It happens when the two plates are almost equal in weight. Instead of one plate being pushed down under the other, they smash into each other, causing the edges to rise upwards. It is very similar to two cars crashing together, head-on. As they hit each other, the front ends crumple, and lift upwards. In this type of boundary huge mountain ranges are formed. The best example of this is the Himalayan Mountains. They were formed when the Indian Plate crashed into the European Plate. The two are still being forced into each other, and the Himalayan Mountains are slowly becoming taller.

If you think about it hard enough, you can probably see that plates with a spreading boundary on one side must have a converging or transverse boundary on the other side. The earth’s crust is moving and changing all the time, but the upward or downward movement of converging boundaries, stops the earth from growing larger. As the plates slip and slide over and under each other, they keep the size of Earth constant.

Transverse Boundaries

The last type of boundary is neither spreading nor colliding. The edges are sliding past each other, sideways. As they slide past each other they cause a huge crack in the surface of the earth. This crack, or fissure, is known as a fault line. Probably the best-known example of this is the San Andreas Fault, which is found in Western California. As they slide past each other they sometimes cause earthquakes. Areas with fault lines have more frequent earthquakes than other places.