Category: Geography Articles

Since a circle has 360 degrees, a compass has 360 degrees, too.
North is at 0 degrees.
The cardinal points divide the circle into 4 equal parts.
360 divided by 4 = 90, so the cardinal points are 90 degrees apart.
Therefore:
North=0East=90South=180West=270

The intercardinal points mark the midway point between the cardinal points.
90 divided by 2 = 45
Therefore:
NE = 45SE = 135SW = 225NW = 315

Note that the cardinal points are also 90 degrees apart, because there are four of them.

The secondary intercardinal points mark the midway points between the cardinal points and intercardinal points.

• The cardinal and intercardinal points are separated by 45 degrees.
• 45 divided by 2 = 22.5


Therefore:


• NNE = 22.5
• ENE = 67.5
• ESE = 112.5
• SSE = 157.5
• SSW = 202.5
• WSW = 247.5
• WNW = 292.5
• NNW = 337.5

Note that the secondary intercardinal points are 45 degrees apart because there are 8 of them.

You could of course work out that each point is separated by 22,5 degrees, and just work your way round the points adding 22.5 to each. How you got the answer is not very important. It is important that you got it right!

  

Although the Ancient Greeks had believed that there was
land to the far South, they had absolutely no proof of it. The very first proof
came in January 1773. At that time, Captain
James Cook, a British explorer, crossed
the Antarctic Circle. His expedition did not see land, but they did see rocks in
some of the icebergs they passed. The presence of the rocks meant that there
must be land. He sailed his ship right around Antarctica but could not get close
enough to spot land. Massive sheets of ice prevented him from getting any
closer.

Following James Cook more and more explorers ventured into
the Antarctic Circle. Antarctica wasn’t going to be easy to discover, though.
It took almost another 50 years before anyone actually spotted land. Fabian von
Bellingshausen was probably the first person to see the continent of Antarctica.
He was a captain in the Russian navy. He spotted it in January
1820; 47 years
after Cook said it was there. He also sailed around the continent. Because he
had larger, stronger ships than Cook, he was able to push further south. He
described the land as a field of ice covered with small hills.

Cook had said that he thought no benefit could be had from
Antarctica. The Russians thought the same. Bellinghausen returned to Russia and
never returned to Antarctica.

News of Bellinghausen’s sighting didn’t reach many
people at the time. Other people claimed to be the first to see it. These
included an American whaling captain and two British naval officers. Most
historians now agree that Bellinghausen was indeed the first person to see it.

On February 7,
1821, John
Davis, became the first person to
land on Antarctica. He was Captain of an American whaling ship. Some Historians
claim the part he landed on is not part of the true continent, but a Peninsula,
or piece jutting out.

At about the same time as Bellinghausen was making his
discoveries a Scot, named James
Weddell, was also discovering things about
Antarctica. He took two sealing expeditions South, and discovered a sea of ice.
He named it after the then King of England, George IV. Last century it was
renamed the Weddell Sea. There was a species of seal named after him, also. It
took 80 more years until anyone managed to get further south than he had. No one
else managed to sail through the Weddell Sea in all that time. Although he began
his expedition at the same time as Bellinghausen, he didn’t reach his
southerly point until three years after Bellinghausen first saw Antarctica.

Weddell’s crossing of the Weddell Sea, in 1823,
marks the end of the first stage of
Antarctic Exploration.

Related articles:
Antarctica

The Weather and Climate in Antarctica
Animals in Antarctica
Penguins

#2: Closer to an Answer

With new technology developed during the world wars, scientists were able
to make detailed maps of the ocean floor.
These maps held the secret to how the continents moved.

The Ridge

After the Second World War, submarines were available,
and so was their technology. Once nuclear submarines were developed
it became important that submariners could navigate safely underwater.
Although there were plenty of maps showing what the world looked like above
the oceans, no one knew much about the ocean floor.
Technology had been developed that allowed the scientists to map the ocean
floor by bouncing sound waves off it. This is called sonar.
After the sonar survey was done, maps were made showing the ocean floor
in great detail. It was soon discovered that an underwater mountain range
stretched all the way around the earth on the ocean floor.
It was also noticed that on either side of this mountain range there was a
very wide trench.

Magnetic Stripes

Scientists had known for some time that the earth has not always been
polarized to the North. Now when you hold a compass the needle points to
the North. In the past though it has pointed to the South. We know that
over billions of years the earth has changed its polarity many times.
Soon after the discovery of the underwater ridge came another discovery.
This was that the ocean floor is made up of strips of rock with different
polarities. A map showing the polarity of the ocean floor in black and white
looks very much like the pattern on a zebra’s coat.
The black stripes indicate normal polarity, and the white strips indicate
reversed polarity.

An important point to remember is that volcanic rock can only be
polarized while it is still molten. Once it cools its polarity is set,
and will not change, even if the polarity of the earth changes.

The Age and Thickness of the Crust

The final important discovery was that the earth’s crust is the same
thickness over the entire ocean floor, and that it has very little build
up of sediment on it. If it had been there for billions of years, it should
have a thick layer of sediment sitting on top of the rock floor.
This led scientists to decide that the ocean floor was in fact quite young,
in comparison to the continents.

Beginning to Believe

It had taken 50 years to get this far, but all of a sudden Wegener’s
theory was making much more sense. Instead of the continents drifting
through the earth’s crust, scientists began to believe that the earth’s
crust had pushed the continents apart.

At first the scientists proposed that new rock was being formed
along the underwater mountain ridge. They decided that the ridge was a
weakness in the crust and that magma, from below the earth’s crust was
being forced upwards through these weak areas and flowing down the sides
of the mountain ridges as lava. Underwater, lava cools very rapidly,
so it was becoming solid, and gradually pushing the crust, on either side
of the ridge away from the mountains. If this could be proved, then it would
explain how the continents had been pushed apart.

The Final Proof

Still there was a problem; nobody could come up with conclusive
proof that this theory was correct. Then finally the scientists managed
to put it all together. They put together two more pieces of information
that had somehow slipped past them, although they had had the evidence for
some time.

• The rocks at the ridges were the youngest, gradually becoming older as they moved apart
• The stripes of polarity on the ocean floor were symmetrical on either side of the ridge.

Now it became clear that the new rock was being formed, and pushing the older rock to the sides,
causing the entire earth’s crust to be pushed apart. Since rock was formed and polarized on both
sides of the ridge at the same time, the stripes were symmetrical.
Sometimes there was a wide strip of south polarized rock followed by a narrow strip of
north polarized rock, and sometimes the strips were the same width.
The most important thing was that the strips were the same on both sides of the ridge;
they were like a mirror image of each other.

So the theory of drifting continents was at least partly correct.
They had at one time been a single landmass, which had split apart.
However, they hadn’t drifted across the ocean, through the earths crust,
as Wegener had thought. Instead they had been pushed apart, with the movement
of the earth’s crust.

A Problem

From Wegener’s theory of drifting continents, we now had a theory of a
spreading ocean floor. But still there was a problem.
If all this new rock was being formed, and pushing aside the old rock,
why wasn’t the earth getting any larger? Where was all this rock going?


   

#1: Fact or Fiction?

In 1912, when the German Meteorologist and Geophysicist, Alfred Wegener first proposed that the continents had started off as one huge land mass, that drifted apart, most people thought he was crazy. In fact he was almost correct, although he had it just a little bit wrong.

The Proposal

Wegener was the first scientist to publish a scientific paper stating
that the world had originally had only one continent. He wasn’t the first person to think like this,
just the first one who was brave enough to announce it to the world. Several people had noticed that the
continents could fit together like pieces of a jigsaw puzzle. This was particularly noticeable with
the West coast of Africa and the East coast of South America. If you could remove the 4,000 miles of ocean
that lay between them they would fit together perfectly. There were other things that pointed to the fact
they had once been joined.

Mountain ridges on one continent could be matched to mountain ridges on the other.
The mountains had the same structure and the same type of rocks.
When you fit the two continents together, the ends of the mountain ranges lined up.

They also knew that fossils belonging to the same animals and plants could be found on different continents,
separated by thousands of miles of ocean.

Wegener, being a meteorologist, also noticed that fossils found in some areas could not
possibly have survived the climatic conditions there. For instance, some of the fossils found on Antarctica,
could never have survived the cold conditions there. Those animals and plants must have originally been much nearer the equator.

What Wegener proposed was that the continents had once belonged to a single landmass,
which he called Pangaea. He then said that something had caused them to split apart and drift through the oceans,
until they came to rest in the positions we know.

The Reaction

The scientific community was perfectly willing to believe that the continents had once been joined together,
but they were not willing to believe that they had drifted through the ocean. After all, everyone knows they go right down to the earth’s crust,
so in order for them to drift, they must have somehow floated on or through the crust.

Instead, they preferred the theory that somehow the ocean floor kept rising and falling,
causing it to reach above sea level at times, forming bridges of land. The animals could walk across these bridges
from continent to continent. The theory was that the continents hadn’t moved, but that the land joining them had long since sunk
below the oceans. This preferred theory wasn’t very believable either. It didn’t explain why the continents could fit together like a jigsaw,
or why mountain ranges stopped on one side of the ocean only to start again on the other side.

Further Investigations and Discoveries

By the time Wegener died in 1930, most scientists still refused to believe his Pangaea theory.
Following the two world wars, and the advances in underwater technology that came with them,
some important discoveries were made. These underwater investigations and their discoveries proved
that Wegener had gotten the theory more than half right. The answer to how the continents had moved
could be found beneath the waves on the ocean floor.

Conclusion

It is now an accepted fact that the continents once began as a single landmass
that slowly separated and became the continents that we know today.
In fact, most people today think that it is fairly incredible that just 40 years ago
scientists thought this idea was crazy.

Finding Your Way

How to Read a Compass

In order to know how to read a map and give directions, and how to find out where something is, you need to know how to use a compass. Most people think of a compass as having 4 points, North, South, East and West, but there is far more to a compass than you would think.

It isn’t enough to tell someone to go right or left, because right or left changes depending on which way you are standing. Stand up now and face the computer screen. Find something on your left. Turn around, with your back to the computer screen and look at the same object. Now it is on your right. How about describing where a building is? Suppose there is a bank, with a post office next to it. Is the bank on the left or right of the post office? That depends on whether you are standing on the street looking at them both, or inside one of them, looking out at the street. As you can probably tell, this isn’t a very good way of describing where a place is at all.

This is where the compass comes into it. First of all we need to know just what a compass is, and how it works. A compass is a tool that shows direction. It has a small, magnetized needle in it that swings. The needle can swing because it is balanced on a post, or because it is floating on oil or water, sometimes it is balanced and floating at the same time.

The needle swings so that one end of it is always pointing to the magnetic north pole. Since the needle has two ends the end that points to the north has some sort of mark on it. Sometimes it is colored red, or has N printed on it and sometimes it just has a fancy arrow on the end.

The compass has four main points, or cardinal points. These are North, South East and West. If you think of a compass like a clock, the North is a 12, East at 3, South at 6 and West at 9. North and South are easy to remember, but East and West are a little trickier. Picture the compass in your head and remember that it spells we, across the middle, so West is on the Left and East on the right, of the compass face as you look at it.

Take a large circular object, place it on a piece of paper, and draw round it. Mark North, South East and West on the paper, and then mark lines coming from the center of the circle to each of the cardinal points. Imagine that you are standing in the middle of the circle, and you are told to travel North, that’s easy; you just follow the line going North. The same thing happens with the other cardinal points. Now take a marker and mark a point on the circle between North and East. How would you tell someone to find that, if they were in the middle of the circle, and couldn’t see it? You couldn’t say go north or east, since they would end up in the wrong place. This is where the intercardinal points come in. These are the points half way between the cardinal points. They are named for the points they lie between. They always begin with North or South. They are Northeast, Southeast, Southwest and Northwest.

Now we are almost done. There are eight more points on the compass, with names. They are called the secondary intercardinal points. They lie half way between the cardinal points (N, S, W, & E) and the intercardinal points (NE, SE, SW & NW). They are named according to the points they lie between. The cardinal point comes first, and then the intercardinal point. The first four are:
North-northeast East northeast East southeast South-southeast

Can you name the rest?

Now you can tell someone fairly accurately, how to get to the point that you marked on your circle. Try drawing some more circles, and marking North on them. Then see if you can name the other points of the compass.

Extra Activity For Older Students

Degrees on a Compass

The compass is divided into 360 degrees, the same as any other circle. If north is at 0 degrees, can you say where the other points are, in terms of degrees?

Hints:

The degrees increase in a clockwise direction. It is probably easier if you work out all the cardinal points first, then the intercardinal points, then the secondary intercardinal points.

Check your answers here.

Antarctica is the fifth largest
continent and lies entirely within the Southern Hemisphere. It has the coldest
climate on earth. It is also the windiest place on earth. The average annual
temperature inland is –70 degrees. The lowest temperature ever recorded on
earth was in the Antarctic, an incredible 128.5 degrees below zero. Now that is
cold! Cold can do strange things. If you drop a solid steel bar it will shatter.
That is one of the reasons that humans cannot live there.

There is no indigenous (native)
population, but during the summer several thousand people live there in research
and weather stations. In the winter only a very few brave scientists stay. James
Cook was the first explorer known to cross the Antarctic Circle, in January
1773. He didn’t see any land, though. Land was probably first spotted by
Admiral Fabian von Bellingshausen and M. P. Lazerev 47 years later, in January
1820. John Davis, captain of an American sealer, was the first person known to
set foot on Antarctica. He landed at a place called Hughes Bay in February 1821.
Hughes Bay is on a Peninsula. Many people claim that the first people to land on
the true continent were Leonard Kristensen and Carsten Borchgrevink, in January
1895.

Almost the entire continent is covered
with ice and snow. If all of the ice were to melt, it is estimated that the sea
level throughout the world would rise by 200 ft. The ice extends out into the
ocean, where is it known as an Ice Shelf. The largest ice shelf, the Ross Ice
Shelf, is larger than the state of Texas, covering 208,000 square miles. As the
edge of the ice meets the ocean, and the warmer water, huge chunks break off
forming ice floes. The ice shelves do not get smaller, though, as the ice flows,
a little like water. Ice behind the shelf keeps pushing the shelf further and
further, so even as pieces break off it is still huge. .The ice is formed by
snow. When the snow falls it doesn’t melt. Each year more snow falls and
compacts the snow below it, turning it into ice. The ice contains 70% of all the
fresh water on Earth.

When people describe Antarctica they
tend to divide it into two different areas, East and West Antarctica.

East Antarctica is made up of a
platform of old rocks, with younger rocks on top. The scientists think that the
platform is about 1,600 ft above sea level. They cannot be sure, because it is
covered with a layer of ice almost 6,000 feet deep, so measuring the exact height
of the land is almost impossible. Without the snow and ice it would be a large
flat plain with two main mountain ranges, one on the coast and one inland

West Antarctica is south of South
America. The land in West Antarctica doesn’t reach as high, and in some places
is well below sea level. All of the ice causes the land to be pushed down. If it
all melted the land would rise. East Antarctica would be mostly above sea level,
but West Antarctica would be made of islands in a sea. The highest parts would
form the islands and the lower parts would form the sea floor. The highest peak
is found in West Antarctica, called Vinson Massif. It is on the coast and is
16,000 ft.

There are a few areas with no ice. These can be found on
the coast and slopes of the mountains. On warm days the rock heats up and melts
the surrounding ice and snow. As the water runs off, it goes down into cracks in
the rocks. Out of the reach of the sun it freezes again and expands, cracking
parts of the rock away. All of the areas with no ice have piles of boulders and
rocks formed in this way.

There are two known active volcanoes in Antarctica. There may be more, but
only two have peaks above the ice. The highest is called Mount Erebus. It is in
East Antarctica on the edge of the Ross Ice Shelf. It is strange to think of an
active volcano beside all that ice.

Related articles:
The Weather and Climate in
Antarctica
Animals in Antarctica
Early Explorers in Antarctica
Penguins

There is very little plant life on
Antarctica. It consists of small amounts of lichen and moss, and some floating
plants in the inland seas. Apart from a few insects, all of the animal life
feeds from the ocean. The largest animal living entirely on the land of
Antarctica is a mite. It is just big enough to be seen without a microscope. It
manages to stay alive by producing chemicals very similar to the anti-freeze
that we put in our cars in winter! The ocean is full of nutrients. Warm water
rising brings the nutrients up to the surface. Those nutrients along with krill,
a small shrimp-like animal are the keys to the food chain in Antarctica.

Fish

Although there are many types of fish
in Antarctica, there are not that many and they are small. However, there are
plenty of cephalopods (octopus and squid). These play an important role in the
diet of some whales, seals, fish, penguins and other sea birds.

Birds

More than 80% of birds in the
Antarctic region are penguins. Some live on ice floes, while others live on
land. The Emperor penguin never steps foot on land. It spends almost its entire
life in the ocean. The female lays her egg on an ice floe, and the male
incubates the egg on his feet. The male has a special flap of skin to protect
the egg, and an indentation in his lower body. He lowers the indentation over
the egg, so the egg is well protected from the cold. The flying birds are mainly
petrels and albatrosses. They make their nests on offshore islands and rocky
areas of coastline. The Arctic Tern flies between the North and South Poles. It
spends from September to March in the Southern hemisphere, enjoying the summer
there, and from April to August in the summer of the Northern Hemisphere. Each
year it flies about 18, 500 miles!

Mammals

The marine mammals in the Antarctic
are mostly whales and seals. There are two main types of whale in Antarctica,
the baleen and the tooth whales. The baleens feed on plankton, and include
humpback whales, blue whales and sometimes minke whales. The tooth whales
include the killer whale and the sperm whale. They feed on other mammals, such
as seals and on fish and even birds when they can catch them.

The seals are mainly four types: Ross’s seal, which is
less than 1% of the population, leopard seals, crabeater seal and Weddell seals.
There are probably about 20 million crabeater seals in Antarctica. They have
specially adapted teeth for sieving krill from the water. The leopard seals are
hunters. They are known to eat penguins, other seals and fish.

Related articles:
Penguins
Antarctica

The Weather and Climate in Antarctica

Early Explorers in Antarctica