Why Does The Earth Map Looks Like A Jigsaw Puzzle ?

Hey there, the earth resembles – in places – a jigsaw puzzle because the land masses (as explained above) were once joined together.
In other places it is less like a jigsaw puzzle. You are probably speaking mainly of the borders of the Atlantic ocean. Where (in particular) Africa and South America look like they could click back into place.
The reason areas like this look more clear-cut is because there edges are what we call ‘passive’. Nothing much has happened to these edges and there is very little geological activity along them.
The main area of movement in the Atlantic is a spine running down it’s middle formed from 100’s of volcanoes and faults (big cracks) in the surface of the earth. The surface of the earth is formed of the crust – and under the Atlantic this hard cold crust is only 10 or so Kms thick. Below that – is the lithosphere (a thick bad of hot solid rock) and the upper mantle (Hot plastic rock). The hot material beneath the crust is what bursts up through the volcanoes. Also – the constant shifting motion of this hot material splits and spreads the Atlantic open along it’s central ’spine’ known as the Mid-Atlantic Ridge.
The oceanic ridge that divides the Atlantic runs all the way down from Spitzbegren north of Europe – past Iceland in the North Atlantic and down round Afric, and up into the Indian ocean. All along the ridge the underlying movement of hot material spreads the crust apart.
But of course – if the crust were always spreading; if new crust was always forming; then the earth would get bigger; wouldn’t it?
Is the earth getting bigger? In a word no. Satellites have measured the earth and there is not perceptible increase in size. So how can these new ‘bits’ of land form? Well it means other bits have to disappear – and they do.
The oldest ocean crust on earth is barely 200 million years old. The earth is 4.5 billion yeats old. So where did all the old ocean crust go?
Well just as new ocean crust forms at the ridges – so in places ocean crust is consumed back into the earth. But NOT along the boundary of Africa/S.America. Because as we said before that is passive.
The boundaries of the Pacific (W.Coast US, Japan, Indonesia etc…) are a different story. These areas are SO geologically active – that geologists call them the ‘Ring of Fire’.
1883 – Krakatoa, 1815 Tambora, 1980 Mt St. Helens, the 1995 Kobe Earthquake, the 2003 Boxing day Tsunami… these are among the 1000’s of geological events that have cost millions of lives over the past centuries around the pacific. But why?
Well – that hot material under the crust? The Asthenosphere/Upper Mantle? It’s hot and it’s soft. Once upon a time the Pacific was like the Atlantic – spreading away. Peace reigned along it’s passive margins and it became a globe girdling ocean – Panthalassa. Panthalassa was the opposite of Pangea – Pangea dominated one third of the worlds surface – Pathalassa was the open ocean around it.
Then the Atlantic was born through rifting along central Pangea. Pangea began to undo like a zip.To the west the N. Am, and S. Am began to move west – to the east europe/asia/africa/india/australia/antar… began to move east. Rifting spread – Australia broke away – so did antartica. India began to collide with Asia – thrusting up the himalayas. But what about Pathalassa?
Well the continents – pushed by a feverous Atlantic began to ride over her. Her crust buckled and was pushed back into the soft mantle – taking water and mineral with it. As the crust sunk 10’s of kms back into the earth it cracked and dried out in the heat – causing massive deep earthquakes which shook the margins of the dying ocean. Pathalassa became the Pacific – invaded by Australia and slowly encroached upon my the Americas and Asia – the Pacific is a dying ocean. She has a ridge like the Atlantics – and she is producing crust – but just as fast as it is produce so it is swallowed at the edges. The material that is taken back into the earth changes the chemistry of the hot material at depth. It becomes lighter – and like the bubbles of gel in a lava lamp – under heat the chemically altered rocks melt and begin to rise. They escape from the surface through massive volcanoes like Fiji in Japan or Rainier in Washington state. Hence cracking crust makes earthquakes and melting mantle volcanoes – but only along the pacific’s ACTIVE margins. As the continents move closer and swallow mor crust – volcanoes and volcanic islands collide with them and mis-shape their margins. That is one reason why active margins do not fit so well because they have volcanic ‘igneous terranes’ plastered all over them
You can imagine that I could write more – but will stop now. So – that is why some parts (passive margins) preserve good fits , and other parts (active margins) less so.

Yes – it was one land mass called Pangea.
It comprises a number of tectonic plates, that move apart and form the continents we see today.
The plates are still moving apart and in some places colliding – slowly – which builds up pressure. Eventually the pressure gets too much and the energy is released – an Earthquake.

Yes! The earth was one chunk of land surrounded by the ocean. What happend was over a period of millions of years this land mass was broken apart into what we now call our continents. This happened by various factors such as: The ocean, (erosion) and Seismic activity (earthquakes). Hope your a bit wiser now!

There’s one fairly common assumption about Pangaea that should be avoided and, as I’ve come across it in some books, I think I’ll mention it here. Sometimes, it’s assumed that the continents all formed together and then broke up. That sort of idea leads people to wonder why.
The thing is, they didn’t form like that. They simply happened to drift together, and most land formed one mega-continent for a while. The continents partied together through the Triassic and into the Lower Jurassic, but then Pangaea gradually broke up again. Prior to Pangaea, they’d already been drifting around in various configurations.

WHAT?
The earth is spherical and hangs in space.
A jigsaw is a pile of squiggly cut cardboard in a rectangular box.
The similarity escapes me mate.

Yes, because it was one landmass, fractures and continental drift of the plates have resulted in separated landmasses which resemble a jigsaw because they once fitted together.

yes it was once a supercontinent called pangea. at least thats what scientists theorize.

The earth map looks like a jigsaw puzzle because a very long time ago, the different continents on earth are together. It is one piece of land before. Maybe there is snow everywhere a long time ago but the snow melted and turned into water. Other say that the piece of land before time separated from each other that is why when you look at the world map, if you place the continents together, it fits.
That’s the only thing I can say.

Scientists theorize that the earth was once a large mass of land called Pangea. Then it broke up into two super continents called Gondwana to the south and Laurasia to the north because of plate movements. This theory is called the continental drift theory and it was presented by alfred wegener. Scientists theorize that this may be possible since
a) the continents seem to fit perfectly like jigsaw puzzles.
b) fossils found on the connecting pieces are similar
c) age of the rocks along the coastlines are the same
Today, scientists say that it is still happening. The mid atlantic ridge is increasing in size by 5-10cm per day. This means that the pacific is closing up.

Have a look at this animation. It is only a gif. Just refresh the page to restart it.http://www.ucmp.berkeley.edu/geology/ani…
There are more here including AVI and quicktime that you can pause and rewind:http://www.ucmp.berkeley.edu/geology/tec…
It is really interesting how in the last 70 million years or so the part that will become India storms its way up through the Pacific and collides with Asia. That is what created the Himalaya mountain range.http://www.classzone.com/books/earth_sci…
If you look on Google earth and do a fly by over Everest you can really see how it is just one huge crumple zone. It never ceases to fascinate my students!
Ori
PS Trevor is right (below), you can see Pangea forming on the animations about 300 million years ago and then splitting up again about 190 million years ago. Before that they were moving around just as they do now. guess at some point they will come together again, maybe when The American plates move all the way across the Pacific area to meet the plates in the East Asian area. It’s going to be a few million years yet though!

because millions of years ago it was all one mass of land but many things have happened since the earth was born,earthquakes,volcanoes,flood,the ice caps melting and even meteors and the sun and moon gravity influences on the earth manny of the earhts have seperated to form seperate islands for instance did you know great britain was attacked to what we care france and there was no water between us,in fact we in england far deep in the bottom of the ocean is still attacked to france it’s just the way that the sea has risen over millions of years and flooded lowlands and seperated them and this has happened over the whole of the earth and it’s great continents so the reason it looks like a jigsaw is it is a jig saw,and if a gaint hand were to appear all the peaces would fit back to gether

life is jigsaw puzzle