Our world, the earth, from space it’s easy to see the distinctive pattern of land that makes up the continents. North America, South America, Africa, Antarctica, Europe, Asia and Australia. Giant landmasses separated by oceans that stabilize the environment with hospital weather patterns, suitable for civilization and cities to evolve and prosper. Now imagine our planet ravaged by storm forced winds, subjected to extremes of temperature, giant freezes, heat waves and droughts. A world where cities are crushed and destroyed, where Africa tramples New York underfoot, and London freezes at the North Pole. The world as we know it, will be unrecognizable.
This is not our earth after a devastating global disaster; this is how nature will shape our planet many millions of years into the future. This incredible remodelling is just part of a natural cycle that has shaped the earth for the last four billion years and will continue to do so until the sun finally destroys its surface once and for all.
Previously when I had posted The Romance and the Science of our Moon,
Practical Hermit had come up with a very interesting theory and question.
do you think the impact that created the moon may have also been responsible for shoving all the lighter rock to the opposite side of the planet and creating the original panengae ??
Monday March 3, 2008 - 07:30pm (PST)
Also, as we had conversation back and forth he added
fluid dynamics in a highly viscous medium,it was a passing thought...it's a good question....gravitational attraction by the newly formed moon Must have been a major initial influence in continental drift...given the conditions-still having teraforming in mind regarding the question.
And so I thought I might as well put it all together into a post, since yes the moon does have a major influence on our earth, and although it is only a relatively new discussed theory among scientists that earthquakes are the influence of the moon, although this is still only a theory and still on the debating table.
Pangaea is a latecomer of the super continent formation, 300 million years ago, but by no means the last super continent. Vaalbara is the first super continent formed something like 3.6 billion years ago.
Ur (~3 Ga ago, though probably not a supercontinent; but still however, the earliest known continent. Ur, however, was probably the largest, perhaps even the only continent three billion years ago, so one can argue that Ur was a supercontinent for its time, even if it was smaller than Australia is today). Still, an older rock formation now located in Greenland dates back from Hadean times.
Pangaea – Colliding Continents
Today, our continents may seem solid, safe and forever fixed in place, but they are none of those things. These great landmasses are constantly on the move. If you could speed up the globe over the past billion years you would see the continents sailing across the globe, powerful forces deep within the planet rib the continents apart and then smash them together in an ever-changing cycle of death and rebirth. Oceans disappear, mountains crumble and rise again. Landmasses form and reform.
To understand how the continents shape our world we must first travel back in time to the very birth of the earth. F.4 billion years ago the earth is created from the debris left over from the formation of the sun (see also Death of a Star) Dust and debris collide and clump together, once these clumps grow into objects about half a mile in diameter they create enough gravity to attract more material. Slowly these clumps grow into as many as 20 planets. As these new planets orbit the sun they begin to collide. One collision with the planet Thea which creates the moon obliterates the surface of the earth. The energy of the collision makes the earth incredibly hot.
Earth is a massive molten ball of boiling lava; this is primeval hell, with thousands of asteroids and comets bombarding our world. But deep within our planet a process starts that will lead to the first land. The heaviest elements led and nickel sink down towards the centre of the earth to form a molten core. The lighter elements including oxygen and silicon rise towards the surface where they erupt in volcanoes of molten rock. Slowly the earth surface cools. Molten lava solidifies to form patches of crusts, the seeds of the first continents. But even as the first land is born it faces a battle to survive.
We were being bombarded by a large number of asteroids early into the history of our planet, so there is a lot of dynamic change from being walloped from giant impacts disturbing things. Preserving and new-formed land chunk would be very low. Eventually as the barrage from asteroid slows down land has a better chance to form and remain allowing the surface of the earth to cool and harden. But the earth is missing one vital ingredient oceans. From where earth got its water is a controversial topic but most scientists now agree that meteorites contain quite a lot of water.
When our planet was approximately 150million years old, and the first primitive land masses have formed, they’re not like the seven instant recognizable continents of today, the are just small rafts of rock floating on the mantel. But now a type of rock appears on the earth’s surface that will form the nucleus of the future continents, a rock that’s buoyant enough not to sink into the bowls of the earth. Granite. The very first continental nuclei can still be seen in Africa, as well as North America and Australia, they are called cratons. (A craton is an ancient raft of rock that floats on the mantel and around which a continent will grow.) The Kaapvaal Craton in Africa stretches for 463,000 square miles, almost twice the size of Texas.
But cratons are not the only factors at work more powerful forces are building up deep within the planet. Forces that have the power to rip apart landmasses and smash them together, changing the face of the planet forever.
The surface of the earth, the crust is made up of a giant jigsaw of interlocking pieces, called tectonic plates. The separate plates themselves sit on a mantel, a layer between the crust and the earth’s core. Although the mantel is made of rock the heat and pressure deep down makes it flexible enough to allow the plates above to move up to several inches per year.
Evidence of the theory of continental drifts was first proposed in 1912 by German Scientist Alfred Wegener. He noticed that identical fossils were being found oceans away from each other. Wegener noted that a fresh water organism cannot cross a salty sea so if you find a fresh water organism or a land creature greatly separated by distance they must once have been closer together. By mapping which fossils were identical on which continent scientists can map how the continents had drifted.
Plate tectonics is powered by heat. The centre of the earth is 10,000°F, that’s as hot as the outer parts of the sun. Much of this heat is left over from the collision and massive bombardments of the early days of the earth, the rest comes from radioactive decay of heavy elements in the core. Heat escaping from the core creates convection currents in the next layer of the earth, the mantel. The process is like a lava lamp where heat from the bulb at the bottom creates convection currents in the oil pushing the synthetic lava upward. The heat melts part of the mantel and sends plumes of magma and molten rock rising to the surface. It rises between the cracks of the plates creating new rock that pushes the plates apart.
Today the majority of this new rock forms under the sea creating vast inter-connecting volcanic mountain ranges that extend to all the major oceans in the world.
Water, a single drop of it is a miracle, colourless, tasteless odourless, part of every living thing on this planet. And it’s been here since almost the beginning of the birth of the earth. It’s been belched out of volcanoes in the form of vapour, risen to great heights and fallen back to earth as rain, spent life returns to the soil, to rivers and to the sea, perhaps to be sucked down into the molten earthy bowel.
A journey that each molecule in just one drop may have taken thousands of times over millions of years. In it life teams and that’s just a drop in a bucket. And what a bucket!
No other planet in this solar system can lay claim to this strange blue liquid that made life possible, and can also destroy it. More than 70% of the surface of this planet is covered with water. And that’s just the surface. In volume water fills up 320million cubic miles some 95% of the liveable habitats on this earth are in the ocean.
Five different oceans dominate the globe, the Arctic. Atlantic, the Indian, Antarctic, and the stupendous Pacific, mother of all oceans. All of these bodies of water however are profoundly connected to each other that most Oceanographers refer to it as the world ocean. A single marvellous complex entity, it is tossed by wind, tugged by the moon, driven by invisible conveyer belts and warmed by the sun. It can never rest.
A mere substance so enormous, it can take the form as solid, liquid or gas. To make matters even more dizzying and complex the ocean energies reaches high into the atmosphere, each day they absorb enough of the sun energy to feed the world’s oil demand three times over. The equivalent of two hundred and fifty billion barrels of oil. Each day a trillion tons of water evaporates taking millions of megawatts of potential energy into the atmosphere. The results are titanic.
(The continuance of our Ocean might come up in another blog sometimes in the future)
One range can clearly be seen at the bottom of the Atlantic Ocean along the Mid Atlantic Ridge. It stretches more than twelve thousand miles from the sub Antarctic to the Arctic. It comes to the surface in some places; Iceland was created from volcanic lava. It’s one of the few places on earth where one can see continents being pushed apart by about an inch per year. So by the end of the century Europe and America will be almost eight feet further apart.
When the first proto continent formed there were several inter connecting tectonic plates constantly bumping and grinding against each other. Pushing the new land over the planet. Today the earth has over a dozen plates, some colliding together, and some moving apart. They are powerful enough to move a continent the size of North America over three thousand miles in two hundred million years. That’s fifteen miles every million years.
The earth – 3.4 billion years ago – and plate tectonics pushes the proto continents together, they combine to form ever-larger tracks of land. Scientists suggest that cratons combined with other cratons to form a super continent, a huge continuous stretch of land, it’s called Vaalbara. Scientists aren’t sure of its exact shape or size since only a few pieces like the one in South Africa remain. But Vaalbara’s days are numbered. A rising plume of heat is growing beneath it and it’s about to rip its first super continent into pieces.
2.7 billion years ago – Vaalbara the world’s first super continent still dominates the planet but plate tectonics powered by heat from the earth’s core is about to split it apart. Rock is a good insulator when the rock gets very large it traps heat underneath it. As it gets hotter and hotter a plume of super heated magma swells up beneath the giant continental mass. The temperature continues to rise and pressure in the mantel increases eventually the crust can no longer contain the pressure and the hot lava breaks through ripping the land apart. You can see this process happening today in Africa. Deep from the earth’s core is ripping the continent apart. A giant rift valley runs from the Red Sea down to Mozambique, giant cracks are opening up the land. Volcanoes like Kilimanjaro mark spots where molten rock have risen to the surface in the past. In ten million years the eastern half of the continent will have split away.
The molten lava trapped beneath the giant super continent Vaalbara eventually smashes through the surface rocks and the continent ruptures into several smaller pieces where these bits of land sail across the earth but nobody knows what happens to them or what the planet looks like at this time.
The earth is entering the dark ages; it is over two and half billion years since the earth was formed. It will be over a billion years before another super continent forms.
The earth is entering a deadly cycle of destruction and rebirth.
The separate pieces travel away from each other pushed by the creation of new land at the ridge between plates, because the earth has a constant surface area the same amount of earth created must be absorbed into the earth. This process happens at subduction zones and injunctions of plates. At a subduction zone the crust darts down into the mantel to be melted to form new rock. When the plate subducts into the earth it brings two pieces of land together, when they collide a new super continent starts to form.
It is now 1.1 billion years ago and the next known super continent has formed, its name is Rodinia and it holds almost all the rocks on the continental surface of the earth. Still no one knows exactly what it looked like but at its heart is an area that will eventually become North America. Three hundred and fifty million years later the cycle of annihilation and creation starts again as the built up of heat beneath the surface of the earth tears Rodinia apart. When Rodinia splits, it forms several smaller continents that for millions of years drift apart and then drift back together again to form Gondwanna a super continent in the Southern Hemisphere. Eventually after several hundred million years Gondwanna slowly splits apart, plate tectonics pushed the land together to create the world’s last super continent. It’s a huge land mass known as Pangaea.
Pangaea
All the continents we know today are here joined together. Geologists are able to plot the continents’ relative positions because three hundred and fifty million years ago there are numerous species on earth. Each living in distinct regions. The fossil records show that North America and Europe rest next to one another. The land where New York now sits is next to Morocco in North Africa. The Atlantic Ocean does not exist. The East Coast of South America nestles against the Western Coast of Africa, while Australia, India and Antarctica are joined to the south east of Africa.
Pangaea is one giant continuous landmass, it not only makes the whole world look very different it also has a very dramatic effect on the climate. Because much of the land is located far from the sea the climate of the interior changes radically from season to season. It gets very hot in the summer time and extremely cold in the winter.
You don’t have moderating influence from the ocean that we have today so it’s a very different world. And it’s a world in some ways is harsher and less hospital at least to life on land.
It’s thought the climate change caused life on Pangaea’s formation may have played a role of the largest mass extinctions on earth. This event known as the Permiantriasic mass extinction wipes out about 90% of all life on earth.
Pangaea is called the mother of all mass extinctions
Two Hundred and fifty million years ago and the super continent of Pangaea is breaking up, the continents we know and recognize today begin to take shape, over the next of tens of millions of years South America drifts away from Africa, North America away from Europe, Australia splits off from Antarctica and heads north to warmer climates. The positions of our continents are becoming familiar although their distinguishable features are not.
The world’s vast mountain ranges, the Alps, the Himalayas and its great valleys like the Grand Canyon are yet to form. They will emerge out of one of the biggest battles in nature.
Earth, one hundred million years ago – a battle is raging between the continents that will change the face of the earth forever and create some of the most extraordinary geological features on the planet.
they’re not like the seven instant recognizable continents of today, 
