How could Pangaea have ever existed?

Question

Think about it for a moment. When the earth was formed how did the highest part of crust only exist on half of the globe. The earth formed with an iron core with equal gravity force from all directions how could one side have a larger lump of land then the other. Wouldn’t gravity make it more evenly spread around the planet? Please don’t answer the question with the answer look at South America and you can see how it fits nicely into Africa.

Answer 1

If you want to see some reconstructions of previous supercontinents, of which Pangea was only one of several take a look at the Paleomap project:

http://www.scotese.com/

Click on the Earth History link on the left side of the page and then click on any one of the time periods listed on the left. You will be able to see the progressive movements of the earth's continental plates over time. You might also want to veiw some of the animations of the movement of the continents.

Most of the data that was used to create these maps came from paleomagnetic reconstructions, combined with stratigraphic data, paleontological data, and other sources. Since the earth's magnetic field is recorded in the rock record it is possible to use magnetic records in rocks like basalt to reconstruct the original position of rocks as they were deposited. There is a long list of references if you would like to read up on the science behind this mapping project.

As for early Earth, there was likely a period when no oceans existed. Gravity would have had an influence, however, gravity is just as much an influence now and we still have moving tectonic plates that are moving several centimeters a year. There would have probably been much more volcanic activity then, and the earth's mantle and crust were probably still forming. Now, several billion years later the Earth has formed into layers, some of which are not solid (the asthenosphere), and this allows plate tectonic motion to continue.

Answer 2

When the Earth was cooling, it did not cool evenly. There are a number of theories as to how the different densities and cooling rates occurred, but I'll go with the easiest. The side of the Earth that faced the sun at its closest point to the Sun would remain marginally hotter than the side facing away. It is entirely possible that the Earth did not have the rotational and revolutionary periods it has today so this could happen. Then the side facing away would cool, leading to a difference in density. It can then be argued that continental drift is merely the equalization of a centrifugal instability. That should explain why the land masses had been on one side of the planetary mass, and then moved to their current locations.

This is not the only theory, but I think it is the easiest to understand to address your concern.

Answer 3

Pangaea wasn't formed as Pangaea. Land masses were formed in many places and floated around the crust separately. It just happened that at one time in earth's history most of the large land masses came together for a period of time before breaking away again.

The mass of the earth is still active, it hasn't reached an equilibrium yet. Gravity is spreading the mass out evenly, the lighter stuff is coming to the surface and the heavier stuff is sinking, its just not finished yet.

The mass of the continents across the surface is relatively insignificant compared to the mass of the whole earth, its sort of like foam on the ocean.

Answer 4

I have heard of a recent scientific theory that the moon was formed by a huge collision with the Earth. The moon is too large to have been caught in the Earths gravitational field. It is actually drifiting away from us every year at a very slow speed. The theory that a large body hit the Earth at an angle which slowed the object down and as it spun around with the Earth and eventually separated and formed the moon. This impact was so large that it liquified the surface of the Earth and could have forced the land mass that eventually became Pangaea to one side of the Earth.

Answer 5

There is good evidence that the Moon formed from the debris created by the collision of Earth and a Mars-sized planet, very early in the history of the solar system. It is possible that this cataclysmic event resulted in a partial re-melting of some of the earth's crust, and perhaps the loss of some of that crust in the collision itself. This could have led to a very assymetrical crustal remnant on which the continents formed.

Answer 6

First off, the initial earth did not have differentiated crust, but somehow, as early as 4.2 billion years ago, continents formed. This is still one of the great mysteries yet solved in geology.

There were several supercontinents before Pangea. Rhodina existed until around 0.8 billion years ago, and Colombia existed around 1.7 billion years ago.

In Rhodinia time, Siberia, Australia, or Antartica (depending on who you ask) fit onto the west coast of America. Look up Jim Sears' Siberian Connection (below), SWEAT, or AusWUS.

Answer 7

Pangea was a temporary supercontinent. There were others before it that broke up. It's called the supercontinent cycle. see, for instance, http://en.wikipedia.org/wiki/Supercontinent_cycle.

There are a number of factors that come into play- plate tectonics and collisions from objects from space, for instance- that make the surface of the earth dynamic, not static. Factors in the forming of the earth such as magnetic variation would also lead to a planet that doesn't have equal distribution of matter over its entire surface.

Answer 8

Uhhh...you're forgetting the effects of asymmetric thermal convection AND the partial melting and fractionations that would have occurred. Also bear in mind, the crust was NOT like it is today, that is, mechanically strong. It went through a long phase of mechanical evolution before it could even support plate tectonics (before that, we had what is called: Ensialic re-mobilization, as with the Pan-African Orogenic cycles).

Pangea had to be created, but before even that, there was another super-Continent called Rodinia. After Rodinia was finally torn apart and PLATE tectonics became stable as a process, Pangea was slowly assembled. All of this took hundreds of millions of years.

Did this help???

Answer 9

While gravity is responsible for the generally spherical shape of the earth, there's a lit more going on than just that. The Earth is slightly oblong because of its rotational inertia, and in addition, the intense and complex interactions going on within the core are not neccessarily symmetric in effect.

Answer 10

A volume of water in many cases has a greater mass than an equal volume of soil. The remainder of the Earth still had water on it to balance the mass of Pangaea.