The Naked Scientists

The Naked Scientists Forum

Author Topic: Any theories about most anitpodes of continents being oceans and vice versa?  (Read 5530 times)

DiscoverDave

  • Guest
This shows the antipodes of the Earth and that most antipodes are also opposites regarding surface types (dry land versus ocean).  I don't believe in some many "coincidences".  The law of averages says that this shouldn't be.  Any suggestions why this should be?
« Last Edit: 25/12/2009 15:06:44 by DiscoverDave »


 

Offline Geoman69

  • Jr. Member
  • **
  • Posts: 14
    • View Profile
I don't have enough information to work with on this one.  What percentage of continental antipodes plot to dry land?  Remember that ~71% of the surface is ocean, so one would expect only ~ 29% of continental antipodes to plot to dry land.

I can't think of any geophysical mechanism that would explain some kind of "?antipodal fractionation?", but it is interesting to think about. 
 

Offline JimBob

  • Global Moderator
  • Neilep Level Member
  • *****
  • Posts: 6564
  • Thanked: 7 times
  • Moderator
    • View Profile
There is a theory that the earth has had a "lopsided" history due to the collision that formed the moon.

As I am one absolutely lazy person, I am going to quote verbatum Wikipedeia:

http://en.wikipedia.org/wiki/History_of_the_Earth#The_giant_impact

"A rare characteristic of our planet is its large natural satellite, the Moon. During the Apollo program, rocks from the Moon's surface were brought back to Earth. Radiometric dating of these rocks has shown the Moon to be 4527 ± 10 million years old,[12] about 30 to 55 million years younger than other bodies in the solar system.[13] Another special feature is the relatively low density of the Moon, which must mean it does not have a large metallic core, like all other terrestrial bodies in the solar system. In fact, the Moon has a bulk composition closely resembling the Earth's mantle and crust together, without the Earth's core. This has led to the giant impact hypothesis, the idea that the Moon was formed during a giant impact of the proto-Earth with another protoplanet. The Moon formed by accretion of the material blown off the mantles of the proto-Earth and impactor.[14]

"The impactor, sometimes named Theia, is thought to have been a little smaller than the current planet Mars. It could have formed by accretion of matter about 150 million kilometres from both the Sun and Earth, at their fourth or fifth Lagrangian point. Its orbit may have been stable at first, but destabilized as Theia's mass increased due to accretion of more and more matter. Theia oscillated in larger and larger orbits around the Lagrangian point until it finally collided with Earth an estimated 4.533 Ga.[15]

"Models show that when an impactor this size struck the proto-Earth at a low angle and relatively low speed (8–20 km/sec), a lot of material from the mantles (and proto-crusts) of the proto-Earth and the impactor was ejected into space, where much of it stayed in orbit around the Earth. This material would eventually form the Moon. However, the metallic cores of the impactor would have sunk through the Earth's mantle to fuse with the Earth's core, depleting the Moon of metallic material.[16] The giant impact hypothesis thus explains the Moon's abnormal composition.[17] The ejecta in orbit around the Earth could have condensed into a single body within a couple of weeks. Under the influence of its own gravity, the ejected material became a more spherical body: the Moon.[18]

"The radiometric ages show the Earth existed already for at least 10 million years before the impact, enough time to allow for differentiation of the Earth's primitive mantle and core. Then, when the impact occurred, only material from the mantle was ejected, leaving the Earth's core of heavy siderophile elements untouched.

"The impact had some important consequences for the young Earth. It released a gigantic amount of energy, causing both the Earth and Moon to be completely molten. Immediately after the impact, the Earth's mantle was vigorously convecting, the surface was a large magma ocean. Due to the enormous amount of energy released, the planet's first atmosphere must have been completely blown off.[19] The impact is also thought to have changed Earth’s axis to produce the large 23.5° axial tilt that is responsible for Earth’s seasons (a simple, ideal model of the planets’ origins would have axial tilts of 0° with no recognizable seasons). It may also have sped up Earth’s rotation."

See also http://en.wikipedia.org/wiki/Giant_impact_hypothesis and http://en.wikipedia.org/wiki/Moon#Origin_and_geologic_evolution 

What this means is that the earth, through most of it's history, has wobbled on its axis. WHY?

SOME scientist believe that it is because of fundamental mass distribution of the crust due to the impact 4.5 billion years ago. In this theory, continental drift is just the result of the attempt of the earth to redistribute mass.

I can't see that being the case. The ratio of the thickness of the crust to the radius of the earth 50 km to 6,378 km (50:6,370) 0.0078492935635792778649921507064364 to 1.

NOW, if you weigh 300 pounds (112 kg) the thickness of your skin over your stomach would be MANY orders of magnitude GREATER than the thickness of the earths crust. That is why I believe that this theory is NOT a good one. Relatively speaking, the mass of the earth's crust is just too small to effect the distribution of the continents on the crust. There is some other cause as the continents just move back and forth with respect to each other. North America-Europe have collided twice in the last 1 ± billion years: the 1250-980, million years ago, and the Pennsylvanian-Permian collision that formed the Appalachians 350-300, million years ago.

It is to me the distribution of continents is an unexplained phenomenon.
 
 
« Last Edit: 27/12/2009 17:11:37 by JimBob »
 

Offline RD

  • Neilep Level Member
  • ******
  • Posts: 8124
  • Thanked: 53 times
    • View Profile
 

Offline JimBob

  • Global Moderator
  • Neilep Level Member
  • *****
  • Posts: 6564
  • Thanked: 7 times
  • Moderator
    • View Profile
« Last Edit: 27/12/2009 20:25:48 by JimBob »
 

Offline geo driver

  • Sr. Member
  • ****
  • Posts: 419
  • if you have a smile, share it
    • View Profile
like a convayer belt new rock comes up ald gets recycled. perhaps
 

The Naked Scientists Forum


 

SMF 2.0.10 | SMF © 2015, Simple Machines
SMFAds for Free Forums