Did our planet - Earth - arise from violent collision of asteroids? Despite many theories, computer simulations
and geologic observations that support such a scenario - scientists begin to have serious doubts about this theory.
If the Earth arose from the collision of asteroids, its composition should resemble that of meteoroids, the small
particles that break off from asteroids.
According to standard theories of planetary evolution, the Earth should harbor a reservoir of mantle somewhere
in its interior that has a low ratio of uranium to lead, to match the composition of meteorites.
However, such a reservoir has yet to be discovered - a detail that leaves Earth's origins hazy.
Now researchers in MIT's Department of Earth, Atmospheric and Planetary Sciences have identified a "hidden flux" of
material in the Earth's mantle that would make the planet's overall composition much more similar to that of meteorites.
This reservoir likely takes the form of extremely dense, lead-laden rocks that crystallize beneath island arcs,
strings of volcanoes that rise up at the boundary of tectonic plates.
As two massive plates push against each other, one plate subducts, or slides, under the other, pushing material from
the crust down into the mantle. At the same time, molten material from the mantle rises up to the crust, and is ejected
via volcanoes onto the Earth's surface.
According to the MIT researchers' observations and calculations, however, up to 70 percent of this rising magma
crystallizes into dense rock - dropping, leadlike, back into the mantle, where it remains relatively undisturbed.
The lead-heavy flux, they say, puts the composition of the Earth's mantle on a par with that of meteorites.
"Now that we know the composition of this flux, we can calculate that there's tons of this stuff dropping down from
the base of the crust into the mantle, so it is likely an important reservoir," says Oliver Jagoutz, an
assistant professor of geology at MIT.
"This has a lot of implications for understanding how the Earth evolved through history."
Lake In France Turns Red
This year, we have encountered the color red in places where we don't expect to see it. A while back the strange appearance
of Azov Sea stunned residents who saw how the water had turned red. The red rocks in China have also puzzled scientists for a long time.
Now, a lake in Southern France has also suddenly turned red.
An Incredible Geological Phenomena
Earth is an amazing planet and our nature is full of wonders. We have previously written about incredible singing plants.
This time we would like to focus our readers' attention on another amazing geological phenomena, namely so-called growing stones.
It is difficult to image that stones can really grow, but these stones seem to be alive!
Yangtze River In China Turns Red
We have seen on a couple of occassions how lakes and seas have suddenly turned red.
In August a lake in Southern France unexpectedly changed color and shortly before that the strange appearance of
Azov Sea stunned residents who saw how the water had turned red....