The oldest mountains on Earth: the Barberton Belt?

Discussion in 'Earth Science' started by valich, Oct 31, 2005.

  1. valich Registered Senior Member

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    Most scientist agree that the Barberton Greenstone Belt in eastern Africa is the oldest mountain range on Earth (3.5 billion years old), and it is said that it is possible to deduce the entire geological history of the Earth by examining these uprising mountains in this ancient sea floor area.

    The Guiana Highlands in South America are thought to be the earth's oldest surface (2 billion years old): it includes a large mountain plateau.

    Then there is the Medicine Mountain on Wyoming were they have dated rocks to 2-3 billion years ago.

    However, on top of all this we have the 3.8 billion year old 25 mile long band of zircon crystal rocks embedded in the Isua crust in Greenland! (http://www.findarticles.com/p/articles/mi_m1134/is_4_113/ai_n6026419

    A lot of people in the U.S. think that the Appalachians were among the oldest mountains formed. Although they are very impressive, stretching from the Eastern U.S. to Canada, Labrador, Scotland and down to Morocco, they were formed only about 680 mya during the formation of Pangaea. But we now know that Pannotia preceded Pangea and another supercontinent called Rodinia formed 1,100 mya.

    So if we have evidence of mountains at 3.8 bya, we must have had a land mass on Earth even way before then? This seems to contest the theory that the Earth was totally underwater until 3.8 bya, and that we still don't know?
     
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  3. Facial Valued Senior Member

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    Sorry, can you explicate again why this early existence of mountains correlates to the existence of land?

    I question this because there are undersea mountains too.
     
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  5. valich Registered Senior Member

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    Of course we have undersea mountains, but if you read my post more closely, I said that we have evidence of an above sea level land mass 3.8 bya. I am not questioning or conscerned with undersea mountains. We also have the first evidence of microorganisms (probably cyanobacteria) from the Western Coast of Australia at 3.86 bya. We must of had an above sea-level land mass before this time. Does anyone know?
     
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  7. valich Registered Senior Member

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    According to the latest edition of Scientific American it now seems that we have evidence of an Earth land mass dating back to at least 4.4 bya. Tho oldest intact rock is found in Canada and dates back to 4 bya; however, zircon crystals found in Western Australia date back to 4.4 bya. Because these crystals have a high oxygen isotope level, only found in cooler areas than magma, it is thought they that they were formed under liquid water and low temperature conditions on the surface of the Earth. This pushes the age of Earth's known initial landmass back by "at least 400 million years earlier than the oldest known existing sedimentary rocks, those at Isua, Greenland [3.8 bya]". So the Earth may have cooled in merely 100 million years and formed a landmass or landmasses as early as 4.4 bya.
    "A Cool Early Earth," by Jogn W. Valley, Scientific American, Oct. 2005, pp. 59-63.
     

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