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Thread: Asteroids modified the early Earth

  1. #1 Asteroids modified the early Earth 
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    Asteroid impacts significantly altered ancient Earth -- ScienceDaily

    During the 500 million years of the Hadean Period, from 4.5 to 4 billion years ago, Earth was struck by a number of very large asteroids. They must have melted the crust, and vaporised any liquid water. I wonder how much those early asteroids would have modified Earth so as to make it leave features measurable today? Would early life have had a chance, if it existed back then?


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    Anti-Crank AlexG's Avatar
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    During the Hadean Period most of the earth was still molten.


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    Alex

    That is not what the reference says. In fact, it says that there was liquid water on the surface, at least some of the time.
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    The Hadean /ˈhdiən/ is the first geologic eon of Earth and lies before the Archean. It began with the formation of the Earthabout 4.5 billion years ago and ended as defined by the ICS 4,000 million years ago.[1] The name "Hadean" comes from Hades, the ancient Greek god of the underworld, in reference to the "hellish" conditions on Earth at the time: the planet had just formed and was still very hot due to high volcanism, a partially molten surface and frequent collisions with other Solar System bodies. Thegeologist Preston Cloud coined the term in 1972, originally to label the period before the earliest-known rocks on Earth. W. Brian Harland later coined an almost synonymous term: the "Priscoan period". Other, older texts simply refer to the eon as the Pre-Archean.
    Hadean - Wikipedia, the free encyclopedia
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    Some of what is known is not so much known as the 'best possible scenario imagined' considering the information now available..
    Modeling of the most probable weighted against what we know. That the crustal surface of early Earth was resurfaced many times..The word 'Tumultuous' Springs to mind.. " BUT'' regardless of this, We can not with absolute precision state it with clarity.. That water itself might have arrived via comet collisions.. and that 'Life' might just have arrived here the same way.. These are arguments of extreme speculation and probability.. There is NO knowing.. just speculations.. It's all we have.
    ~ Just to make a clear and deliberate point; ~ These speculations of the very scientific method possible today are still being added to.
    The alternative thinking that a environment for humanity was created by intelligent design is NOT getting the door opened.
    Not that anyone has mentioned it.. Just clearing that point...
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    That's interesting.
    There is evidence that the earth has many craters, much more than imagined, in number by hundreds, and not all that large, but some are so large that we did not notice them until satellite images. They are up to 30 km wide, usually hidden by erosion, forests, ice and snow, ocean and sandy deserts.
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    Quote Originally Posted by skeptic View Post
    Asteroid impacts significantly altered ancient Earth -- ScienceDaily

    During the 500 million years of the Hadean Period, from 4.5 to 4 billion years ago, Earth was struck by a number of very large asteroids. They must have melted the crust, and vaporised any liquid water. I wonder how much those early asteroids would have modified Earth so as to make it leave features measurable today? Would early life have had a chance, if it existed back then?
    Yes. If only source past posts where this was handled beforehand by myself of other's research.

    The gist is that some parts of the globe would be relatively untouched, but all liquid water on the surface would be vaporized. It would, according to one documentary, vaporize the oceans at a rate of a meter every ten minutes, iirc, the atmosphere glowing at several thousand degrees in temperature (C or F is forgotten). But deeper extremophiles would persist perfectly happily under a very good insulating blanket of earth groundwater (which has to turn into steam, at large calorie loss, slowing the temperature gradient change). For example, post ice ages buried ice lasted in the steppes and temperate forests under the glacial til for several millennia, so good an insulator is rock. And in a couple of years superheated rain (about 150 C or more at those super pressures MB with all the oceans turned to steam) would reach the surface and come down rather quickly, it is said.

    The utterly massive rivers cascade down slopes to the ocean lowest floors, uncovering virgin buried microbes, extremophiles or not, with buckets raining down on just about every location an hour. In short, life would take a step backward, primitive as it was, but not be lost. In a hundred years, the road to progress would fill many a niche by those forms with the best advantages of the unique impact characteristics and then global topography. The microbes able to handle extreme temperatures would have a head start, but eventually all would cool down in parts and coincidentally water action uncover some coastal region down to undisturbed depths thermally at a point where those other less adapted microbes could survive and ultimately have the advantage over extremophiles. Some of this is my own assessment based upon readings, but you get the idea.

    Hope that helps. It pays to keep in mind that GCM of a steam atmosphere with insufficient insolation heat budget is extremely volatile and short lived, especially without a base source (like a thick, planet-wide molten body without bottom). The amount of liquid rock pooling is also irrelevant as an insulating crust would form within minutes, as does off of Hawaii, etc. Geothermal rates on Earth now are absolutely tiny compared to insolation from the sun. Here when it rains, it pours like Niagara in spades.
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