EAS 217 F20

Public Group active 3 weeks, 4 days ago

Global Impacts Video

  • This topic has 43 replies, 28 voices, and was last updated 1 month ago by .
Viewing 14 posts - 31 through 44 (of 44 total)
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  • #96587
    Steven Kidder
    Participant

    At any trench, it will be one plate going under the other… even if it’s at a triple junction.

    #96588
    Steven Kidder
    Participant

    20 meters/year??! whoa. Some things that would happen would be that the sea level would rise tremendously because the ocean crust would be warmer and less dense everywhere. So the continents would be flooded. Also, as you said, there would be a lot more volcanic gasses… my guess, probably still possible for a human to survive, but it would a very different place.

    #96589
    Steven Kidder
    Participant

    Yes there is a “supercontinent cycle”. So they have formed, and then break apart again eventually. As I understand, it has to do with all the heat that builds up under the supercontinent and causes rifting.

    #96590
    Steven Kidder
    Participant

    Please also see Amanda’s earlier post (she found the names and a link to more information about the earlier supercontinent.

    #96592
    Steven Kidder
    Participant

    yes.

    #96594
    Steven Kidder
    Participant

    It’s possible for the different boundaries to be subducted under a continent (like in this case, under North America. But things get warmer in the mantle, so the processes are different, so even if there is still motion apart or together it doesn’t make new sea floor, or volcanoes, etc.

    #96595
    Steven Kidder
    Participant

    Yes, the other Hawai islands do not have active volcanoes. The eruptions just stop happening… and there is actually a new island forming by volcanic eruption off the coast of the big island!

    To become “inactive” it just means the eruptions stop. So erosion and weathering take over. The rocks cool down (become more dense), so there is some elevation loss due to isostatic effect also. Eventually they become dense and eroded to the point they sink below sea level.

    #96596
    Steven Kidder
    Participant

    Subduction tends to happen when the sea floor is old and dense. The Atlantic sea floor isn’t super old… but also it is difficult to get subduction started. You have to overcome some resistance to get the process going. It’s a big question in geology, how that can happen.

    #96597
    Steven Kidder
    Participant

    Pangea is just the most recent one, so we have most information about it.

    #96599
    Steven Kidder
    Participant

    The continents form by many different processes, so they are more diverse. Usually at least though there is the old granites and gneisses and other “hard” rock. Then often one or more layers of sediment on top. The continents are many times older than the sea floor, so they have a more complicated history and structure.

    #96603
    Steven Kidder
    Participant

    The water is usually around a couple weight percent. It’s not a lot, but it makes a big difference!

    #96604
    Steven Kidder
    Participant

    Yes, the India-Asia collision will eventually stop. (Today we live in New York at the site of an old collision much like that one). And the placement of the continents keeps shifting, so yes, over time the arrangement will be quite different…

    #96605
    Steven Kidder
    Participant

    Yes, eventually Los Angeles will be off the west coast of Canada…

    #96624
    Steven Kidder
    Participant

    test reply

Viewing 14 posts - 31 through 44 (of 44 total)

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