Results 1 to 10 of 10

Thread: Are continents getting bigger?

  1. #1
    Join Date
    May 2004
    Posts
    1,766

    Are continents getting bigger?

    I read once that billions of years ago the only land was the island continent of Vaalbara.
    If so, does that mean the Earth’s land area is increasing?
    SHARKS (crossed out) MONGEESE (sic) WITH FRICKIN' LASER BEAMS ATTACHED TO THEIR HEADS

  2. #2
    Join Date
    Oct 2009
    Location
    a long way away
    Posts
    10,393
    These are normally described as supercontinents: https://en.wikipedia.org/wiki/Supercontinent

    They contain all the landmasses "pushed together". I don't know if the total land area has changed much, though.

  3. #3
    Join Date
    May 2013
    Location
    Central Virginia
    Posts
    1,709
    As sea levels rise I suspect they'll be getting smaller.

  4. #4
    Join Date
    Sep 2003
    Location
    The beautiful north coast (Ohio)
    Posts
    48,144
    From the University of Puerto Rico

    Table 1. Distribution of land areas of Earth in the last 750 million years. The global land coverage varied little within 10 to 30%, however, there where large transitions from South to North (Late Triassic, 220 Mya) and from East to West (Early Devonian, 400 Mya). Also, note the extreme clustering of over 95% of the land areas in one side of the planet (MFA) during Pangea (Middle Triassic, 240 Mya) and Rodinia (Precambrian, 750 Mya).
    The table gives the percent land mass and ocean over time, as well as distribution, such as between the northern hemisphere and the southern.
    At night the stars put on a show for free (Carole King)

    All moderation in purple - The rules

  5. #5
    Join Date
    Dec 2007
    Location
    Bend, Oregon
    Posts
    6,054
    From the perspective of the amount of continental crust vs oceanic crust, I would think the continents are getting bigger. Continental crust does not readily subduct so once formed, it tends to hang around. The oceanic crust gets recycled. Meanwhile, volcanic arcs are producing more continental crust. However, sea-level variation tends to flood or expose continents, and I think that accounts for the numbers in Swift's link above.

  6. #6
    Join Date
    Apr 2007
    Location
    Nowhere (middle)
    Posts
    35,629
    Continental crust erodes faster, doesn't it?
    "I'm planning to live forever. So far, that's working perfectly." Steven Wright

  7. #7
    Join Date
    Jan 2010
    Location
    Wisconsin USA
    Posts
    2,698
    Quote Originally Posted by Swift View Post
    From the University of Puerto Rico



    The table gives the percent land mass and ocean over time, as well as distribution, such as between the northern hemisphere and the southern.
    Surprising that 10 to 30 percent is called little. If we lost 5 percent of Florida, I would call that significant.
    The moment an instant lasted forever, we were destined for the leading edge of eternity.

  8. #8
    Join Date
    Dec 2007
    Location
    Bend, Oregon
    Posts
    6,054
    Quote Originally Posted by Noclevername View Post
    Continental crust erodes faster, doesn't it?
    Quite a bit faster. But the sediment that reaches the ocean forms the continental shelves, which are still part of the continental crust and not susceptible to subduction.

  9. #9
    Join Date
    Sep 2004
    Location
    South Carolina
    Posts
    1,592
    Quote Originally Posted by Tom Mazanec View Post
    I read once that billions of years ago the only land was the island continent of Vaalbara.
    If so, does that mean the Earth’s land area is increasing?
    I will hazard a guess that land area is not currently increasing, if by "land area" we are talking continental crustal plates. Billions of years ago the crust was being formed from solidified magma/lava, so I can see crustal plates forming up to a limit, then stopping.

    So, no, except for ocean levels going up and down, no more continental crustal plate increases.
    There is something fascinating about science. One gets such wholesale returns of conjecture out of such a trifling investment of fact.
    — Mark Twain, Life on the Mississippi (1883)

  10. #10
    Join Date
    Dec 2007
    Location
    Bend, Oregon
    Posts
    6,054
    Here's an article that discusses continental growth. The authors suggest that the bulk of the continental crust had been formed 3 billion years ago and the rate of growth has slowed since then. It's certainly not zero, though.

    http://rsta.royalsocietypublishing.o.../2132/20170403

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •