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How would look like Earth like planet with higher water cover

  1. Jul 24, 2011 #1
    I started to wonder how would look like a planet similar to the Earth but with ocean level higher by a kilometre or two. I know that it should make climate milder and more humid. I have however a geological question - would such water level affects continental plates?

    Should I assume:
    a) that the planet would look roughly like the Earth but with just higher water level (with big partially submerged continents)
    b) that would affect plate tectonic and cause some plates to be almost proportionally taller so difference between continental shelf and ocean depths would be higher
  2. jcsd
  3. Jul 24, 2011 #2


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    Two kilometres :bugeye: all that would be left of land is a few mountain ranges! This was the best picture I could find that annoyingly doesn't have much of a key but everything that's blue, green or yellow would be underwater in your model http://www.nasa.gov/multimedia/imagegallery/image_feature_1545.html

    EDIT: This would probably be better to post on the Earth sciences section rather than astronomy.
  4. Jul 24, 2011 #3
    I thought about a rocky exoplanet with similar composition. I can find myself a map and just make the modification. I was more interested whether higher sea level should affect plate tectonic or not.
  5. Jul 24, 2011 #4


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    The question invokes a complicated analysys that cannot be answered by a brief one line answer. I guess you are asking about what would the world look like after millions of years.
    The lighter continents (plates) float on a denser material below. Two plate meeting result in an uplift or crumpling of one plate, and we get mountain ranges. Erosion tries to break the mountain ranges down.

    So you have to ask:
    Would extra pressure on the sea floor by the extra water depth push the plates higher?
    Would the climate result in less or more erosion?
    Would there be more precipitaion? And more erosion.
    In a milder climate would freezing and melting of water, an important aspect of erosion, have less of an aspect?

    I do not think there is a simple answer.
  6. Jul 24, 2011 #5
    I mean mostly 1 question, that is the one that would make the most crucial difference.
  7. Jul 24, 2011 #6
    Water Worlds...

    I'd guess you're thinking of the hypothetical exo-planets dubbed 'water worlds', but not quite fully flooded...

    There's been times and areas on Earth that may give some clues.
    http://en.wikipedia.org/wiki/Sea_level (YMMV ;-)
    "While the Mediterranean was forming during the past 100 million years, the average ocean level was generally 200 metres above current levels."

    That does not allow for tidal and storm-surge ranges.

    Also, glacial cycles seem to have swung 'our' sea levels from plus 70 metres to minus 150 metres, give or take some isostasis. The low-stand was enough to expose Behring Straits, a vast area off SE Asia aka 'Sunda-land' and much of area between UK and Europe aka 'Doggerland'...

    At the other extreme, tectonic rather than Milkanovich, there's the 'Western Interior Seaway'
    ... With wide, open water between the 'Gulf', Hudson Bay and Alaska...

    My guess is that you may get 'Ring of Fire' mountain ranges, hot-spot island chains per Iceland and Hawaii, plus flood-basalt plateaus, eg per Deccan Traps and Columbia area

    A lot of 'land map' may depend on the existence of a 'coral reef' analog to stabilize sand-banks and volcanic shores...
    Last edited: Jul 24, 2011
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