Fiddling with volatiles

Take two brand-new mostly Earthlike planets.
Give one of them slightly less water than Earth, just enough for the oceans
to cover Earth's abyssal plains. Give the other one slightly more water than
Earth, enough such that the oceans would cover everything at lower altitude
than the Appalachian mountains.

So, what happens? The first thing that comes to mind about the wetter world
is that it would turn out mostly like Earth, but with very small continents
and enormous continental shelves with lots of islands. The drier world is
trickier, though. I expect that's still plenty of water to keep plate
tectonics going as usual. Would it end up with the same structure continents
have on Earth, with the high continental shelves dropping off relatively
steeply to the ocean depths below, just lacking differentiation between
continental mainland and shelves? Or would the edges be worn down so that
the continental highlands slope gently into vast shallow seas? Or something
else entirely?

-l.
------------------------------------
My inbox is a sacred shrine, none shall enter that are not worthy.


.

Relevant Pages