The End of Earthly Oceans - Ocean Worlds: The Story of Seas on Earth and Other Planets - page 210

surface of such an outwardly hostile surface. They would have to be
space visitors with time on their hands, for this would not be like the
present Earth, which is chemically and biologically dynamic enough
to immediately attract any passing interstellar travellers with a half-
decent set of sensors fitted to their spaceship. This inert, melted lump,
orbiting in the glare of a dying star, would not even attract a passing
glance.
By whichever type of greenhouse, the Earth will become a dry
planet.
The Earth after Oceans
An ocean-free Earth will not simply be the world we now know,
deprived of water. The deep, dry ocean basins will be covered in salt
crusts. The ocean trenches will represent the last deep seas of all,
made up of the dense brines the formerly abundant seawater had
become, and being filled with salt deposits some kilometres thick.
The now-exposed oceanic ridges will form land-based mountain
chains. For a while, they may still be stretching apart and erupting
floods of basalt. At the edge of the ocean basins, the continental slopes
may still be traversed by the degraded remains of the steep-sided
submarine canyons that used to carry dense floods and slurries of
sediment-laden water to the ocean floor. In the mountain chains that
fringe the continents, there may still, for a while, be volcanoes like
those of Popocatepetl and Chimborazo today intermittently and vio-
lently erupting steam- and gas-laden masses of ash and pumice high
into the atmosphere.
The familiar, long-lived tectonic activity of the Earth would likely
not persist for long. As the oceans disappear, the subducting plates
will no longer be lubricated by the seawater that they used to carry
with them. They will find their passage into the mantle more difficult
and friction-ridden. The upper regions of the mantle, too, deprived of