Mount everest is the floor of an ancient ocean.

The floor of the modern sea is basalt from the mid ocean ridges, millions of years old in some places. Basalt has olivine as a principal component. These seafloor originated basalts occur on land in places and are much older, like in Nova Scotia. It still has its olivine, even there. Obvious conclusion - olivine is stable in the presence of water. Corollary - they're wrong about olivine stability, and have made incorrect extrapolations from one experiment (I read that one), ground up basalt + acid + air with oxygen = not stable. Google for basalt olivine composition.

I have been strongly influenced by the recent report of Sulfate layers deep within the VM. Keep in mind that Basalts can erupt sub-aqueously, as on Earth. The Malin pictures of very uniform thickness layers in the VM also has had a strong influence on my theories. This is most probably due to cyclic sedimentation, and there were several thousand feet of these layers in one picture. Volcanism seldom produces many layers of near equal thickness.

How can you state that there is no room for an ocean in Mars past? How thick of a stratigraphic sequence is exposed, compared to the planet's diameter? Attempts at trying to date basement rocks from [a distribution of] buried craters.... that must be pretty darn speculative. Sounds about as far out as some of my ideas! I like it, but how can they see under all that rock??? (sarcasm)