I have not been idle the last couple of weeks; I’ve been reading more about the Hadean Era. (Well, working too.)
It seems there is some dispute about the climate of the Hadean Era, not surprisingly since there are no rocks at all left from it and reconstruction is necessarily theoretical.
The view I favored is that there was no standing water because (a) water and other volatiles were driven off by the collision between the Earth and the proto-Moon, and it would take hundreds of millions of years to restore the water via volcanic eruptions and comets; and (b) again thanks to the collision, the Earth’s surface would be very hot, maybe not molten, but so hot as to evaporate any water that did arrive. This is the Hot Earth view.
I find, however, that others argue the Cool Earth view that there were indeed oceans at this time; that even though the Earth was too hot for liquid water at present atmospheric pressures, the atmosphere was so dense that water could remain liquid far above the current surface boiling point (“Cool” is a relative term, obviously). I’m not clear on how such a dense carbon dioxide atmosphere could have disappeared, though. Did it become carbonate rocks? Or what? Or was this prior to the collision?
Obviously, I am not a geologist or a paleontologist, just looking longingly from the sidelines…
Anyway, I then found that as part of the Hot Earth view, once the Earth cooled down some, the water vapor from volcanoes and comets rained down, a constant torrential rain for a hundred million years that formed the oceans … wait. The oceans average less than three miles deep. Three miles is 190,080 inches. 190,080/100,000,000 is, um, 0.0019 inches per year. This is not a downpour. This is not a drizzle. This is not even *detectable*.
Okay, so there could still be a constant torrential rain for a hundred million years if we assume that the atmosphere cooled enough to allow water vapor to condense, but most of the Earth — particularly, I guess, the lower areas — was still hot enough to evaporate it. So rain falls on the high areas and low areas alike, evaporates immediately off the low areas (maybe even before it reaches the surface) and flows down off the high areas in great waterfalls that also evaporate … That’s a cool image, I think, if I can figure out how to create it.
There’s not going to be a lot of high ground left after this, though, is there? Erosion on steroids! About the only high ground will be freshly formed volcanoes and recent lava flows. Fortunately there will be lots of those. I also read about some cool craters in Idaho that formed by basalt lava trying to erupt through surface water, which sounds very like what you’d see on the early Earth as I imagine it. Not that such craters would last long because of the rain.
No wonder there are no rocks left from the Hadean.