A recent PBS program showed showed that Venus has a very “average” distribution of craters.
One scientist theorized that possibly Venus had undergone a catastrophic event in its past that might have liquified its surface.
His premise is that occasionally, every couple hundred million years or so, the surface of Venus breaks completely up, and sinks back into its molten interior.
Then the surface cools, and a new round of “average” bombardment occurs for the next couple hundred thousand millennia.
Isn’t Venus tectonically inert? (Let’s try that again.) Doesn’t Venus show an absence of tectonic activity? If that’s the case, then it would seem that there is no reason that the distribution would be “average,” since crust is not continually being created/destroyed.
The program did a fair job of showing both sides–that is the scientists in the catastrophism/something-else camp (although the other “V” word never came up).
And, no, I am not a Velikovskite–but neither of the views presented in the program had anything better than Venus’ having been cue-balled in the distant past by some renegade asteroid, either.
Maybe I missed something in the presentation, but the central mystery that was brought out was the “average” distribution of craters. That was apparently a big surprise.
There’s not a lot of cratering going on in the solar system anymore, Mjollnir. Even in geologic time frames. Most of the orbital debris that led to craters has been swept up over time. The “seas” on the face of the moon, for example, are relatively uncratered even though they are old and the processes that caused them are long extinct.
Venus also has a very thick, hot atmosphere which shields the surface and, I suppose, also drives erosive weather processes, although I don’t know anything about weather on Venus.
So any craters on Venus are presumably quite old and their relative presence or absence is due to happenings long ago.
“The departure of the church-going element had induced a more humanitarian atmosphere.”
Dorothy L. Sayers Clouds of Witness
Given that it is so similar in size and composition to Earth, one could speculate that the interior of Venus produces just as much heat as the interior of Earth. On Earth, a great deal of that heat is dissipated by tectonic activity, pushing crustal plates around, volcanoes, and suchlike. There is no evidence of this sort of activity on Venus.
I propose, then, that the crust of Venus is not fractured into the thin plates that characterize Earth, but is rather thicker and less conductive to heat. The heat from inside Venus thus builds up until the entire crust melts, then radiates the heat away and solidifies again.
I believe we will have to wait until we can get a deep-drilling rig on the surface before we can answer any question about the age of the Venerian surface.
Don’t forget that Velikovsky was talking about Venus being formed in the extremely recent past (3000 years ago or so, IIRC). When scientists talk about ‘recent’ cratering, they are talking about timespans in the millions of years.
If Venus were only a few thousand years old, it would have almost no craters at all. How many big meteorites have hit the Earth in that time?
The radar maps of Venus show a lot of volcanic features. But without a recycling process like a subduction trench, the Venusian basalt would just continually pile higher and deeper on whatever was the original proto surface of the planet. This seems unlikely. At least eustatic changes caused by the weight of the erupted material would deform the crust into a basin. I do not recall if any of the Venusian volcanic features line up like Earth’s spreading centers. But I appeal to the Great Occam and his Razor by speculating that all planets with internal heat and subsurface convection currents produce spreading centers, subduction zones and moving plates. Thus the Venusian crust is being recycled not catastrophically but gradually and continually. Any meteor craters would be randomly spread over a relatively blank, or at least frequently erased, slate. None of Earth’s oceanic crust is over 200 million years. Only on Earth’s continents do we find the remnants of really old cratering which would slant the statistic distribution. With regards to the universality of plate tectonics, my personal opinion is that the Valle Marineris (sp?) on Mars is a enormous rift valley, not caused by water (though some might have flowed in later)but by plate movements.