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UCLA Scientist Discovers Plate Tectonics On Mars
Reader SternisheFan links to a press release at UCLA, and excerpts from it another bit of Mars news: "For years, many scientists had thought that plate tectonics existed nowhere in our solar system but on Earth. Now, a UCLA scientist has discovered that the geological phenomenon, which involves the movement of huge crustal plates beneath a planet's surface, also exists on Mars. 'Mars is at a primitive stage of plate tectonics. It gives us a glimpse of how the early Earth may have looked and may help us understand how plate tectonics began on Earth,' said An Yin, a UCLA professor of Earth and space sciences and the sole author of the new research."
I always found it odd that Mars' southern hemisphere would be so much higher than the northern one. This discovery means it might be simply a supercontinent that will be, in spite of its size, a transient[*] feature.
I'd like to hop on a time machine, go forward 200 years and read up a book on the geology of Mars. I wonder if they'll name previous continents (assuming they can be determined) by a system that uses names from famous Mars-related stories. The first bunch of continents named after features in the John Carter of Mars stories, another bunch taken straight from Bradbury's Martian Chronicles, et cetera.
[*] In a geological time scale, of course.
"Trust me - I know what I'm doing."
- Sledge Hammer
Actually, I've usually heard Olympus Mons mentioned as evidence against plate techtonics. It was created by a hot-spot, like the Hawaiian islands, but the reason it's so big is that the plates aren't moving, so the hot-spot stayed in the same place the whole time. If the Pacific plate weren't moving, there would only be one Hawaiian island, and it would be much bigger!
The most likely scenarios is Venus got steamed over by some large SOB.
Seriously, look at its parameters,
Sidereal rotation period -243.018 5 day (Retrograde)
Axial tilt 177.3 degrees
http://en.wikipedia.org/wiki/Venus
and for Mars,
Sidereal rotation period 24.622 9 h
Axial tilt 25.19degrees
So, Mars is like Earth. Kind of "normal". The day takes about same amount of time and tilt is similar. Mars is kind of like a twin of Earth. And since there is evidence for water on Mars in the past (back when it had a magnetic field), tectonic plates are kind of expected.
Of course *now*, that tectonic activity may have stopped. There is no evidence for recent tectonic activity on Mars. Mars lost its water and atmosphere to space, mainly due to collapsed magnetic field. The planet is just too small to carry on the "dynamo" going for 4,000,000,000 years. 2,000,000,000 years ago, Mars could be with liquid water and maybe even breathable atmosphere.
As to Venus, well, its axis tilt is fucked. It is spinning the "wrong way" (opposite of other planets). Something big rolled over Venus long time ago, bit enough to make it spin the other way. Maybe it never recovered from that event. And since Venus now has no tectonic activity (observed via a Magellan)
http://en.wikipedia.org/wiki/Magellan_probe
it can't remove its CO2 from atmosphere, and well, that is causing problems. Like being the hottest place in the solar system. Current understand of tectonic plates require water to "push" one planet beneath another. On Venus, there is evidence that internal pressure is causing some parts to go up and some down, but there is insufficient height differential to force one plate under another and no water to fill in the holes and move the "low" areas lower. So you end up with no tectonic plates.
As to an example of another planet that got reamed by something large, it would be Uranus. It has axis tilt of about 90 degrees