Violent geology on Venus

While there's growing evidence suggesting that Venus indeed had oceans of water briefly during its prehistory, it is presently a dessicated planet that's very unlike Earth.

Most striking is Venus' lack of plate tectonics-the means by which carbon compounds are recycled through crustal rocks. Without such a dynamic geo mechanism, Venus has been dubbed the "runaway greenhouse effect" planet. It became the poster child for global warming proponents, thanks to its excessive natural amounts of atmospheric carbon dioxide.

There are also many volcanoes visible on the surface of Venus-in fact, several of these carbon-dioxide belching mountains appear to be active today although there's no definitive proof.

Between the Mariner II and Magellan probes to Venus, spanning the years 1962 to 1994, researchers such as astronomer David Grinspoon of the Denver Museum of Nature and Science reasoned that some bizarre global catastrophe resurfaced the planet every few million years-this all due to the large number of young volcanic peaks and the small number of old asteroid impact structures (fewer than 1,000 impact craters have been found).

It was clear that impacts had occurred on Venus, but some planetwide event apparently erased the ancient impact craters within a short span of geologic time.

Thus, a planetwide volcanic event, on an apocalyptic scale never seen before in our solar system, was proposed as the reason for Venus' "fresh" resurfacing.

Expanding this theory, astronomers then concluded that nothing much happened on Venus after the planetary upheaval.

Now, planetary geologists Timothy Bond and Mike Warner of Imperial College in the U.K. have shown that the global volcanic catastrophe on Venus probably never took place.

Bond and Warner looked at NASA's Magellan spacecraft data from the 1990s and found that that the distribution of old impact craters on Venus was random; the ancient craters were nearly pristine, untouched by anything resembling a planet-scale cataclysm. Bond and Warner rejected the accepted theory as simply too fantastic to take seriously.

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