Did Ancient Glaciers Shape Mars' Surface? Deposits Found By Space Probe Hint Five-Mile-Deep Valley Was Carved By Ice

By Rob Waugh

PUBLISHED: 10:25 EST, 30 March 2012 | UPDATED: 10:25 EST, 30 March 2012

Dailymail

Huge glaciers might once have lurched through the 1,800-mile long Valles Marineris valleys on Mars.

The glaciers would have carried sulphur and dust from Martian volcanoes as they carved the five-mile-deep trough on the surface of the planet.

The new theory could explain deposits of sediment which were first seen by the Mariner 9 probe 40 years ago and which have puzzled scientists ever since.

‘Icy weathering might be a major part of the geologic story on Mars,’ said PSI Research Scientist Joseph Michalski, ‘The planet has been in a cold, frozen state for a long time.

‘In the distant past, it was also cold, but volcanoes were much more active, periodically pumping huge amounts of sulfur into the atmosphere, which could have ultimately ended up trapped within ice alongside plentiful dust.’

Inside the canyon are vast mounds of layered sediments of enigmatic origins which have puzzled scientists for decades. 

A number of recent publications have suggested that the deposits were formed by water upwelling, where subsurface water breaches the surface during occasional upwelling events.

But the Michalski’s team points out that the deposits are ‘draped’ over the canyon walls – and for the groundwater scenario to be true, the entire canyon would have had to be filled with sulphur.

For the deposits to have been left by water would have required more sulphur that would be available on the whole of Mars.

As an alternative, Michalski and Niles suggest that the ILDs formed from massive, dusty ice deposits that once filled much of the canyon.

Such a scenario is consistent with the size, topographic configuration of the deposits, and with their mineralogy, which suggests weathering in an acidic, water-limited environment.

‘Icy weathering should be much more important than the Earth because Mars lacks liquid surface water to buffer chemical processes,’ Michalski said. ‘As was pointed out by the great mineralogist Roger Burns more than 20 years ago, icy systems should become very acidic on Mars.’

‘We are of the opinion that Mars has been cold and dry for quite a long time, and that during that time, the various cycles of dust deposition, ice precipitation and sublimation, and sulfur outgassing can explain quite a bit of the surface geology.

‘Even so, the hypotheses are not without certain complications and uncertainties. It is our hope that more scientists will be begin to test these ideas.’

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