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View Full Version : Maybe Water Didn't Make the Gullies on Mars



Fraser
2006-Mar-21, 04:22 AM
SUMMARY: It was only a few years that researchers announced the discovery of gullies on Mars. Here on Earth, gullies like this are formed when water flows quickly down a hill, and erodes the soil. Unfortunately, there might be another explanation for the Martian version - since similar gullies have now been seen on the Moon as well. It's possible that the gullies are formed completely dry, when micrometeorites strike the side of a crater wall and trigger a landslide.

View full article (http://www.universetoday.com/am/publish/recent_mars_gullies.html)
What do you think about this story? post your comments below.

antoniseb
2006-Mar-21, 01:17 PM
Mars has water. Mars had water. Mars has always been dry. Mars has frozen seas and lakes. Water wasn't required to make watery features... Martian geological (martilogical?) history is supporting a lot of opposing theories which carry roughly equal weight in the press. It shouldn't be too long (a few years to decades) before some of these can be put to rest.

Blob
2006-Mar-21, 02:33 PM
Hum,
this is of course ancient news...(ie, new planet, Pluto, found!) ;)

It is known that the dust and `sand` on Mars acts differently than on earth.
The dust is a lot more mobile.
The process of `sand streams` (even `waterfalls`!) had been suggested before as the agent of the smaller gullies. It does not run counter to the idea of the `real` water formed formations that are seen there,
(in the same way that the sand sculpted formations on Earths deserts exclude the existence of water here).

Jerry
2006-Mar-22, 04:41 PM
Hum,
this is of course ancient news...(ie, new planet, Pluto, found!) ;)

It is known that the dust and `sand` on Mars acts differently than on earth.
The dust is a lot more mobile.
The process of `sand streams` (even `waterfalls`!) had been suggested before as the agent of the smaller gullies. It does not run counter to the idea of the `real` water formed formations that are seen there,
(in the same way that the sand sculpted formations on Earths deserts exclude the existence of water here).
The dust is more mobile? Why? Grain shape? Less gravity? Less moisture holding it together? smaller mean particle size? Less static cling? Are the gullies of Mars more like alluvial flow patterns?

aurora
2006-Mar-22, 05:12 PM
A lot of researchers make the mistake (in my opinion) of making an observation about a particular location or type of feature on Mars, and then extrapolating their conclusion to the entire planet.

Mars, albeit very cold and at first glance very constant geologically, is a very complex place with a long complex history. I am certain there are gullies on Mars that were caused by slides, others by slumps, others by lava flows, others by impacts partially melting material, and others by liquid melted either by sunshine due to a changing climate and axial tilt or by tectonic activity (such as the relationship between the Tharsis uplift and Valles Marineris).

The rovers are discovering a number of complex and novel geologic features, and they are just covering a tiny percentage of the planet.