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HindustanTimes Sun,23 Nov 2014

Science

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Water was flowing on Mars 200,000 years ago
PTI
London, April 28, 2014
First Published: 10:29 IST(28/4/2014)
Last Updated: 10:34 IST(28/4/2014)

A very young crater on Mars has shown evidence that liquid water existed on the red planet as recently as 200,000 years ago, according to a new research.

"We have discovered a very young crater in the southern mid-latitudes of Mars that shows evidence of liquid water in Mars' recent past," said Andreas Johnsson at the University of Gothenburg.

The southern hemisphere of Mars is home to a crater that contains very well-preserved gullies and debris flow deposits, researchers said.

The geomorphological attributes of these landforms provide evidence that they were formed by the action of liquid water in geologically recent time, they said.

When sediment on a slope becomes saturated with water, the mixture may become too heavy to remain in place, leading to a flow of debris and water as a single-phase unit. This is called a debris flow.

Debris flows on Earth often cause significant material destruction and even human casualties, when they occur in built-up areas. During a debris flow, a mixture of stones, gravel, clay and water moves rapidly down a slope.

When the sediment subsequently stops, it displays characteristic surface features such as lobate deposits and paired levees along flow channels.

It is these landforms that Johnsson has identified on Mars. The research group has been able to compare the landforms on Mars with known debris flows on Svalbard with the aid of aerial photography and field studies.

The debris flows on Mars provide evidence that liquid water has been present in the region.

"Our fieldwork on Svalbard confirmed our interpretation of the Martian deposits. What surprised us was that the crater in which these debris flows have formed is so young," said Johnsson.

Crater statistics allowed Andreas Johnsson and his co-authors to determine that the age of the crater to be approximately 200,000 years. This means that the crater was formed long after the most recent proposed ice age on Mars, which ended around 400,000 years ago.

"Gullies are common on Mars, but the ones which have been studied previously are older, and the sediments where they have formed are associated with the most recent ice age. Our study crater on Mars is far too young to have been influenced by the conditions that were prevalent then," Johnsson said.

"This suggests that the meltwater-related processes that formed these deposits have been exceptionally effective also in more recent times," Johnsson said.

The study crater is situated in the mid-latitudes of Mars' southern hemisphere, superposed on what is known as the rampart ejecta of a nearby larger crater.

A rampart ejecta display a "flowerlike" form around the host crater, and scientists have interpreted this as being the result of an impact in wet or ice-rich ground.

The study was published in the journal Icarus.


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