Teaching Rhys and Hannah about finding evidence of water on Mars through the rocks seen there by analogy with stones on Beach at Bognor Regis

Sometimes I find that our own planet can give me insights into the work of NASA and WAS when they send probes and landers elsewhere. This was the case yesterday when Rhys, Hannah and I walked on the beach here at Bognor Regis.

Recently, we have been told that the Curiosity rover on Mars has found evidence of water on the planet and this stimulated a discussion on how evidence of water in the past can be found on a dry planet today. Admittedly, recent evidence proves there is still water on Mars now but our discussion was around demonstrating previous water.

We noticed that the stones on the beach at Bognor Regis had a number of features:

1. They were of numerous colours suggesting different mineral contents. Assuming that rock’s in a particular area tend to be composed of similar minerals, this indicates that some process has bought together small rock’s  (stones) from different areasxand only process we know of to do that on Earth is liquid flow – water although on Titan this can be methane/methane and on Pluto it is nitrogen. However, the temperature on Mars would support water flow preferentially.

2. The stones on the beach were rounded indicating a process that bashes the edges off – on Earth this is due to rolling as they are carried along by the sea and washed ashore. On Mars round blueberries demonstrate a similar process has occurred in the past.

3. The stones were separated by size depending on where they were on the beach. Location of stones indicates processes that took them the. On Mars, rounded stones are found in depressed areas consistent with previous river beds. Dry now, these previously carried water.

Andy

 

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