Re: Mountains
- From: " George" <george@xxxxxxxxxxxxxxxxxxxxx>
- Date: Tue, 13 Sep 2005 02:30:13 GMT
"jonathan" <write@xxxxxxxxxxxxx> wrote in message
news:AhqVe.461$Ve1.95@xxxxxxxxxxxxxxxxxxxxxxxxx
>
> "Jo Schaper" <joschapern4ospam@xxxxxxxxxxxxxxxxx> wrote in message
> news:11huudadae6vo2a@xxxxxxxxxxxxxxxxxxxxx
>> jonathan wrote:
>>
>> > If you'll notice, the dunes are finely laminated, as are almost
>> > all the Meridiani dunes. This means the wind didn't simply
>> > blow the dust in and leave it as we see it. It means the
>> > sand dunes were buried. Then excavated by water at the bottom
>> > of a lake/sea. And later modified by wind
>> > http://www.windows.ucar.edu/tour/link=/earth/geology/sed_dunes.html
>> >
>> > Which is why they are so complex. These Meridiani dunes are not
>> > your typical wind blown dunes. And since these dunes are still
>> > clay-like, not rocks, it means they are not terribly old.
>> >
>>
>> Suggest you do some googling on the term 'loess', and you may find earth
>> analogs to finely laminated windblown silt deposits.
>
>
> Of course those laminated dunes were laid down is such a way.
> The link I posted is clearly about wind blown dunes.
>
> That was not my point at all, it was that these dunes are
> now shaped into large magnitude parallel ripples which are
> ...water formed dunes. In other words the wind blown
> sand dunes were later covered by water and buried, then exposed
> again to the wind as we see now.
Incorrect. There are many instances of wind-blown sand dunes forming in
such parallel ripples. You really should do your homework before you post
such nonsense in a geology newsgroup, Johnny.
> And googling loess also shows such wind blown dunes are
> generally associated with glaciers and in ages measured in
> thousands of years. Which was my other point, they are young.
(Heavy sigh). So you are suggesting that because such features that have
been found on earth are young that the ones on Mars are also young? What
have you been smoking lately, Johnny?
> My point is that the dunes show Meridiani has gone through
> alternating dry wet periods in it's recent, not geologic, history.
> My point holds.
Your point is without merit, as usual. In addtion to what I've pointed out
above, do note that not all parallel sand dunes are associated with
glaciers or glacial features. In fact, there are large tracks of parallel
sand dunes in most of the world's large deserts. One in particular comes
to mind; the Simpson desert, in Australia:
http://www.cameltreks.com.au/images/Simpson-Desert-Stripes-1_ed.jpg
These are certainly NOT associatedf with either glaciers or bodies of
water.
NEXT!
.
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