An hour on line? I envy you your free time, Rodger. On Aug 29, 2012 1:39 PM, "Rodger C. Fry" <rcfry@comcast.net> wrote:
I have spent the past hour studying in detail the first image that Patrick referenced herein. It is a great shot and tells much. He is very correct that it did make me react like Pavlov's dog! As a geologist, the first thing that comes to mind when viewing a sequence of bedded strata is what is the method of genesis. Bedded sequences can be prevalent in both volcanic and sedimentary sequences. An inspection of the bedding and the thin-continuous layers appears to be sedimentary rather than of volcanic origin. With this being determined, I have to ask myself, in what environment did the sedimentary sequence form.
Sedimentary beds can be deposited in a broad range of environments from Aeolian (wind derived), Alluvial (gravity or water transported and is a deposition of mass wasting), Fluvial (river deposited sediment), Lacustrine (Lake deposits) and Marine (deposited below sea level). Each of these depositional environments has characteristic tale-tale signs that can be used to determine the general depositional environment that the sediment was deposited in.
With Mars present lack of water, one cannot overlook the possibility that sedimentary sequences are Aeolian. Sediments deposited in this environment can have beds that are laterally continuous but within these beds, strong cross-stratification should be present. I can't see any evidence of cross-stratification and even with the detail of this image, I would expect to see some of this if it were Aeolian. I therefore believe that these beds are not deposited by wind. This suggests that water came into play.
The strata are much too laterally continuous to be alluvial/colluvial which demonstrate strong lenticularity (lens shaped beds in cross-section. I feel that it is fairly easy to eliminate alluvial/colluvial deposition other than the uppermost beds just below the skyine (with some small knolls overlying them) which might be alluvial/colluvial (based on cross-cutting relationship with underlying sediment).
Most of the sedimentary sequence has beds that show strong lateral continuity and locally, some subtle lenticularity. This is very consistent with either lacustrine or fluvial deposition. I feel there is a better than even chance that the sediments were deposited in a river or lake or combination of the two. The sedimentary signature is also consistent with marine deposition but this couldn't be determined without a much closer review. Based on 40+ years in studying fluvial,lacustrine and marine deposition in deltaic environments, I see a more compelling argument to call this sequence fluvial/lacustrine.
It appears that the sedimentary beds are dipping slightly toward Curiosity as well as to the right. If this is taken toward Sharp peak this dip is what I would expect because the beds would be uplifted by the rebound that occurred after the meteor hit that formed Gale crater and dip away from Sharp peak. If you look at the image 1/3 of the way from the left and 1/3 of the way from the top, you see a rounded knoll that has, in descending order, a light colored sequence underlain by a darker sequence that is thick and then two light sequences separated by a thin dark sequence. This same pattern exists in the background on the slope in the upper left. If I were there, I would want to see if these are the same sequences and if they are, are their position on the terrain the result of dipping beds or do we have faulting behind the knoll and in front of the aforementioned slope.
Without a doubt, Curiosity and the JPL team have their work cut out for them. From what I see here, a wealth of information is about to come forth and we have just begun to explore.
I can't wait to see more.
Rodger C. Fry
-----Original Message----- From: utah-astronomy-bounces@mailman.xmission.com [mailto:utah-astronomy-bounces@mailman.xmission.com] On Behalf Of Patrick Wiggins Sent: Wednesday, August 29, 2012 3:58 AM To: utah astronomy listserve utah astronomy Subject: [Utah-astronomy] Favorites so far
I'm watching the replay of yesterday's NASA news conference and I saw these images that I'm calling my favorites so far: http://mars.jpl.nasa.gov/msl/images/PIA16105u_malin04MAINIMAGE-br2.jpg http://mars.jpl.nasa.gov/msl/images/PIA16104_malin03m100focus-br2.jpg
Somehow I get the feeling that geologists (Rodger?) will salivate when they see them. :)
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