"Could the Meridiani Spherules be Surficial?" |
"Could the Meridiani Spherules be Surficial?" |
Jul 10 2007, 04:37 PM
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Junior Member Group: Members Posts: 42 Joined: 2-July 07 Member No.: 2646 |
I have been reading the response to the reponse to impact-surge linked by Dr Burt in post 170. The MER team objects to the impact-spherule explanation because " The spherules are dispersed nearly uniformly across all strata." I agree that is a valid criticism. It is very much like Dr. Burt's criticism of the MER team's hypothesis, that spherule distributions are not consistent with any conceivable ground-water movement regime that should have controled the development of concretions. I agree strongly with this point of Dr. Burt's as well. Neither theory does a good job of explaining the distribution of the spherules. Also, neither theory does a good job of explaining why the spherules do not apparently disturb the bedding.
There may be a solution in a possibilty that I now raise with some trepidation. I think that there is a chance that the spherules are superficial, and not an integral part of the Meridiani strata at all. This probably sounds crazy to many readers, but before rejecting it outright remember that science is at kind of an impasse on this and could use a new idea. If the spherules are superficial this would explain a number of puzzling observations. The layering at Homeplate and Meridiani is most simply explained by impact-surge. It is elegantly and inescapably explained by impact-surge. The impact-surge authors have also tried to explain the Meridiani spherules as part an impact event. If doubts are raised that the spherules are integral to the deposit, this would not in any way be inconsistent with the impact-surge origin of the layered structure. On the contrary, an objection to impact surge would be removed. I intend to start another thread under Opportunity to discuss this question. The first posting should be mine and should be an organized outline of how it might be possible that the spherules have been mis-interpreted as part of the Meridiani layered deposit. I am working on it. If anyone wants to start in on me with the obvious objections, do it here for now. Maybe Dr. Burt would like to respond. No matter what the details of spherule formation in an impact or spherule deposition in the impact sediments, the very uniform distributions that we see are troublingly unlikely. Random distributions are possible from explosive dispersal but less likely than some kind of clustering because of the rapidly changing conditions in the surge cloud. The more-uniform-than-random distributions of spherules on rock characterised by MER-team analysis cannot be explained by impact surge. |
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Jul 13 2007, 05:13 PM
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Junior Member Group: Members Posts: 42 Joined: 2-July 07 Member No.: 2646 |
Gray, Thanks for considering this. What I wrote is that Endurance shows no apparent extra spherules. The image you posted does very likely show spherules, and these are distributed thinly over the surface much as they are on the soil of the plains. What I think is missing at Endurance is any sign of spherules as scree deposits. We have not seen deposits of spherules anywhere that appear to have accumulated to a depth of more than one. On deeper soil, where trenching has been done the spherules are revealed to form a thin layer on the surface, though a few were seen at shallow depth in trench walls. In your image from Wop May's vicinity, we can be fairly sure that only a thin and partial layer of spherules is present because the bedrock is visible through the berries and soil. Here is another image from that same station that shows that bedrock is very near the surface.
http://marsrovers.jpl.nasa.gov/gallery/all...00P2415L5M1.JPG The spherules that have rolled from the crater walls could be hidden in some way but it would be reassuring to see them somewhere as a colluvial fan if they are descending the slopes. |
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