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Geomorphology of Cape York and Solander Point, Examining Opportunity's destination at Endeavour Crater
Stu
post Mar 31 2011, 03:48 PM
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Now that we're officially "on our way", I thought it might be useful to compare the size of some of the major features and landmarks on Cape York with Oppy, so here you go... You'll see some orange "spots" on the landscape when you zoom in on it. The dark pixels in the centre of the dot shows the size of Oppy. Not easy to see, I know, so I'll post a higher resolution version on my blog later...

Attached Image


As usual, this is intended to be a rough guide, not a definitive one.

Update: large version posted to my Twitpic account: http://twitpic.com/4fckki/full


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bgarlick
post Jul 19 2011, 06:19 PM
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While we are waiting to see Cape York, some Geology questions...

Cape York is lower than our present position (if it wasn't we would already see the peaks of Cape York above the horizon).

So... Will Cape York be covered in sulfate deposits and blueberries?

If 'Yes', then how come Cape York looks so distinctive from orbit with clear boundaries to the plains of Meridiani? If it was covered in sulfates and berries like everywhere else CY should appear as just a nondescript smooth bump.

if 'No', then how can you have Cape York be free of sulfates and berries if it is lower elevation than our current location? If Meridiani was created by a pool of evaporating water, then CY should have even more deposits on it than we see where we are now since it is at a lower elevation. Basically, how can you have an 'island' that is below the sea bed!? Presumably CY has not subsided... Note that from space CY shows different materials (such as clays) which implies that it may not be covered with sulfates and blueberries.

I am not sure what the answer is to this dilema. Does anyone have an explanation? One thought I had off the top of my head was that the sulfate deposits are from groundwater seepage (as has been proposed) with a geology sequence something like..

1) Endevour impact
2) vast deposits of basaltic sands introduced (which we see are underneath the thin sulfate deposits here)
3) sand gets blown around and out of Endevour crater so that around the rim there are sand deposts that are higher than the actual Endevour impact crater rim (ie higher than CY)
4) sand is also blown off CY or never even accumulated on it
5) water seepage comes to the surface, depositing sulfates, but water does not seep 'up' CY because it is too far for water to seep upwards and/or because it is made of impermiable rock instead of basaltic sands
6) water seep stops, sulfates erode leaving blueberry lag depost (except on CY )

So, I think it will be very interesting to see if CY has blueberries/sulfates on it or not....

Thoughts? huh.gif

-Ben-
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Julius
post Jul 19 2011, 06:32 PM
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I am no planetary geologist and therfore may not be knowledgable to answer such queries but I think that CY forms part of endeavour crater rim and thus represents material excavated from deeper layers on Mars which presumably contain the clays which predate the sulphates!
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centsworth_II
post Jul 19 2011, 06:56 PM
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QUOTE (Julius @ Jul 19 2011, 01:32 PM) *
... I think that CY forms part of endeavour crater rim and thus represents material excavated from deeper layers...
Yes, but at one point the sulphate layers covered Cape York. They have been eroded away so I would expect to find blueberries that eroded out of the sulphate layers on Cape York but I would expect little left of the Sulphate layers themselves. As for why the Meridiani plains leading up to Cape York are higher, I guess it's just a matter of differential erosion rates due to the prevailing winds over the topography of the crater.
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bgarlick
post Jul 19 2011, 07:14 PM
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QUOTE (centsworth_II @ Jul 19 2011, 10:56 AM) *
Yes, but at one point the sulphate layers covered Cape York. They have been eroded away so I would expect to find blueberries that eroded out of the sulphate layers on Cape York but I would expect little left of the Sulphate layers themselves.


This is quite plausable. In this case we should see a blueberry lag deposit directly on the clays (ie the sulfates are all gone in places). Blueberries over clays (and other CY rim materials) would look different than blueberries over sulfates & sands (which we are driving on) and would explain why CY is destinctive looking even though it is lower than the plains.
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marsophile
post Jul 19 2011, 08:22 PM
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There has been no mention of a hematite signature from Cape York. Wouldn't a blueberry lag deposit produce such a signature?
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Phil Stooke
post Jul 19 2011, 09:15 PM
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The CRISM composition data certainly don't seem to point to a blueberry layer on Cape York... but it's certainly legitimate to ask why not, if the whole area was covered with the plains material and it has eroded away. One possible explanation - blueberries were more common in some areas than in others, and this may be an area where they were not found to begin with. Test - look for blueberries in the plains immediately adjacent to the Cape.

Phil


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bgarlick
post Jul 19 2011, 11:00 PM
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QUOTE (Phil Stooke @ Jul 19 2011, 01:15 PM) *
The CRISM composition data certainly don't seem to point to a blueberry layer on Cape York...


If that is indeed the case, ie no berries/sulfates on CY while berries are [presumably] on the plains right around CY, then we have a head scratcher here and this might point more towards a groundwater source of the sulfate/hematite instead of an evaporated body of water (which would have had to have covered CY since CY is lower than the surrounding plains) as I proposed in my original post.

Note: I am not a Geologist, but my dad is... :-)

-Ben-
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marsophile
post Jul 19 2011, 11:20 PM
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QUOTE (bgarlick @ Jul 19 2011, 04:00 PM) *
(which would have had to have covered CY since CY is lower than the surrounding plains)


That might not follow. Flood waters pouring over a cliff will take the path of least resistance, and will avoid locally higher obstacles. It is only if the entire area was submerged that CY would necessarily have been covered.
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fredk
post Jul 19 2011, 11:58 PM
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QUOTE (Phil Stooke @ Jul 19 2011, 09:15 PM) *
it's certainly legitimate to ask why not, if the whole area was covered with the plains material and it has eroded away
Perhaps the berries rolled downhill into Endeavour, assisted by winds?

Moderators: perhaps this discussion should be moved to the "Geomorphology of Cape York" thread?
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serpens
post Jul 20 2011, 12:34 AM
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The topography inside Endeavour would seem to indicate that the sediments flowed into the crater from the NW. The contours also seem to indicate a slightly steeper channel just to the south of CY. It is pretty clear that the blueberries formed within the sediments and whether there was just groundwater or whether there was a surface water overlay would seem immaterial. Low profile notwithstanding the feature is fascinating, but concentrating on the geomorphology of Cape York in isolation rather than standing back and considering it in the context of Endeavour Crater as a whole could be a bit limiting.
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Gladstoner
post Jul 20 2011, 01:23 AM
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centsworth_II
post Jul 20 2011, 03:32 PM
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QUOTE (Phil Stooke @ Jul 19 2011, 05:15 PM) *
The CRISM composition data certainly don't seem to point to a blueberry layer on Cape York... ...Test - look for blueberries in the plains immediately adjacent to the Cape.
This Pancam from sol 2658, about 1200 meters from Cape York, shows plenty of berries.
Attached Image

Does CRISM really show no hematite signal from Cape York, or is it just that that is not where the focus of attention is at? Phyllosilicate and hydrated sulphates are the focus, but does that mean the hematite is not there or just not being talked about?

I think I will be more surprised to see few berries on Cape York than many. Just because I think The Cape was covered by the same berry containing layers that eroded away and left berries over the rest of Oppy's route. But maybe berry forming layers never did extend over Cape York. It will be interesting to see.
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centsworth_II
post Jul 20 2011, 03:59 PM
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QUOTE (Gladstoner @ Jul 19 2011, 09:23 PM) *
Two interpretations of the terraces of Cape York:
I hope you don't mind my fooling with your diagrams to better reflect the elevation between Cape York and the adjacent plains. (I'm sure Phil would do it if he had the time. laugh.gif )
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Gladstoner
post Jul 20 2011, 06:44 PM
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