[X] My Assistant

[Bill Harris]

'Tis a big mystery what the mineralogy is here. I said this was going to be an interesting stop...

Here is a HiRISE color (IRB, I think) of this part of the traverse, the "central" part of Cape York: ESP_021892_1775_COLOR. You can flip thru Tesheiner's Route Maps to locate where we are (and were). Our current area is just right of center and the "double peak" in the lower left is where Oppy was on or about Sol-2746.

--Bill

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[StephenGFX]

Here is a HiRISE color (IRB, I think) of this part of the traverse, the "central" part of Cape York: ESP_021892_1775_COLOR. You can flip thru Tesheiner's Route Maps to locate where we are (and were)....
--Bill

I have combined Tesh's latest map with your posted image:

:

[ngunn]

Great posts everybody. I was wondering, now that we've seen this outcrop from several angles, how confident are folks feeling that it is indeed an exposure of everted Endeavour rim stuff that has remained in situ since the impact? How far can it be followed along the strike direction?

[fredk]

Wow, this flat light-toned outcrop is really looking like something new to me:
http://qt.exploratorium.edu/mars/opportuni...5M1.JPG?sol3071
But I thought there was something familiar about it... then it occured to me:

[Stu]

Looks at wall...

"Who did that plastering job? Right bunch of cowboys, by the looks of it..."

[Bill Harris]

then it occured to me...

aeolian erosion is scalable?

Wonderful lithologies here. I'd like to know more about those (lower in the section) outcrops we saw on the way here (Sol-3051-ish). And there appears to be several interesting exposures all the way to the top of Shoemaker Ridge.

So much to see.

I have combined Tesh's latest map with your posted image:

On the image files I use here I generally have several "annotation" overlays so that the main image doesn't get cluttered. I can view any, all or none of the layers.

--Bill

[ngunn]

"Who did that plastering job?

Actually I was thinking it looks quite clay-like. Anybody else?

[dvandorn]

It does sort of look like a form of mudstone, doesn't it?

Actually, of course, it's just the remnants of the concrete floor of the old thoat pen that used to stand here...

-the other Doug

[walfy]

The "plastering job" in 3D:

[Don1]

I think it looks a lot like dried plaster/gypsum/calcium sulphate. This from Wikipedia:

"The hemihydrate (CaSO4·~0.5H2O) is better known as plaster of Paris, while the dihydrate (CaSO4·2H2O) occurs naturally as gypsum."

On a related topic, I found this conference paper on simulated wind erosion of soft sedimetary rocks. Some of the pictures in the paper look like what the rover is seeing on Mars. In particular the rocks developed a finely laminated look, and also they formed pedestals or fins.

Rossman-Wilson-Shieber 2012 LPSC paper

[serpens]

It does sort of look like a form of mudstone, doesn't it?

The pamcam ratios seem to imply that this (unnamed?) target is primarily basaltic mud with teeny tiny sparkly bits. My bet is that this is a localised mudstone formed from material eroding from higher up CY - clay rich possibly, but how could we tell? I think we saw mudstone (shaley siltstone) around ‘Cortez’, probably from material eroded from the shoemaker formation. Still, this is a really nice place for Oppy to soak up the rays while brushing and then getting some APXS information. Unfortunately we will probably have to await the next LPSC to get detail.
IMO the spherule layer is more interesting. Glass is comparatively vulnerable to erosion and the apparent differential erosion here will probably tell us something in hindsight. Is this a deposit arising from the Endeavour impact or was it a pre-existing uplift? The apparent dip could possibly imply so. If pre-existing was it an original placement, or the result of erosion/transportation and deposition with strong lithification of the matrix. Since the Miyamoto ejecta blanket in this area would have been hundreds of metres thick and massive channels cut this ejecta blanket to the south all options seem equally likely. My head hurts.

[PDP8E]

here is my take on the 'mud floor' here at CY

[mhoward]

It's labelled "Whitewater Lake".

[stevesliva]

here is my take on the 'mud floor' here at CY

Looks like desert varnish.

[Bill Harris]

This new unit is indeed interesting. I think that the unusual appearance is due to aeolian erosion on a material with different characteristics than what we have become accustomed to. For the time being I'm thinking of it as a "fine-grained material with unknown affinitities". What intrigues me is the pattern of fractures. I see that the IDD is setting up on it so perhaps we'll be getting MIs soon.

I see that it has been named "Whitewater Lake". Appropriate? I've had a soft spot for the Whiterock Formation for the last 30 years and I'm glad they didn't adopt _that_ name.

As we've discussed before, Serpens, this area is going to prove to be horrendously complex. No doubt there will be much arm-waving and pacing of the floor going around. I've even started thinking of the spherules as "spherules of unknown affinities".

--Bill