On the Road Again - volume 4 - Page 9

LWS--

Good, I'm _not_ going crazy.

See my note in "Feedback".

[link]

The last post on Page 8 is #151. The only post I see on Page 9, yours, is #161.

Let's see how many appear after I post this message...

--Bill

Now, this is strange. LWS's last message, the one I just repled to, was #161. After that reply was posted, LWS's msg disappeared and mine appeared. This is a reply to my last post.

Oh well.

--Bill

The missing posts were a consequence of yesterday's problems. Mark has fixed the problem.

Re the linear feature crossing the dunes:

Here is the sol 2123 ( Jan 13, 2010 ) L1 5x1 pan that includes the feature:

No right images were taken of the feature - or navcam images - so it is difficult to determine if this is a "real" feature or not - but I beleive that it is.

What I find maddening is that the "abnormal bedrock" near Marquette is *just* below the middle of the pan!

Nope. Don't have a clue what's happening inside the heads of the mission scientist.

NASA Mission News, a general rundown on what they found at Marquette:

[link]

In short:

"Marquette Island is a coarse-grained rock with a basalt composition. The coarseness indicates it cooled slowly from molten rock, allowing crystals time to grow. This composition suggests to geologists that it originated deep in the crust, not at the surface where it would cool quicker and have finer-grained texture."

--Bill

> ... about the roughness of the bedrock near the crater Conception...

Perhaps the roughness resulted when the bedrock was peppered by debris that accompanied the impact that produced Concepcion? (Assuming it is an impact crater.) This might either be smaller fragments that came with the impactor, or debris excavated by the impact.

Barsoomer, I was thinking more about the unevenness of the bedrock - not the debris on the surface. If you look at the 2131 3D pairs, there seem to me more sections raised or lowered than "average" and a number of "sinkhole"-like areas.

Perhaps the shockwave from the impact broke up the pavement and displaced it? The depressions don't look much like craters - secondary or otherwise.

The only thing planned for today for Oppy is the rest of a 360 navcam panorama. I guess we will have to wait until next week to see Concepcion up close. I wonder why there was no drive today?

Those banded dunes.

Once apon a time a man named Darwin described these banded dunes quite well I thought. Late at night it gets, “Er, cold.” These banes are nothing more than the condensation points at saturation.. Sometimes there is less and sometimes there is more moisture. The dunes act as a hydrometer, with past nights events left on the sides of the dunes

Let the boys scratch there heads. At least Dough aint in charge.

Fred,

Darwin’s Friend

Hi Fred,

Sands move with the wind and moisture, the heavier grains will find the lowest point, has to be said beautiful Strata on those dunes, says old Beach to me.

"And the Desert is that all will be"

What say you about Spirit? could if she lives be a Weather Station? Other tasks to do of course.

Kevin; The Mars geology section seems to have been forgotten so I posted some comments about the banded ripples and am glad you and Hort commented here.
IMO they represent a series of storm events which are recorded as synchronous bands that extend over what may be great distances.

RE: Reply 166 and sinkhole-like areas

Remember, on Sol 70 we discovered the "Anatolia troughs", linear features which are thought to be surface expressions of karst solution cavities in the soluble evaporite-sandstone along a joint system. So there is the strong suggestion of Karst topography in the region, and that would certainly include "sinkholes". That is why I start clucking whenever we get near a lineation.

The classic paper on this is:

POSSIBILITY OF KARST MORPHOLOGY ON THE MARTIAN SURFACE AT THE MERIDIANI LANDING
SITE FROM COMPARISON WITH TERRESTRIAL ANALOGS. Sz. Bérczi

Lunar and Planetary Science XXXVI (2005)
1051.pdf

I do need to do a literature search and see what work has been recently done on this.

--Bill

Bill; The uneven bedrock could also be due to the possibility we have traversed lower in the section where deeper rocks, below the planar beds, show the the effects of aeolian cross-bedding.

This may also account for the angular ejecta around the "new" crater.

We should soon be able to see.

Could be that, Ben. Or an older erosional surface that has been exhumed. Or any number of things. As I've said, craters are like roadcuts and we'll get a peek into the subsurface soon.

--Bill

Re, banded dunes/Meridiani.
Effects of liquid water and ice should not be discounted when considering origins of these formations. The ESA/Mars Express has found evidence of extensive masses of ice - glaciers - underlying much of the mid and polar latitudes of Mars.
The Meridiani Plain may once have been covered by a shallow lake or sea (a familiar idea). The finely stratified sediments, now partially exposed as 'pavement,' are evidence that this body of water was stable for a significant period, perhaps tens of thousands of years. The fine layers reveal at least seasonal/yearly variations in water-borne deposition.
A sudden episode of freezing and drying, perhaps accompanied by volcanic and other upheavals, marked the end of this putative sea. However, some or most of the water may have remained on-site in thin glacial form, followed by a period of climatic instability with many freeze/thaw cycles and cyclonic winds. During this time, the present 'dune' material (perhaps composed of shoreline sands) may have accumulated beneath, on top of and around the margins of the glacial ice-field. Periodic meltwater, moving beneath and within the ice, could then have sorted the materials into layered esker-forms, subsequently added-to and modified by aeolian forces. Presently, we may have a glimpse of this process in images such as [link] Note the exposed ice is perched atop a 'dune field.'
At Meridiani, cold and dryness gradually won-out; the ice melted or subliminated and was never replenished, leaving the scene much as it is today. The glacial ice would not have left a lasting impression on the soft, easily eroded lakebed sediments compared to, say, granite. A minor residual frost/thaw cycle, and wind, continue to modify the site, while in other areas of Mars vast deposits of water-ice await their turn in the sun.
Well, tea-time is over...

Jim Elder explains how the banded ripples in Meridiani may have formed in his discussion of wind-ripple deposits.
[link]

I don't know where my last post went but try this reference for banded ripples in Elders Wind-ripple deposits
[link]

sol 2133 Concepcion panorama. Fifty meters and closing.

Good overview of aeolian dunes.

Your first link is dead, the second is OK.

--Bill

Er, I have changed the name of the "fresh" crater ahead from "Conception" to Concepción ( without the accent mark ) in my comments here and Flickr comments.

After agonizing over the decision, I decided to change to the Spanish spelling to make my notation more consistent with the "official" naming convention.

It would have been an easier decision had the nickname of the ship ( Cagafuego ) been selected - but I suppose the powers that be couldn't do that. ( Maybe picking the name was a little joke? )

I'm with you on this 'ship' name Hort...Looks like Oppy can spend a lifetime at this crater!!! Powerful looking rocks showing!

yt
dx

Do you know of an aerial map to show its location with respect to this crater? I have tried for several hours to locate one but nothing seems to be on the net.

Perhaps this quote from this article is relivant to the planned drivearound of Concepcion:

The Mars Reconnaissance Orbiter (MRO) spacecraft has found clay-bearing rocks lying directly in the path ahead for the Mars rover Opportunity.

IF this crater is very young ( less than 1,000 years? ) then perhaps it has some exposed clay bearing rocks that have not yet had a chance to weather very much???

Oppy could be in this area for some time.

Although only 2 color images have been taken so far, thre are hints that there are many dark blocks that are not normal Meridiani Bedrock.