Victoria's Innards, Your last chance to speculate before we really see it Options

[Bill Harris]

> won't dare step into a geologist's boots, but here's an image which shows that the scalloping of VC is not unique:

Ah, that crater has a form uniquely different than Victoria's, and since you found another scalloped crater rim, it is not unusual. Ergo, unique but not too unusual.

--Bill

[Pando]

I won't dare step into a geologist's boots, but here's an image which shows that the scalloping of VC is not unique:
Unfortunately I do not know what the source is, only that I believe it came from this forum a couple of years ago and I recall it was located in the vicinity of Meridiani. Hopefully this "alternate Vicky" could inspire the geo-minded to understand the processes involved.

Hmm, that reminds me... I posted (as 'youremi') 2-1/2 years ago (exactly!!) at the other forum about some craters I've found in Meridiani here:
http://www.marsroverblog.com/discuss-11596...ally-weird.html

There are links to MSSS for them as well, including this bad boy:

http://marsoweb.nas.nasa.gov/landingsites/...02-01143_05.jpg

It appears that larger impacts are punching thru some sort of evaporite layer which ends at some discrete depth. Interesting... Then again, it could be an illusion since the sand starts getting accumulated at the bottom, and we may be seeing the borderline where the sandy slope is starting, which is presumably not a steep as the rocky inner slope?? If I remember right, I think these craters are some 20+ km south-east from Oppy's current location.

[fredk]

Thanks, Pando. Judging from the filename and creation date it was probably in your post that I found that image.

[Pando]

"Buck Galaxy"? Not another nom-de-modem of Pando?

LoL (haven't heard that one mentioned since the good ol' BBS days...!)
No, thankfully not... This guy apparently hotlinked an attachment from this board and... well... Doug wouldn't like it too much

[Bill Harris]

Uh, yes, your post "over there" a couple of years ago. The place does have a unique character, no?

Your examples are why my hope and dream is that the mission would be able to continue the traverse down-section. This locale does have a wonderfully complex stratigraphy.

--Bill

[ngunn]

Hmm, that reminds me... I posted (as 'youremi') 2-1/2 years ago (exactly!!) at the other forum about some craters I've found in Meridiani here:
http://www.marsroverblog.com/discuss-11596...ally-weird.html

There are links to MSSS for them as well, including this bad boy:

http://marsoweb.nas.nasa.gov/landingsites/...02-01143_05.jpg

It appears that larger impacts are punching thru some sort of evaporite layer which ends at some discrete depth. Interesting... Then again, it could be an illusion since the sand starts getting accumulated at the bottom, and we may be seeing the borderline where the sandy slope is starting, which is presumably not a steep as the rocky inner slope?? If I remember right, I think these craters are some 20+ km south-east from Oppy's current location.

Thanks for posting that Pando. Post 44 inside your first link describes exactly the mechanism I have been suggesting for the formation of Victoria. That's reassuring, but it's still only in blogland. Does anyone know if it has appeared, even as a possibility, in the scientific literature?

[edstrick]

Than's for re-posting a pic of the double layered crater. I'd also posted a copy of a cropped image of that crater, maybe a year ago.

The essential point that these craters make is that the evaporite layers are separated by a very well defined layer of near-zero-strength material, probably of some significant thickness....I'd speculate quite a few meters, at least.

A small impact would crater the top layer, a bigger one would punch into the soft-stuff underneath and maybe have some disturbed rubble in a flattish bottom. A still bigger one punches a second crater in the deeper evaporite layer. In all likelyhood, the greater the thickness of the soft-stuff layer, the more defined and wider the bench is in the crater, though there will be some effect of crater size, too.

My impression is that the double-layer crater punched through the second evaporite layer (I'm SURE it's not a fresh lava flow or anything), into MORE soft-stuff underneath. That may well be what we're seeing at Victoria, but without a second evaporite layer in this region. Access to the soft-stuff layer may be pretty nearly impossible without a much more capable rover, and one equipped with some serious drilling or at least trenching capability.

[ngunn]

Access to the soft-stuff layer may be pretty nearly impossible without a much more capable rover, and one equipped with some serious drilling or at least trenching capability.

Not necessarily. Some of the 'soft stuff' would have been present in the ejecta. Of course it may subsequently have dried out and turned into something much like an evaporite, but I'm sure those clever geologists will be able to distinguish that from fragments of the original pre-impact evaporite layer.

[edstrick]

I think most of the local soft-stuff has blown away with most of the ejecta layer (except for blueberries), and been replaced with the basaltic sand that I think has actually drifted across Meridiani from outside sources. A petrology lab would have lots of fun with samples, and MSL might do a pretty good job, but MER gets only hand-lens black and white info on the fine bits samples are made of, the other instruments just average large (square centimeters) areas.

[Gray]

The latest images of Victoria appear to show that most of the bays are covered by drift that seems to be continuous with the sediments in the bottom of the crater. Do you think the sediments in the bays are drifting in from the plains surrounding the crater or is some of the sediment in the bays being transported up and out of the crater through the bays?

A secondary question: if there is a layer of poorly consolidated sediment beneath the rim, then how much of the sediment in the floor of the crater is from the crater itself?

[ngunn]

The latest images of Victoria appear to show that most of the bays are covered by drift that seems to be continuous with the sediments in the bottom of the crater. Do you think the sediments in the bays are drifting in from the plains surrounding the crater or is some of the sediment in the bays being transported up and out of the crater through the bays?

A secondary question: if there is a layer of poorly consolidated sediment beneath the rim, then how much of the sediment in the floor of the crater is from the crater itself?

I'd guess the inward and outward flows of drift material are about equal, or else it would either fill up or empty out completely. Of course that says nothing at all about what these rates actually are, or how they compare with the age of Victoria, which is what we'd need to know to answer your secondary question.

[gregp1962]

I'm confused. Are we looking over the near rim and seeing the far rim? It looks so close

http://qt.exploratorium.edu/mars/opportuni...CNP0666L0M1.JPG

[djellison]

You have it right. I know it's confusing, but basically, the view is quite similar to Endurance, just scaled up

Dogu

[Pando]

Dogu?

[MarkL]

Has anyone considered the possibility that Victoria could be a caldera rather than a crater? Seems a bit wild I'm sure but this is a very unusual crater. It is highly eroded yet still has a distinct bowl shape. I find it so bizarre. I wish some genius would explain its morphology. The degree of erosion is incredible given the fact the form of the crater is well preserved. It must be very very soft stuff those blueberries are in, evaporite or whatever because the wimpy Martian wind can blow it away.