[X] My Assistant

[RNeuhaus]

From today, Oppy will start to head toward the Victoria Crater which is about 500 meters away. The drive would take about one month (that is 15 soles of driven with an average of 33 meters/sol, the other 15 soles would be for other purposes or restrictive soles).

The surface around Victoria Annulus, I seems it won't be as smooth as the way between Eagle and Endurance craters but the surface would have no uniform or parallel wave of sand and dust in small size of ripple. See Phil's Victoria Annulus partial map, Tesheiner's one Victoria Crater picture

Otherwise, the surface might have ripples smaller and alike to the ones of El Dorado, on the skirt south side of Columbia Hill. Besides, the Anuulus has no outcrops except to around of few small mini-craters.

This is a change of morphology of surface around the Victoria Annulus. What does it explain about this developing kind of surface of sand? Its extension is just around the inside of Victoria's ray of ejection. That is coincidence. Around that has no bigger ripples as the outside of Annulus.

The explanation would be that around annulus has smoother rock or outcrop surface, no blocks which had not helped to build ripples by the winds. Other factor, I am not sure, is that the slope from the border of Annulus to crater is positive (going up by few meters), then this might be another factor not to build ripples. I have seen that anywhere in the desert that have a slopes does not have any ripples but only flat surface.

Any debate about why the Victoria Annulus does not look like ripples as the outside of Annulus.

Rodolfo

[Gray]

I think Bill might be on the right track. Look again at Nirgal's colorized image of the pebbles:

http://mitglied.lycos.de/user73289/misc/op...24pan_col_d.jpg

Many of the larger grains have a shape that looks like a Hershey's kiss. Some have suggested that they might be ventifacts. But it would take winds blowing equally from every direction to sculpt a grain that way. Unlikely IMO. Bill's suggestion that they may be formed by a melt/impact process makes more sense to me at this point.

One of the grains at the lower left-hand edge of Nirgal's image provides some tantalizing evidence for this idea. The grain is cut by the edge of the image, but you can see that there is a smaller grain (blueberry) contained it a larger grain. It looks as if part of the larger grain has wrapped around the smaller grain.

I'm envisioning a process like this: the meteor strikes the surface of Mars and in the process melts many of the silicate minerals in the crust (it could be a lower basalt or the basalt sands). Molten blobs fly through the air assuming a streamlined, rain-drop shape. The strike the surface while still partly molten. This flattens the bottom but they still retain a streamlined shape in the upper part.
If the grains fell, while partly molten on a surface which was already littered with the smaller blueberries. (A process Bill has already proposed). The under side of the "Hershey's kiss" grain would have the smaller blueberry imbedded in it. That partial view of a grain with the embedded blueberry might be evidence for this.

- gray

[dvandorn]

I think Bill might be on the right track. Look again at Nirgal's colorized image of the pebbles:

http://mitglied.lycos.de/user73289/misc/op...24pan_col_d.jpg

Yep. Please note that in the attached image, there are really four different size populations in the objects we see.

The finest particles are dust-sized, and are consistent with windblown dust particles or the aeolian erosional remnants of local larger bodies which have been worn down by local winds. These particles form the primary portion of the soil matrix at this site, and they resemble (a lot) the fine dust portion of the soil that we've been seeing all along.

The next largest size of body resemble, in size and general shape, the blueberries we've seen ever since Eagle. They seem to be more broken up -- some appear to have started out spherical but have been partially or completely shattered. But these look like the blueberries we've been seeing.

The next largest size of body we see are what Bill is calling tektitic. Most of them seem to have a conical shape, and while the linked image doesn't show this well, many of them have a small depression, pit or hole at the apex of the cone. One would be tempted to say, with a quick glance at the image, "Oh, yeah, those are blueberries." But if you compare their size (larger than the blueberries we've seen before) and their presence in the same soil with smaller bodies that far more closely resemble the blueberries we've seen before, you can see that these are different types of bodies. The conical (or teardrop) shapes seem unlikely to be ventifacts because of the very small size of the bodies and because they appear to have been evenly shaped into regular cones all along their circumference.

There is one larger sized body type in this image, as well -- a more rough-edged pebbly kind of stone that someone remarked (sorry, I don't remember who originally noted this) looks rather like chert or flint. These have multiple fracture planes that form their surfaces, and are significantly larger than either the blueberries or the tektitic droplets.

These four different types of bodies seem to be fairly well mixed in the soil here. But they are definitely all different in appearance, and I would imagine they are all different morphologically.

I'm about 80% convinced that the conical or teardrop shaped objects are some form of impact melt. I don't necessarily have an explanation for why they don't look glassy. I suspect it's a matter of either their initial composition or, more specifically, the volatiles content of the original melt that is responsible for this appearance.

-the other Doug