Rovers on Mars

I know how feels the touch of sedimentary rocks. With the subjective probability of 80%, the bedrock shown in the photo above is sedimentary.

well touch is not a sensation you are able to employ in this case satt.

we'll just have to keep speculating till we get some closer looks at the layering that you feel is sedimentary. If its a layered tuff we can both claim we won.

Tuff seems to be the most probable. It is a fairly hard stuff.

if you go to google and , in the images, type in "welded tuff" . If you imagine that volcanic dust over a long perios of time , keeps plopping down hot dust it forms a layered looking rock that , if you wind scour for many millenia, you could see how this gets sculpted.

Of course the mineral specks all appear to be from a single plume. I wonder if they printed a photo of this entire area to see what the pattern of vulcanism was.

Im still open to a mechanism that differentiated the minerals resulting from a meteorite hit. Then coupling that with wind erosion over a long time, you could develop the onion skin look. If you look at the earlier shot not all of the rocks appear layered , yet they all appear to have the same minerals andlight reflectance.

Wind erosion on tuff and that on granite (here irrelevant) yield totally different outlook. The layered-looking outcome of erosion presupposes a stratified structure in the original tuff.

There are several options open for genesis. Im not closed to any one , nor is there any visible evidence to bet the farm on one mode .
I m not as convinced as you because, if you look at the entire outcrop, only a portion of it looks like it has sedimentary features. The middle section looks blocky and massive, perhaps an area that hasnt been exposed to wind as long and there is no visable evidence of any layering there..

Agameticus granite and the Anorthosites of The Adirondacks are "taffy formed" granitic and dioritic rocks and there are a couple of exposures that have this very onion skin look .

Im still inclined to endorse tuufs but, im not 100% sure because of the blocky mid sections of the outcrop.

It looks as if spirit is back in action

CNN

Spirit Rover Drills Into First Mars Rock
By GREG RISLING

LOS ANGELES (AP) - Fresh from being given a clean bill of health, the Spirit rover drilled into its first rock on the surface of Mars, NASA scientists said Saturday.

``The rock gave us a lot of resistance,'' Gorevan said. ``We needed three hours to go this deep.''

Link

farmerman, any thoughts on what the resistance means, other than it's a hard rock?

the original TES on the orbiter showed lots of basaltic rocks, they did find olivine dust in the spoonfull they took up in Jan.
however (they named the rock that they drilled adirondack because of its shape not mineral content). The rig probably doesnt have much torque so a denser rock will cause major resistance, especially if its basaltic.Nor does the rig have a coolant for the bit end, so they cant push it or they pop the bortz on the button bit.
I need to get a general geol map of mars from USGS so I can interpret some of these local finds.
As you see, over on the other side of the planet , in a little crater, we may have some outcrops of welded tuffs, these would indicate a totally different kind of magma , because basaltic rocks dont form explosive volcanoes and welded tuffs only form in Mt ST helens types of volcanoes.

My impression of the rock Spirit has brushed is that it is very basalt like.

Hmm.. intriguing.
Glass?

The hunt has begun

Mars Rover Examines Bedrock for Water
By TIM MOLLOY

LOS ANGELES (AP) - NASA's Opportunity rover took microscopic images Sunday of a bedrock outcropping on the surface of Mars that scientists hope will answer questions about whether the rock could have formed in water.

The images will help scientists understand what the environment was like when the rock was formed, said Jim Erickson, deputy mission manager.

Link to article

those little bombs could be a type of TEPHRA (volcanic ejecta) that form in areas where the larger chunks accrete by falling into water. these are called accretionary lapilli , if they are an olivine or more acidic silicate they form whats known as Peles tears.

Or, more mundane, they could be just sand blasted chunks of glass. In a volcanic mix of ejecta, usually the
amorphous glasses are the most resistant to physical erosion.

these also could be the remains of the crystalline minerals after theyve eroded out of the rock by wind.
blasting. Rocks like porphyry

Although, Ive gotta admit, there sure are a lot of em.
The first pic showing the rounded thing in the middle. That was obviously subangular and its been eroded round , probably by sand blasting. Like the rocks in the Devils Racetrack, they probably get blown around so ultimately they get rounded more and more. Obviously there is a difference in the erosive properties of the balls and the bits thyre sitting on

That or one big mother strewn field of tektites,
I wish those People would put something in for scale and a corrected Munsell color scale

NEAT
Where did you get these shots Rosborne

From the "Raw Images" link on the Rovers Home Page: http://origin.mars5.jpl.nasa.gov/gallery/all

The images don't have captions yet, so we don't know what the professionals think of them, but maybe that's better; we get to make our own guesses before being "limited" by other opinions

The Sedimentary/Basaltic micrographs are posted below. What do you think of them? I find them very unusual; with "polished" edges over superheated, melted ... sediment? or Basalt? ... not sure yet...

My opinion is that they are once melted sedimentary layers with wind erosion and that not basalt.

WOW-Looksw like we have all got it right. Looks like the rocks contain those little rounded inclusions. There are 2 in the first pic , one thats free and one that is still eroding (its x center , and y about 60% down) its much smaller than the big bleb on the right . The second one is much more interesting. The "layers" look like the sections that protrude contain the little spheres. Heres a totally dumass idea, howabout were looking at multiple volcanic eruptions with the little spheres either setlled first in accordance with the mechanics of stratification (STOKES law) in fluids (a fluid is herein defined as a thick pyroclastic cloud , OR , if water was present, the pyroclastic cloud falls into water and settles out via density stratification . If you put a handfull of dirt into a bottle filled with water and then shake it up, the heavies settle first and smaller particles settle more slowly. Thats how we mostly see water lain strat and multiple pyroclastics made up of the tephra I was speaking about before.

This is close to what I do in my practice. I do exploration for lag deposits of titanium sands and rare earth sands. So, I owe satt a beer, looks like , right now, it may be air or water deposited sediments probably of volcanic origin..
The tools for the erosion seems to be those little sandy particles all over the first detail. I still wish wed have a scale. are those particles silt sized or sand sized?