Hi, I'm really enjoying this exchange. Very interesting information. And I will be the first to admit that there's a strong possibility these things ARE non-living minerals, possibly like crystals that grow differently on Mars than they do here. But I'm not convinced. By coincidence, on Sunday I was talking to a Utah Geological Survey geologist, Mark Milligan, for for a story. He happened to mention Great Salt Lake sand, which which Bill Biesele talked about in his posting, which is oolitic sand. Mark and I were looking at a wall on the Avenues, loaded with lots of different minerals the builder had picked up around the state. One of these nodules built into the wall was an oncolite, the fossilized remains of a colony of algae. The colony had formed around something, possibly a rock, and the accretion happened the same way as oolitic sand. The growth rings of this ancient colony went all the way around the rock, layer after layer. "It's rolling around in the tide or something, that's why it's spherical," he said. An oncolite differs from a stromatolite because of that fact. Stromatolites are fossil algal colonies that were fastened to the shallow sea floor and grew upward, layer after layer. They would not be round. My impression is that rolling around in the sediment is how oolitic spheres are formed, and that they are round. But these strange things on Mars, whatever they are, are not round. Where one is nearly falling out of a rock ledge, as one is shown in an earlier picture, it is flat on the bottom (with interesting details). But when we see them from top, they're rounded on top. Where they stick up, they _appear_ to be somewhat conical, though that could be just a distortion caused by taking close-up stereo photos of a rounded object. They don't seem to have formed by rolling around in some medium and acquiring material, as I think oolitic minerals do. If you look at some recent photos by Opportunity, you can see that one almost certainly pushed up through overlying sediment. In other words, it grew, it did not accumulate by rolling around. That's not to say it isn't some sort of mineral nodule that grows like a crystal, but it is strange. It's also possible that the layer that appears pushed up around it actually formed after the sphere and sort of washed up against it, then hardened; or that the sphere proteted adjacent areas from erosion of some kind. But to me the more likely explanation is that the sphere grew up through the layer, pushing parts aside as it did. The remains of this pushed-up material are standing on end around it. Here are URL for two views that make a great stereo pair so you can really see them in three dimensions. The "blueberry" on the left seems to have pushed up, erupting through the formation. You will also note, when you view it in 3D, that like a great many other "blueberries" it has groves that curve from the top toward the bottom. Maybe there's another mineralogical explanation for the growth of a nodule like this, but I don't know what it is. I don't think it's an oolite, however. A pair of photos that show that a sphere pushed up through an overlying layer: http://marsrovers.jpl.nasa.gov/gallery/all/1/m/041/1M131833478EFF0574P2952M2... http://marsrovers.jpl.nasa.gov/gallery/all/1/m/041/1M131833559EFF0574P2951M2... Thanks, Joe

site for oolitic limestone

http://www.science.ubc.ca/~geol202/sed/sili/oolites.html

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That's it? Somebody sends you a photo of earthly spheres and you give up the whole campaign? Come on, Joe, keep carrying that torch! What about your "roots" & percieved growth? Oh, ye of little faith... ;) --- Joe Bauman <bau@desnews.com> wrote:

Rob Ratkwski sent me a great photo of "moqui balls" or moqui marbles that he collected near Kanab. I have to admit, there is an amazing similarity, though they are on a different scale (the Mars "blueberries" are much smaller). I gather some scientists believe these were formed by natural processes involving groundwater and iron. So maybe what I have been so excited about is nothing more than another indication of water on irony old Mars. -- Best wishes, Joe

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If the Mars marbles are similar to Moqui marbles or Entrada berries it could be bigger news than if they are oolites. The marbles/berries form in sediments around decaying organic detritus. (At least if my poor memory serves me). More local ties between geology and astronomy: One of the lead geologists for the current Mars missions wrote a paper (MS thesis?) on Upheaval Dome in Canyonlands as a meteorite impact site; coauthor was Gene Shoemaker (a geologist by training, got into astronomy from studying the geology of Meteor Crater). One of the professors at the U, Dr. Marjorie Chan, wrote a paper saying the deformed bedding in the Entrada Formation north of Moab was caused by the Upheaval Dome impact. She also calculated the orbital period of the moon during the PreCambrian by studying the rocks near Storm Mountain in Big Cottonwood Canyon. That was a fine article on geology in a rock wall. It must be fun job to be paid to talk to scientists in as many fields as possible. The geology in a wall piece is similar to Gene Shoemaker's story of discovering (recognizing) a big meteorite impact crater in Germany by looking at the rocks in the walls of a cathedral. Bill Biesele On Mar 9, 2004, at 10:39 AM, Joe Bauman wrote:

Rob Ratkwski sent me a great photo of "moqui balls" or moqui marbles that he collected near Kanab. I have to admit, there is an amazing similarity, though they are on a different scale (the Mars "blueberries" are much smaller). I gather some scientists believe these were formed by natural processes involving groundwater and iron. So maybe what I have been so excited about is nothing more than another indication of water on irony old Mars. -- Best wishes, Joe

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Thanks Bill! It is fun most of the time, but I'm looking forward anxiously to retirement -- in exactly four years and one month I will be 62, able to retire. (I think I have to work through the end of the month, so the actual date will be about May 1, 2008, but I still use my birthday, the 10th, as a monthly marker when I mentally flip the calendar over one page.) There are so many things I want to do that I haven't had the time for, with astronomy high on the list, that I should be busy and happy without this work. Best wishes, Joe

That was a fine article on geology in a rock wall. It must be fun job to be paid to talk to scientists in as many fields as possible.

The geology in a wall piece is similar to Gene Shoemaker's story of discovering (recognizing) a big meteorite impact crater in Germany by looking at the rocks in the walls of a cathedral.

Bill Biesele