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Home Plate Speculations, Get it in now, before we know the truth!
dvandorn
post Jan 25 2006, 04:10 PM
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Down in the Front Page Stories board, Phillip asked what all of us UMSF types think Home Plate might be made of and how it was formed. He actually wants Jim Bell's speculations, but asked for UMSF's speculations, as well.

Since we're getting close to getting there, it's time for any of your uninformed speculations out there to be recorded for all posterity... biggrin.gif

I posted the following in that thread, but it really belongs here, so I'm reposting it here and inviting discussion. I figure that a lot of us don't bother to read the boards we don't stay actively involved with, so for all of you, this is new. Otherwise, I apologize for the repetitiion!


Look at the vertically-exaggerated image posted here.

Home Plate seems very obviously, in this stretched image, to be the remnant of an impact crater. There are several impact crater remnants in the inner basin, here. Each seems to have been formed in a surface that was a good many meters higher than the present surface -- those missing several meters have been deflated from this terrain, by some process, leaving the shocked "pedestal" remnants of the deeper cratering forms.

Remember, when you make an impact crater, you don't just affect the surface. The disruption caused by the cratering event goes well under the surface, consisting of impact melt (if the impact is energetic enough) and shocked, brecciated rocks.

The crater remnants we're seeing on the surface look like the brecciated and shocked rocks that were originally created in a bowl-shaped lining beneath this cluster of impact craters. I can see traces of at least five different craters within the inner basin, here. (The ridge of rock Spirit is passing right now is, in fact, a small crater remnant.)

As for Home Plate, it sits within the largest and most well-defined of these crater remnants. Maybe such layers were exhumed in *all* of the craters here, and have since been completely eroded away -- but that doesn't seem right. We have traces of several craters, and in only one of them do we see any trace of this lighter-colored material.

I'd have to think that either the impact target composition was different where the Home Plate impact occurred -- which seems a little unlikely when you consider some of these impacts are only a few tens of meters apart -- or that some other substance was deposited in Home Plate crater that wasn't deposited in the other craters. (Or that has been completely deflated from the other craters, if it ever existed there.)

So, logic *seems* to point towards post-cratering material deposition accounting for the light-rock ring. Personally, I think it could have been water deposition. Home Plate could have been a puddle that was filled and dried thousands of times (maybe with an internal artesian spring) that resulted in aqueous transport and deposition.

Or, it could have just been a good wind trap and it trapped a lot of light-colored dust. Hard to say.

I'm not only interested in the light-rock ring's composition, I'm getting very curious about the erosion process that deflated the original surface. Could aeolian erosion have deflated *that* much surface, even over a few billion years? Do we need to postulate aqueous erosion, or even glacial erosion?

Maybe the specific composition and erosion patterns we see on the light-rock ring will help us puzzle that out.

-the other Doug


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“The trouble ain't that there is too many fools, but that the lightning ain't distributed right.” -Mark Twain
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CosmicRocker
post Jan 27 2006, 05:54 PM
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This is off topic, but I couldn't help but notice that this topic has thrown the "Ads by Google" a real curve ball. laugh.gif


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Posts in this topic
- dvandorn   Home Plate Speculations   Jan 25 2006, 04:10 PM
- - general   Eroded core of a volcano   Jan 25 2006, 04:38 PM
|- - algorimancer   Odds are that it is evaporite, with volcanic ash b...   Jan 25 2006, 09:50 PM
- - Marz   QUOTE (dvandorn @ Jan 25 2006, 10:10 AM)So, l...   Jan 25 2006, 04:45 PM
- - Bill Harris   Good question, but we won't know for sure unti...   Jan 25 2006, 04:52 PM
- - Phil Stooke   Very interesting topic - and a good idea to move i...   Jan 25 2006, 04:53 PM
|- - john_s   QUOTE (Phil Stooke @ Jan 25 2006, 04:53 PM)HP...   Jan 25 2006, 06:03 PM
|- - The Messenger   Given the clean lines on the rim, I would go with ...   Jan 25 2006, 07:26 PM
- - space_student   Just to throw out an alternate hypothesis, perhaps...   Jan 25 2006, 07:33 PM
- - general   Could these strange 'sandwich'rocks be an ...   Jan 25 2006, 07:39 PM
- - Bill Harris   I wouldn't be suprised if, just as the Homepla...   Jan 25 2006, 07:40 PM
- - MaxSt   I think Home Plate is very salty.   Jan 25 2006, 09:09 PM
- - RNeuhaus   I put my toughts on the following. The Home Plate...   Jan 26 2006, 04:09 AM
- - CosmicRocker   I have to get in on this crapshoot. Although I ...   Jan 26 2006, 05:38 AM
|- - Shaka   QUOTE (CosmicRocker @ Jan 25 2006, 07:38 PM)O...   Jan 26 2006, 06:18 AM
- - general   Thank you, thank you. *bows*   Jan 26 2006, 07:40 AM
- - djellison   Didnt pitchers mound get mentioned by Steve like, ...   Jan 26 2006, 10:12 AM
- - vikingmars   For your info, excerpts from the 2002 original Gus...   Jan 26 2006, 10:31 AM
- - Bill Harris   QUOTE (djellison @ Jan 26 2006, 04:12 AM)Didn...   Jan 26 2006, 01:55 PM
|- - ustrax   I'm not certain but I have the impression that...   Jan 26 2006, 01:59 PM
||- - general   QUOTE (ustrax @ Jan 26 2006, 02:59 PM)I'm...   Jan 26 2006, 03:03 PM
|- - silylene   QUOTE (Bill Harris @ Jan 26 2006, 01:55 PM)At...   Jan 26 2006, 03:42 PM
|- - vikingmars   Here are the 2 major links featuring Home Plate (f...   Jan 26 2006, 05:04 PM
|- - Chmee   QUOTE Here are the 2 major links featuring Home P...   Jan 26 2006, 05:27 PM
|- - RNeuhaus   QUOTE (vikingmars @ Jan 26 2006, 12:04 PM) He...   Jan 26 2006, 06:33 PM
||- - Oersted   This was my idea back from January 14: "Poss...   Jan 26 2006, 06:35 PM
|- - Shaka   QUOTE (vikingmars @ Jan 26 2006, 07:04 AM) He...   Jan 26 2006, 06:54 PM
|- - vikingmars   ....because at that time, no much was named there,...   Jan 26 2006, 07:53 PM
- - gpurcell   I'm going to go out on a limb and argue for a ...   Jan 26 2006, 05:14 PM
- - CosmicRocker   I couldn't verify the origin of the term ...   Jan 27 2006, 04:07 AM
- - Bill Harris   I do recall that when Spirit first topped Husband ...   Jan 27 2006, 04:19 AM
|- - vikingmars   In fact, at the beginning of the mission, Pitcher...   Jan 27 2006, 10:21 AM
|- - Shaka   QUOTE (vikingmars @ Jan 27 2006, 12:21 AM)- i...   Jan 27 2006, 07:28 PM
|- - Bob Shaw   I bid for 'Baby Mound' as the Official Mar...   Jan 27 2006, 08:39 PM
|- - ElkGroveDan   QUOTE (Bob Shaw @ Jan 27 2006, 08:39 PM)I bid...   Jan 27 2006, 08:49 PM
|- - Bob Shaw   QUOTE (ElkGroveDan @ Jan 27 2006, 09:49 PM)If...   Jan 27 2006, 09:27 PM
|- - Shaka   HEY, Who let 'Jolly Jock' in the gate? O.K...   Jan 27 2006, 10:20 PM
||- - Bob Shaw   QUOTE (Shaka @ Jan 27 2006, 11:20 PM)HEY, Who...   Jan 27 2006, 10:38 PM
||- - Shaka   What. You mean that Limey game that takes 6 weeks ...   Jan 27 2006, 10:48 PM
|||- - Shaka   AND they wear sweaters while they play it!   Jan 27 2006, 10:51 PM
||- - imipak   QUOTE (Bob Shaw @ Jan 27 2006, 10:38 PM)Do wo...   Jan 31 2006, 08:31 PM
||- - Shaka   QUOTE (imipak @ Jan 31 2006, 10:31 AM)I'm...   Jan 31 2006, 09:40 PM
|||- - Bob Shaw   QUOTE (Shaka @ Jan 31 2006, 10:40 PM)Hey, Pal...   Jan 31 2006, 09:46 PM
|||- - Shaka   QUOTE (Bob Shaw @ Jan 31 2006, 11:46 AM)It...   Jan 31 2006, 10:50 PM
||- - djellison   QUOTE (imipak @ Jan 31 2006, 08:31 PM)I'm...   Jan 31 2006, 10:24 PM
||- - Shaka   QUOTE (djellison @ Jan 31 2006, 12:24 PM)/eng...   Jan 31 2006, 10:53 PM
||- - helvick   QUOTE (djellison @ Jan 31 2006, 11:24 PM)I...   Jan 31 2006, 11:42 PM
||- - Shaka   QUOTE (helvick @ Jan 31 2006, 01:42 PM)As (po...   Feb 1 2006, 12:27 AM
|- - dvandorn   QUOTE (Bob Shaw @ Jan 27 2006, 03:27 PM)What...   Jan 28 2006, 12:56 AM
- - Phil Stooke   I have been following names closely, and I've ...   Jan 27 2006, 04:23 AM
- - aldo12xu   And here's a coloured version cropped from Dan...   Jan 27 2006, 04:35 PM
- - CosmicRocker   This is off topic, but I couldn't help but not...   Jan 27 2006, 05:54 PM
|- - stevesliva   QUOTE (CosmicRocker @ Jan 27 2006, 12:54 PM)T...   Jan 27 2006, 10:56 PM
|- - djellison   QUOTE (stevesliva @ Jan 27 2006, 10:56 PM)I w...   Jan 28 2006, 01:16 AM
- - odave   I expect to see ads for DVD sets of "The Hone...   Jan 27 2006, 06:26 PM
- - Bill Harris   QUOTE ...bedding which will look very similar to t...   Jan 27 2006, 09:17 PM
- - tdemko   My shots in the dark: material: sulfate-cemented,...   Jan 27 2006, 10:49 PM
- - CosmicRocker   OT, again. Personally, I'm happy to see the a...   Jan 28 2006, 05:27 AM
- - paulanderson   Today's MER update makes interesting reference...   Jan 28 2006, 05:30 AM
- - nprev   Hmm...If HP is indeed a volcanic structure, I wond...   Jan 28 2006, 06:09 AM
- - CosmicRocker   Whoah! That was an interesting press release,...   Jan 28 2006, 06:25 AM
- - edstrick   I find Silylene's ideas presented several post...   Jan 28 2006, 10:25 AM
- - Bill Harris   Light-toned layered and widespread deposits on Mar...   Jan 28 2006, 10:57 AM
- - Myran   QUOTE CosmicRocker said: I wasn't expecting to...   Jan 30 2006, 11:51 AM
|- - Bob Shaw   QUOTE (Myran @ Jan 30 2006, 12:51 PM)Yes frot...   Jan 30 2006, 02:47 PM
- - Richard Trigaux   We have a model of Husband hills right on Earth, a...   Jan 30 2006, 03:58 PM
- - Bill Harris   That is a good analogy, Richard. I've learned...   Jan 31 2006, 01:25 AM
|- - Richard Trigaux   QUOTE (Bill Harris @ Jan 31 2006, 01:25 AM)Th...   Jan 31 2006, 02:19 PM
|- - RNeuhaus   QUOTE (Richard Trigaux @ Jan 31 2006, 09:19 A...   Jan 31 2006, 03:51 PM
||- - tty   QUOTE (RNeuhaus @ Jan 31 2006, 05:51 PM)I do ...   Jan 31 2006, 08:37 PM
||- - RNeuhaus   QUOTE (tty @ Jan 31 2006, 03:37 PM)It might w...   Feb 1 2006, 02:12 AM
|- - Richard Trigaux   QUOTE (Richard Trigaux @ Jan 31 2006, 02:19 P...   Jan 31 2006, 04:40 PM
|- - Bob Shaw   Here's a thought: apart from Devon Island, whi...   Jan 31 2006, 08:01 PM
|- - tty   QUOTE (Bob Shaw @ Jan 31 2006, 10:01 PM)Here...   Jan 31 2006, 08:28 PM
- - Bill Harris   Correct, "analogous mechanism or process...   Jan 31 2006, 03:27 PM
- - dvandorn   Speaking of cricket... I used to live in an integ...   Feb 1 2006, 02:01 AM
- - Richard Trigaux   What do you think, you all, that Homeplate is a fo...   Feb 1 2006, 08:48 AM
|- - Shaka   QUOTE (Richard Trigaux @ Jan 31 2006, 10:48 P...   Feb 1 2006, 07:38 PM
- - Bill Harris   This is wild... I was reviewing recent imagery, an...   Feb 1 2006, 09:28 PM
|- - Bob Shaw   QUOTE (Bill Harris @ Feb 1 2006, 10:28 PM)Thi...   Feb 2 2006, 10:34 AM
- - CosmicRocker   OMG! That whole thing went right over my head...   Feb 2 2006, 06:30 AM
- - alan   The of edge Homeplate is visible. Speculations a...   Feb 2 2006, 04:58 PM
|- - Richard Trigaux   QUOTE (alan @ Feb 2 2006, 04:58 PM)The of edg...   Feb 2 2006, 06:39 PM
- - aldo12xu   Well, it looks too rough textured to be, say, a la...   Feb 2 2006, 05:53 PM
|- - Marz   QUOTE (aldo12xu @ Feb 2 2006, 11:53 AM)Well, ...   Feb 3 2006, 12:03 AM
- - atomoid   yup, that picture uses the "R1" 739nm fi...   Feb 2 2006, 10:26 PM
|- - Bob Shaw   As ever, the closer we get to something the less w...   Feb 2 2006, 11:32 PM
|- - tty   QUOTE (atomoid @ Feb 3 2006, 12:26 AM)Here...   Feb 3 2006, 11:46 PM
- - Shaka   Dam' How can something look so prominent from...   Feb 3 2006, 03:32 AM
- - Bill Harris   There is a simple explanation for the lack of tona...   Feb 3 2006, 04:48 AM
- - dvandorn   Guys -- if you compare the pancam image in which a...   Feb 3 2006, 04:49 AM
- - edstrick   Shaka: "Dam' How can something look so pr...   Feb 3 2006, 10:41 AM
- - Bill Harris   And also, remember that we are used to seeing Home...   Feb 3 2006, 10:52 AM
|- - sattrackpro   QUOTE (Bill Harris @ Feb 3 2006, 03:52 AM)The...   Feb 3 2006, 12:59 PM
- - Bill Harris   Umm, I wasn't too clear. Although there is app...   Feb 3 2006, 01:18 PM
- - Richard Trigaux   It all looks strange, perhaps the strangest of all...   Feb 3 2006, 02:29 PM
|- - Richard Trigaux   QUOTE (Richard Trigaux @ Feb 3 2006, 02:29 PM...   Feb 3 2006, 07:49 PM
- - edstrick   I'll stick with my fossilized pizza-crust-of-t...   Feb 3 2006, 09:59 PM
|- - Bob Shaw   QUOTE (edstrick @ Feb 3 2006, 10:59 PM)I...   Feb 3 2006, 11:09 PM
- - Bill Harris   Bob, Ed-- shush. I've been playing with a c...   Feb 3 2006, 11:38 PM
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