All good questions... As you say, viscous fingering isn't a complete theory, nor is electrical arcing.

However, Electrical arcing tends to create extremely similar figures, with long thin branching arms CONSISTENTLY in the lab, whereas viscous fingering appears to take on a variety of morphologies.

Electrical arcing, in this regard seems to be more self-consistent than fingering.

As to why the phenomenon would be associated with the poles, I think I've already explained this, but if you look up Birkeland currents, IE the current flow between the sun and planets along filamentary pathways, you'll see that they are field-aligned. IE, they connect to the planet most strongly at or around the poles. This was demonstrated by Birkeland using his Terella device, and it is generally accepted that this is the causation of phenomena like the polar auroras of Earth, it's slowly being accepted that they cause the polar auroras of other planets (not quite there yet, but all thing being equal we must consider the possibility that the same structure is caused by the same process on all similar bodies).

As to blackening streaks associated with spiders... I thought you (Greg) were associated with martianspiders.com, the evidence is all over the place in the pictures there... Let me find a few examples, though I think I already posted several in my other responses in other parts of the hierarchy of this thread. But I'll repost, in case you missed 'em. They're on my blog too www.myspace.com/mgmirkin/ . The black streaks seem to rather well like the spiders. Though not every streak is directly over a spider, nor does every spider have a streak associated. But where therre are black streaks in the region there generally seem to be spiders, and they're usually overlapping more than "random chance."

Prime example:
http://www.martianspiders.com/e0702165b.jpg.htm

Note the bottom three spiders which all seem to have black streaking preferentially associated with them. I'd say this COULD be due to dust devils streaking the surface, and then a catastrophic dielectric breakdown in the same conductive area. Now, there may be cases where there is dust devil streaking and no catastrophic breakdown, or there may be catastrophic breakdown without a dust devil forming. But it seems like black streaks and spiders prefer forming together when they're in the same basic area. IE a lot of times you'll see black streaks going directly over the spider and little or NOWHERE else in frame. IE they're preferentially over the spiders... Interesting, no?

(Note the black spots almost ALL appear to be over the center or fringes of spiders?)
http://www.martianspiders.com/e0801508.jpg.htm

(A few of these are a bit faint, butyou can see the major spiders have black streaking associated.)
http://www.martianspiders.com/e0700829.jpg.htm

(Again)
http://www.martianspiders.com/e0800043.jpg.htm

(Weaker, butyou can see a few black spots associated over spiders.)
http://www.martianspiders.com/e1003496c.jpg.htm

Anyway, my thought is that in the electrical model:

1) Black streaking is part of a non-catastrophic discharge phenomenon associated with "dust devils."
2) Spiders or "Lichtenberg" figures are associated with catastrophic dielectric breakdown of the charged surface or subsurface strata.

The two are not mutually exclusive, nor does one necessarily lead to the other. But they both seem to preferentially form in the almost same spot on many occasions. And they seem to preferentially prefer the same spot in frame. IE you have 3 spiders in frame, and you have 3 areas of black streaking directly OVER the spiders or their extremities, rather than in between, or over non-spidered areas.

But like I said, you can have catastrophic (lightning) discharge without a slow discharge (dust devil) beforehand. And vice versa. You can have a slow discharge (dust devil) without an electron avalance sufficiently ionizing a path for catastrophic discharge. Or you can have a slow discharge in a region where either the atmosphere or the ground isn't sufficiently charged to create a dielectric breakdown in/on the surface.

BUT, and this is the big one. I think there CAN be instances where you get dust devils (slow discharge) which at some point reach a critical mass of ionization for an electron avalanche or dielectric breakdown leading to a catastrophic discharge sufficient to create Lichtenberg figures.

From what we've seen of Mars' "theoretical" magnetosphere, it's spotty at best. And it's perhaps NOT uniform. As such sonce side might be more prone to letting charged particles through where the Birkeland currents connect. Actually, based on recent re-perusal of Nasa's image archives. I think this might be true of a couple other planets as well. I say this because the observed emissions from the planets in the IR, UV or X-ray spectrum appears to be brighter on one pole than on the other... So, in this regard, depending on how the magnetosphere is being pinched by the solar wind, I think it might be feasible for ONLY ONE pole to be preferentially charged due to a weaker or thinner magnetosphere on that side. IE, there's less magnetosphere and possibly less atmosphere on that side, hence more charged particles could get through to saturate the surface on one pole than on the other.

Anyway, let me find the Nasa photos again... 1 sec. As we can see, the auroras happen in a ring around the pole:

Venus:

(Double-eyed vortex at both poles.)
http://thunderbolts.info/tpod/2006/arch06/060717doubleeye.htm

Earth:

(Auroras at the poles.)
http://earthobservatory.nasa.gov/Newsroom/NewImages/images.php3?img_id=17165
http://antwrp.gsfc.nasa.gov/apod/ap011114.html

Jupiter:

(Auroras)
http://photojournal.jpl.nasa.gov/catalog/PIA01254
http://photojournal.jpl.nasa.gov/catalog/PIA01257
http://photojournal.jpl.nasa.gov/catalog/PIA03155
http://antwrp.gsfc.nasa.gov/apod/ap980123.html
http://antwrp.gsfc.nasa.gov/apod/ap020301.html
http://antwrp.gsfc.nasa.gov/apod/ap030313.html

IO:
http://photojournal.jpl.nasa.gov/catalog/PIA03450

Enceladus:
http://photojournal.jpl.nasa.gov/catalog/PIA06432

Saturn:
http://photojournal.jpl.nasa.gov/catalog/PIA06436
http://photojournal.jpl.nasa.gov/catalog/PIA01269
http://antwrp.gsfc.nasa.gov/apod/ap050222.html
http://antwrp.gsfc.nasa.gov/apod/ap011223.html
http://photojournal.jpl.nasa.gov/catalog/PIA07008

Uranus:

(Aurora; bright side on one pole, "bright clouds" on the other. Not quite homogenous.)
http://photojournal.jpl.nasa.gov/catalog/PIA02963

http://hubblesite.org/newscenter/newsdesk/archive/releases/1998/35/
http://hubblesite.org/newscenter/newsdesk/archive/releases/2005/33/
http://hubblesite.org/newscenter/newsdesk/archive/releases/2004/05/
http://hubblesite.org/newscenter/newsdesk/archive/releases/1999/11/
http://hubblesite.org/newscenter/newsdesk/archive/releases/1997/36/

Neptune:
http://hubblesite.org/newscenter/newsdesk/archive/releases/2003/17/
http://hubblesite.org/newscenter/newsdesk/archive/releases/1998/34/
http://hubblesite.org/newscenter/newsdesk/archive/releases/1995/09/
http://hubblesite.org/newscenter/newsdesk/archive/releases/1996/33/
http://hubblesite.org/newscenter/newsdesk/archive/releases/1995/21/

Definitely appears that Uranus is more lively on one side than on the other, in terms of brightness... Neptune might also be. Though it's hard to tell... Anyway, it's possible that under some circumstance MArs or other planets could have one side preferentially exposed more than the other due to how its magnetosphere is composed. IE, if you have less magnetic protection on one side, it'll tend to get more charged particles heading that way. Or, if the specific charge (say negatively charged electrons) are/where more preferentially attracted to that particular pole of the magnet[osphere], then perhaps that side would be more preferentially charged. All I'm saying is consider the possibility. If we consider the planet as a gian magnet with a north and south pole. Perhaps a large mass of particles of a particular charge would be drawn more strongly to one pole than the other. Who knows. But we definitely see banding in the auroras of other planets. The same causative process (Birkeland currents) is likely the cause. I see no reason why physics would work any differently on Mars except the factit has a weaker magnetosphere protecting it, and a far more rarified atmosphere (so more charged particles would get trhough to the surface than arestopped by the magnetosphere or atmosphere). When ya' think about it, it kinda' makes sense. Yeah?

Likely the reason we don't get these discharges AS OFTEN is that we have a much moreactive magnetosphere protecting us from the charged particles in space. Also we have a very active atmosphere and ozone layer protecting us too. So since less charge makes it to the surface we will tend to see less charg[ING] and less [DIS]charging. But we DO see it. We just take it for granted when we do say "Ohh well, LIGHTNING... What can you do? It's just an act of God!" and re-seed lawns of golf courses and such...

Did I happen to mention what it does to the human body? Ohh, right, flesh lichtenbergs...

Or did I mention the scars it cuts in people's yards? Yes, that's right it CAN machine soil right up out of the ground. Hence the term Electrical Discharge Machining used in labs. It's used to eject matter out of the surface of an object. If it can be done with electricity in the lab, why not on a large scale on the face of a planet?

(note about half way down the page the large lightnig scar made on a field, and the lightning lightenberg made around a golf hole's pole when a bolt struck it.)
http://www.holoscience.com/views/view_mars.htm

So, as we can see, lightning is a very powerful force. And we know that electricity in a catastrophic discharge creates Lichtenberg formations which invariably create the same basic branching filamentary structure... Lightning can machine soil out of the surface. It creates fulgurites below ground (glassy filamentary root-like structures very similar to the Lichtenbergs captured in Acrylic). All we have to do is look...

http://en.wikipedia.org/wiki/Fulgurite
http://home.att.net/~amcnet/eventmain.html
http://www.menzelphoto.com/gallery/big/lightning6.htm

http://lichdesc.teslamania.com/

(Don't mind they're selling stuff, I just wanted Lichtenberg examples. They seem a great source.)
http://205.243.100.155/frames/interesting.html
http://205.243.100.155/frames/interesting3.html

Note how the Lichtenbergs are always consistently radiating from the point of discharge, and generally in a circular-ish pattern. Though other slightly different patterns can be formed depending on how the acrylic is charged. But they still branch from the point of discharge in an Electron avalanche that quickly dissipates charge and scars the material that's being discharged.

And the analogy between Earth and MArs you made is off-base. Mars is CONSIDERABLY different from Earth. It has little to no atmosphere, and mittle to no magnetosphere, thus little to no protection from charged particles emitted from the sun. We have the magnetosphere and the ozone layer plus the rest of the atmosphere. It takes considerably longer for the ground to acquire charge through all that layering and protection. Whereas Mars' rarified atmosphere and weaker magnetosphere make it ripe for acquiring charge from the field-aligned currents. Don't get me wrong, we acquire charge from the sun like any other body. It just has to go through a few more layers, and displays a much wider range of charge dissipation patterns. we get ground to cloud lightning, could to ground lightning, cloud to cloud lightning, ball lightning, polar auroras. But, when we do get massive lightning strikes, we do also get fulgurite formation and lichtenberg patterns burned into grass or soil. We also get excavation of rilles or "channels.' Perhaps not on the same scale as Mars, but we're also more insulated than Mars, too. So, that's the be expected. Less charge means less violent interactions, and smaller or less impressive Lichtenbergs and rilles. But we DO still get them. I'd guess that the larger the lightning strike the more impressive the formations will be. But, perhaps that's just me and the golf courses talking? And that poor bloke that got whipped by lightning.

I agree that discovery is a process of theorizing and then testing theory versus facts. I also appreciate your counterpoints. They're quite valuable. I like being shown things I haven't yet considered. It makes me think harder and flesh out the model. This is of course just a debate, I suppose. But if nothing else it's a test of the theory and any weak spots... To "work on." Still, I think the electrical model is more convincing than some other theories where gravity must be defied, or fluid dynamics work differently than in the rest of the universe. IF electricity works "as advertised," why not? Occam's razor after all. If the entirety of behavior can be modeled with one force or two forces instead of 3-5 forces... Which model is better? Dunno. But Occam might.

At least part of the reason I'm discussing here is to ferret out said "weak spots" or "dissenting opinions" so they can be adequately addressed in further iterations. Of course if I get plagiarized. I just point back to my voluminous dated e-mails and posts on the topic. ;o] Not that I'd expect anyone would want to stake their reputation on such a "non-mainstream" theory, even if it *IS* right. But, mainstream science marginalizes electricity, charge transfer, etc. in space. Until they recognize, many things will appear "mysterious." *wink*

Anyway, further comments/opinions appreciated. Hopefully I hit all the main points you were interested in?