[X] My Assistant

[tty]

There could be different density gradients of things mixed with the organic layers that cause it to set up into differing layers. (Earth analog: the undercurrent that drives Earth's ocean circulations - these cause actual rivers under Earth's oceans. Nightclub analog: The layers in a tequila sunrise.)

There are even better terran analogs. The submarine canyons which cut through the continental shelf and slope are thought to be formed by turbidity currents (=mud). The are found mostly, but not exclusively, offshore outside the mouths of the largest rivers.

[Juramike]

There's another possibility: these submerged channels are carved during dry seasons (in summer and autumn) when the sea level is much lower and rains are not so heavy.

I even suspect that there's a very complicated system of cross-flow between the great lakes. Look at this twisted delta for example.

That's a beautiful example, Olvegg!

I can almost imagine a real subtle topographic break between the two long channels that you indicated with light blue left to right arrows. There might be just another (subtle) topographic break on a left right line parallel and slightly above the higher of the long channels. This might be the natural dam for the lake.

There's a teeny little dark channel that feeds into the upper long channel right at the tip of the blue arrow. I'll bet when the lake is down, that the fluids in the ridge section drain down this teeny channel into the upper long channel and flow to the left.

I think the light blue arrow on the far left might be reversed. This might be the main outflow for the lake (Notice how all the channels on the lake side near the light blue arrow are really, really stubby. They don't extend into the lake. I'm guessing the lake is draining out these channels to the bottom of the image. I'll also guess that when the lake drains, it backs up the green arrow channel so that it almost does a "river capture" of the upper light-blue arrow channel. I'll bet the topography is extremely subtle - like a tidal slough. Check out aerial images of the U.S. east coast intracoastal waterway (anywhere from coastal New Jersey south to N Florida) or aerial images of the Snohomish River in N.W. Washington State.

When the lake is low, I'll bet the upper light blue channel drains into the "left light blue channel" and drains away from the lake. I also suspect that the darker channels in the upper left of the image are draining the natural dam portion down to the bottom of the image also.

Nice catch!

-Mike

[nprev]

Could just be a result of the messing about enhancement process, but that gives me goosebumps...

Island, I dub thee (informally, of course; the discoverers possess the fundamental right to affix a permanent nomenclature) "New Manhattan"! Stu, mind-blowing as always...careful, you're rapidly earning the title of 'Imagesmith' in addition to Poet Laureate!

Only thing that bugs me is that linear sharp cutoff at about 5:00 on NM...looks like a processing artifact, but in Stu's previous image it also looked like there were some similarly aligned features directly to the left of the cutoff (with respect to his current image). Is this possibly a (very recent in appearance!) fault line?

[Juramike]

Nprev,

I think it's a processing artifact. But there do seem to be trends going up-down in Stu's image. The cute little ridge on the far peninsula (about 1 o'clock). And the streams seem to have an up/down trend (check out the river jog at 7 o'clock in the image).


Hmmm. I wonder.....

Which way is North in this image? Where is the island centered?

What is the ratio of inner diameter/outer diameter? (calling the island the inner diameter, and the outer basin the outer diameter)
If it was originally circular, what is it's squish vector and squish ratio?

Could the island be an uplifted and heavily eroded bright center dark halo object? Like the putative diapirs?

-Mike

[Stu]

Which way is North in this image? Where is the island centered?-Mike

This might help to place "New Manhattan" (like that!) in context...

[nprev]

Mike, funny you should ask...I really don't see any prima facie evidence of an impact or "volcanic" origin for NM. It looks to me very much like an outcrop of highly (and I mean highly) erosionally-resistant terrain that has survived the trevails of this environment in a relatively pristine state. Maybe it's mostly water ice, something like an exposed batholith on Earth?

[Juramike]

I'm thinkin' potential diapir. Like the Mitten feature on Europa. A diapir would rise in the center, but a thin ring around the diapir would subside.

So you'd get a central rise (not necessarily erosion resistant, but in this case it might be) with a moat of subsided material. (like the Mitten feature on Europa).

It might not be a huge difference in elevation. The Mitten diapir on Europa had an altitude difference of ca. 200 m above average elevation, with a "moat" of about 50-100 m below average elevation. Similar elevation differences were seen for diapirs in the Conamara Chaos region as well.

-Mike

[nprev]

Sounds reasonable...but look at how rugged the interior sections of this thing are, seems as if the upthrust was rather vigorous, perhaps atypical for a diapir (caveat: this ain't Earth or even a conventional terrestrial planet). Either it's really recent in origin, or it's tough as nails wrt indigeneous erosional forces. What's your read, Mike? I'm honestly puzzled by this island, and think that its very existence has much to tell us. (To say nothing of that little chain of smaller islands right off the lower right corner...I informally dub them "The Keys".)

[Juramike]

It definitely looks rugged and carved up by erosion in the interior.

But it doesn't take much elevation differential to provide a really impressive shoreline.
(A local case in point is Falls Lake just north of Raleigh, North Carolina - really cool-looking fractal shoreline, maximum elevation difference between lake surface and highest surrounding point is about 100 feet. (Check it out on Google Earth, it looks like it would fit in well on Titan). Falls Lake is a man-made lake that flooded river valleys which gave rise to the fractal pattern - similar to what I think is happening here.) [The flooded river valleys part - not the man-made part]

The other thing to consider is that perhaps fluid erosion is a relatively recent thing on Titan?
Maybe the diapir came up a long time ago, then the climate kicked in and has been working on it ever since?

Or maybe there was a recent upthrust that pushed a previously eroded and buried diapir and it's moat back up into the weather?

The surrounding areas look also pretty carved up, so I don't think this island was singled out for uplift. I'd guess that it is above the fluid level as much as the surrounding carved up areas are as well.

I hope they got altimeter data over this feature, that would really help give an idea of just how high and rugged the overall terrain is.

[I think this island is a polar equivalent of Bacab Facula except it is located in the polar shizzle deposition zone, it's been eroded by seasonal rains on a regular basis for a while, and it's moat filled in by a methane lake.

Another possibility is that it is similar to one of the bright islands from the Equatorial Sand Seas - is there a chain or ridge of rugged areas in a line? Maybe they are tectonic in origin.]

-Mike

[nprev]

Yeowzah. Well, all I got to say is that if this was one of my infant daughter's diapirs I probably wouldn't be here to tell the tale...(yeah, cheap one, sorry, couldn't resist!)

Still interested in the apparent compositional differences between NM and the surrounding terrain...although NM does look like a detached segment of the leftmost mainland in Stu's view.

On Earth, such separation of similar landforms is usually the result of plate tectonics, yet most of Titan (as yet examined) shows no compelling evidence of this process on a global scale. Do you suppose that this region is exhibiting localized tectonic activity, presumably facilitated by the long-term presence of a lubricating fluid? (Blue-skying here big time, but what the hell: alien world, alien thoughts...)

[belleraphon1]

Yeowzah. Well, all I got to say is that if this was one of my infant daughter's diapirs I probably wouldn't be here to tell the tale...(yeah, cheap one, sorry, couldn't resist!)

(Blue-skying here big time, but what the hell: alien world, alien thoughts...)

As a new grandfather, I have now gotten quite expert at observing and changing diapirs. However I do not think NM qualifies here.

We have to remember that these are radar images, which may penetrate some of the overlaying materials and make the deciphering even more interesting. It certainly looks like some of the shallower areas have not had much sediment settled into the lakebeds. The underlying terrain looks pristine.

Actually, some of the unflooded areas look like they have sediments or subdued expanses.... has the liquid washed this overburden off in the flooded areas?

What a beautifully complex terrain!

Will be interesting to see what changes come as the seasons advance.

Craig

[nprev]

Actually, some of the unflooded areas look like they have sediments or subdued expanses.... has the liquid washed this overburden off in the flooded areas?

What a beautifully complex terrain!

Will be interesting to see what changes come as the seasons advance.

Craig

Had similar thoughts myself, Craig...wondering if some of these seemingly submerged channels are seasonal features with a periodicity of, say 14.5 years.

Not to belabor a point...but Titan is alien, period. It might look like Earth in some particulars and spectra, but it isn't. We'll fully understand it someday, but not from Cassini, bless her to the nth power...we'll see some of Titan's wonders, but never quite enough.

This is not a criticism, but an expression of awe and surprise. Cassini is versatile enough to provide salient glimpses of Titan, and that's all that could possibly be asked of such an audicious mission to an unknown set of worlds...the designers did well, and in a more just reality they would sweep the Nobels. We have a lot to learn about Titan, but a far better idea of what questions to ask, and thereby what instruments and missions to design. Now, that will be a legacy!!!

[belleraphon1]

Had similar thoughts myself, Craig...wondering if some of these seemingly submerged channels are seasonal features with a periodicity of, say 14.5 years.

Not to belabor a point...but Titan is alien, period. It might look like Earth in some particulars and spectra, but it isn't. We'll fully understand it someday, but not from Cassini, bless her to the nth power...we'll see some of Titan's wonders, but never quite enough.

Agree.... CASSINI will write the text for the NEXT set of questions. This is how we explore. I am old enough to remember PIONEER11's Saturn flyby in 1979 (actually a LOT older than that). Back then the debate was over a thick versus thin atmosphere. Some reserchers felt that the methane gas detected on Titan was buffered by a another gas, nitrogen, to make a thick atmosphere, while others felt that methane was the chief ingredient and that the atmospher was thin. It was hoped that PIONEER11 would be able to take a measurement of the day/night temperature difference in the atmospshere..... a big diff would mean thin air.
Unfortunately, a thunderstorm over the Deep Tracking site caused the loss of this data. So we had to wait for Voyager 1 to make this determination.....

But now... I am amazed and happy to see what CASSINI can do to extend our knowledge of this magnificent world. Back in 1979 I could not have dreamed to be seeing what we now see. And to be able to
play with the data, and perhaps even make our own contributions to this effort.

WOW indeed.

Craig

[ngunn]

Calling all image mages.... ALERT ALERT ALERT.....

Can some one line up http://photojournal.jpl.nasa.gov/catalog/PIA09217 from T28
with http://photojournal.jpl.nasa.gov/catalog/PIA09182 from T25?

Can I add another request? I note that the overlap around 'Manhattan' is to be used to provide relief data for the area. I was wondering if anyone here could produce a stereo pair? It would be nice if we were the first to see the 'skyscrapers', though from rlorenz's very welcome monosyllable we may not have long to wait for an official version.

[ugordan]

Here's an anaglyph showing the region of interest. I'm not sure how pronounced the stereo effect is, the look angle appears to be similar in both T25 and T28 swaths and noise in the data further reduces the stereo feel. T25 was obviously lower resolution (left eye red here) and some detail visible in T28 is harder to make out there. North is to the left.

If anyone would like a cross-eyed stereo pair instead, speak now or forever hold your silence...