zompist bboard

How has the planet changed over time, like Pangaea 140-65 Ma ago? Has anything like that happened? What has happened to Almea over the passage of time, continental drift and such?

XinuX wrote:How has the planet changed over time, like Pangaea 140-65 Ma ago? Has anything like that happened? What has happened to Almea over the passage of time, continental drift and such?

Sure. It's hard to see on a flat map, but the continents fit together, like Earth's.

One thing that never seems to get enough press is that Pangaea wasn't the original configuration-- just one stage in the dance. The continents have been bopping around for four billion years; Pangaea was about 200 million years ago.

I suppose no-one on Almea has proposed the theory of continental drift yet, though? Or have they? Maybe the Ilii?

butsuri wrote:I suppose no-one on Almea has proposed the theory of continental drift yet, though? Or have they? Maybe the Ilii?

The humans haven't; no one has good maps of the northern hemisphere, and I doubt the idea will occur till they do.

I'm not sure how advanced the ilii are scientifically...

I wonder if there were any Almean dinosaurs.

Um... hello? I do know that Pangaea was just one step in the dance - I was simply using it as an example. There's the Pan-African orogeny, the Permian Mass Extinction, Rodinia 1Ba ago... the list goes on.

Yes, but not everyone knows that, alas...at least in the past, too many textbooks presented Pangaea as if it were Step One. (I thought so myself as a child, before I grew older and deepened the scope of my reading.)

p@,
Glenn

Fair enough... I apologise if I offended anyone.

No problem--I just wanted to make sure you weren't offended.

p@,
Glenn

Although a history of the arrangement of the continents would be a good step... and even if the ilii/uesti don't have decent northern hemisphere maps, YOU, the supreme Bubba, the Ruler, he who supercedes even the ilii in power, wealth &c., Life and Death, Father Time and Mother Nature &c. have the best map possible... can you not work from that?

XinuX wrote:Although a history of the arrangement of the continents would be a good step... and even if the ilii/uesti don't have decent northern hemisphere maps, YOU, the supreme Bubba, the Ruler, he who supercedes even the ilii in power, wealth &c., Life and Death, Father Time and Mother Nature &c. have the best map possible... can you not work from that?

I don't really have good tools for it... someone should invent a computer with a spherical screen!

Good point...
What about VRML?

XinuX wrote:There's the Pan-African orogeny, the Permian Mass Extinction, Rodinia 1Ba ago... the list goes on.

Ooh, ooh! And don't forget bodies of water! There's the Panthalassic to balance Pangaea, the Iapetus Ocean, the Rheic, the Cannonball Seaway. . . . And my personal favorite, the Tethys. Now there was a Sea! I miss it.
Though Niobrara was good too, while it lasted. (The sea, not the river. At least, I think the other Niobrara is a river.)

zompist wrote:I don't really have good tools for it... someone should invent a computer with a spherical screen!

I take it you haven't had a globe of Almea made, then?

XinuX wrote:Although a history of the arrangement of the continents would be a good step... and even if the ilii/uesti don't have decent northern hemisphere maps, YOU, the supreme Bubba, the Ruler, he who supercedes even the ilii in power, wealth &c., Life and Death, Father Time and Mother Nature &c. have the best map possible... can you not work from that?

If I got it right, Mark usually takes the position of a scientist from Earth who for some reasons has access to Almean sources when he writes about that planet. So if noone on Almea knows it, he doesn't know it, either.

(Though that makes me wonder how he got the information for the pre-historical parts of the Historical Atlas)

Raphael wrote:If I got it right, Mark usually takes the position of a scientist from Earth who for some reasons has access to Almean sources when he writes about that planet. So if noone on Almea knows it, he doesn't know it, either.

Right, unless of course I can deduce things that the Almeans can't. (As an example, I can link the Chia-Sha languages to Eastern, but the Verdurians haven't done so.)

For consistency of viewpoint, I write like I have a mobile camera on Almea-- like I can see (or read) anything, but I can't dig up things or move the camera into the past.

Raphael wrote:(Though that makes me wonder how he got the information for the pre-historical parts of the Historical Atlas)

I probably depart from the model a bit there. I suppose I could say that it's just good historical deduction plus some anticipation of greater knowledge from elcarin or iliu sources.

And, GreenBowTie: I did have a globe of Almea while working out the global map, but I erased it. I'll do it again better someday...

Globe?
How did you make it?

Anonymous wrote:Globe?
How did you make it?

I've used two resolutely low-tech methods:

1. Take a ball, draw latitude and longitude lines on it, look at your world map, and redraw the continents on the ball. (Better yet, do this backwards, which is more likely to produce reasonable continents. A continent that looks OK on a flat map may turn out to be weirdly distorted on the globe.)

2. Draw a sinusoidal map of the world-- that's the same type as my main world map, except that each spear should be no more than 30 degrees wide. If you've done it right, you can cut out each spear (leave it connected to the next spear at the equator) and assemble it into a sphere. (Or paste them onto a ball, if you made the map the right size.)

There's a thread somewhere on the board where some clever whippersnapper took a Mercator flat map and mapped it using a graphics program onto a sphere. This is probably better than having a physical globe, since you can more easily export views of it; but it does mean you have to draw the planet in distorted form.

Glenn Kempf wrote:Yes, but not everyone knows that, alas...at least in the past, too many textbooks presented Pangaea as if it were Step One. (I thought so myself as a child, before I grew older and deepened the scope of my reading.)

Um, I thought so myself as a child, and still did until I read this thread. It never occurred to me there might have been a different configuration before that; it seemed such a good starting position, I suppose.

So it's been interesting reading here.

zompist wrote:There's a thread somewhere on the board where some clever whippersnapper took a Mercator flat map and mapped it using a graphics program onto a sphere. This is probably better than having a physical globe, since you can more easily export views of it; but it does mean you have to draw the planet in distorted form.

That was me, using xplanet (and one of Ranskaldan's maps). It's even worse than that, actually - the input image has to be Plate Car?e (AKA equirectangular, equidistant cylindrical) projection. Mercator's at least useful for navigation - the only place you see Plate Car?e is at NASA Mission Control (because it's easier to plot an orbital path).

It shouldn't be too difficult to make a filter to distort a map from Mercator to equirectangular (or vice versa) but I don't know of any, and I'm not a good enough programmer to write one myself.

Aidan wrote: Ooh, ooh! And don't forget bodies of water! There's the Panthalassic to balance Pangaea, the Iapetus Ocean, the Rheic, the Cannonball Seaway. . . . And my personal favorite, the Tethys. Now there was a Sea! I miss it.
Though Niobrara was good too, while it lasted. (The sea, not the river. At least, I think the other Niobrara is a river.)

Man, I really envy some people.

Hey, i sometimes wish that I was the urban planner who got to name all the new streets around the place . . . meanwhile some people are scrambling to find names for landmasses, bodies of water, lunar seas, extraterrestrial formations, which no human has ever seen with their own eyes, and yet we know they must (have) exist(ed)!

Yeah, I remember when i was younger playing with an animation in . . . grolier's i think it was, of continental drift. You could make the continents come together, blast apart, come together, blast apart . . . but although the video showed landmasses moving to form Pangaea, the voiceover only started once Pangaea was formed. I suppose we'd have little idea of what the actual shorelines were around then.

Hey, anyone named any of the landmasses that existed before Pangaea?

So Haleza Grise wrote: Man, I really envy some people.

Hey, i sometimes wish that I was the urban planner who got to name all the new streets around the place . . . meanwhile some people are scrambling to find names for landmasses, bodies of water, lunar seas, extraterrestrial formations, which no human has ever seen with their own eyes, and yet we know they must (have) exist(ed)!

Yeah. Richard Fortey has gotten to name at least one ocean, in addition to any number of trilobites. I want to name oceans. I recommend his books by the way: Life: A Natural History of the First Four Billion Years of Life on Earth and Trilobites!. (I get the feeling his titles are a study in contrasts )

So Haleza Grise wrote:Hey, anyone named any of the landmasses that existed before Pangaea?

One was mentioned earlier, actually; though not labeled as such. Rodinia was the last supercontinent before Pangea, it was around about 1.1 to .75 billion years ago. Before that we don't really have good enough informaton (yet!) to name anything specific. There just aren't enough rocks older than that around anymore.

It's not the rocks.
The reason we are able to date these things is due to molluscs. Yep, snails. However, there are no molluscs before 65 billion years ago, so we can speculate about the continent(s) on which they existed before that, but we can't say for sure. Thus the furthest back we can go, unless somebody discovers some billion-year-old snail shells, is Rodinia 1 Ba ago. (The climate in Britain, incidentally, would have been about the same a billion years ago as it is today. It had an ocean current up the same coast, and were in the same section of the hemisphere (though it was in the southern hemisphere).
I love geology.

XinuX wrote:It's not the rocks.

Whoops , you're right: the good fossils are the more critical part. I wasn't thinking.

Thanks for correcting me. Now I'm going to return the favor .

XinuX wrote:The reason we are able to date these things is due to molluscs. Yep, snails.

Well, not just molluscs. Trilobites are also extremely important. And other things.

XinuX wrote:However, there are no molluscs before 65 billion years ago, so we can speculate about the continent(s) on which they existed before that, but we can't say for sure.

I think you mean 650 million years ago. 65 billion years is 4 or 5 times the age of the universe . In keeping with pointing out that it's not just molluscs, I'll point out, not just were there no molluscs before about 650 million years ago, there were few or no animals that had any hard parts to them at all, thus very few fossils.

Before Rodinia, there aren't any animals at all, or other macroscopic organisms. And maybe not even any eukaryotes at all, just bacteria. An its hard to get too much info from bacteria fossils.

XinuX wrote:Thus the furthest back we can go, unless somebody discovers some billion-year-old snail shells, is Rodinia 1 Ba ago.

As implied above, nobody's gonna find any billion year old snails unless we've really missed something in geology/paleontology. However that doesn't mean we can never trace anything further back, because there are the rocks. And we can get info from just rocks. Not only can you match rock patterns back together, you can also get a good idea of what kind of condition a rock layer was layed down under. And some idea of its original position realtive to a pole by looking at the orientation of magnetic substances in the rock. And who knows what else we'll think of.

But for now, Rodinia is where we can trace back to.

pne wrote:

Glenn Kempf wrote:Yes, but not everyone knows that, alas...at least in the past, too many textbooks presented Pangaea as if it were Step One. (I thought so myself as a child, before I grew older and deepened the scope of my reading.)

Um, I thought so myself as a child, and still did until I read this thread. It never occurred to me there might have been a different configuration before that; it seemed such a good starting position, I suppose.

So it's been interesting reading here.

Don't worry--when I said "as a child," I meant "until college" (when I took a year and a half of geology).

p@,
Glenn