Yep, I am struggling with the same thing. In some cases the best solution is to change the shape of the plate a little. In other cases I think that local "divergence" is covered by the movement of the adjacent plates and not necessarily liked to new crust formation. In other cases, if you want a more one-direction sort of movement, it's a matter of moving the Euler pole away from the plate.
Originally Posted by ascanius
About your question about Euler poles and rotation. Yes, you could do it with a compass on a flat surface (if the map was an ortographic projection centered on the rotation axis). I say this not being the mathematical expert, which I'm not, but the guy who has been fiddling and reading around. From my experience, different projections give totally different areas of crust creation and crust subduction around a plate.
To add my 2 cents to the rotation representation discussion, this is my rough and clumsy experiment on PShop. Just tried it with two plates.
As you can see, I filled the plates with different colors and then rotated them just a bit, enough to see what goes on on each segment of the boundaries. I borrowed ascanius' system to indicate the Euler pole and basic rotational direction of each plate.
- If I have a boundary between two or more plates and on each side of said boundary there's a different direction, how do you represent that? In the maps of Earth's tectonics everything fits so nicely, the segments of the boundaries are always one of the three types, either convergent, divergent or transformation, I don't see any case where in one side of the boundary the tendency is convergent and on the other side divergent, for example. Is that so because Earth tectonics fit perfectly so all the sides of the boundaries are the same; it does happen but is simplified to be represented; or am I missing something big?
Guess what I'm asking is:
- How do you represent when each side of a boundary has different directions that do not make a simple convergent, divergent or transformation boundary?
- What would that mean in the real world, if for example one side of a boundary had a divergent movement and the other a lateral/transformation movement? Would it depend on the relative speed to each other and/or their general direction as a whole?
Sorry if this is a very obvious and silly question.
- Also, in plate nș1, on the left side where it meets with plate nș12, I wasn't sure if the movement there was convergent or lateral. The white color does "push" into plate nș12, but because of the rotation, it felt to me that the movement there would be lateral.
Last edited by groovey; 05-28-2014 at 07:23 AM.
Well, here's a little more on a crash course on tectonics for a historian:
- the main engine for plates movement is the pull towards the areas where oceanic plate is being subducted. This excellent map is a good illustration of that.
In plate 1, to respect his, it means a movement towards the junction with 2 instead of a anti-clockwise rotation. Try moving the euler pole for plate 1 close to where you have the number 7 written down, that would also create a divergent boundary right in the middle of the ocean, where it would make more sense and it would solve your problem with that boundary.
The same reasoning applied to plate 2 means it would break in half (and actually that would explain that sea) - the land mass is being pulled into the massive sink that is the boundary with plate 5 wheres the west side of the sea is being puled into plate 1.
Of course, these are just ideas I'm throwing about and they will probably mess some of the work you have already so feel free to ignore them.
As for the boundaries that don't match in terms of absolute movement, what matters is their relative speed to each other. You can think of transform as "neutral" relative speed, so
divergent + transform = divergent,
convergent + transform = convergent
divergent + convergent = ... hmmm, avoid that or do as you please, depends on relative speed.
Last edited by Pixie; 05-28-2014 at 03:17 PM.
Thanks Pixie, that was really clarifying, and it'll help me a lot to know what the heck am I doing.
Pixie, I've been checking out your suggestions in the map. I see now what a huge difference it makes placing the Euler pole in one position or another, which I guess it's good because it gives more flexibility and control over the rotation.
I don't know if you literally meant that plate nș2 would break in half, but that's what I had in mind before the last version I posted, where nș2 also included half on plate nș3. To be honest I like this version I post now better. Would it work the way it is now and stay true to what you said? Plate nș2 pulled into nș1 (because of general direction and rotation/subduction) and the south-east of nș3 into nș5 because of rotation/subduction.
I need plate nș1 and 3 to pull into each other in the north to create a high mountain range "dividing" the two plates, and plate nș2 pushing on the north-west a bit into nș1 to create some mountains would also be great, thus my present proposal.
I also need volcanic islands on the south of plates 1 and 3 for colonization wars, thus why I'm so insistent of putting that island chain there btw plate nș6 and 7, but you and Ned both commented I placed most of the islands in rifts. I'm not sure if you meant those islands or the random ones I had all over the map, which I've removed for now in a hidden layer till I know where they fit (except those near the coast because I see those as an extension of the land mass). Wouldn't the subduction btw nș7 and 6, and nș6 with nș5 allow the creation of those islands there?
I don' think I managed too well to respect the principle of "the main engine for plates movement is the pull towards the areas where oceanic plate is being subducted", since I needed specific scenarios to happen to get specific mountain range areas.
I also don't think I managed to avoid convergent + divergent boundaries segments, so when it's time to add the symbols I'll have to cheat a little and decide on one or another.
The islands of the pole: could I get away with saying they are isolated continental fragments that separated from the continents a long time ago and got merged with the South pole plate, or is it too much? The little islands near said pole I could place around the little subduction area btw nș7 and nș15, or nș10 and nș15, but the bigger ones? Should I just move them to the NPole where subduction actually occurs?
All that said, do you spot anything that makes you want to rip your eyes off? Or that would improve what I have, before I start laying out the symbols on the boundaries?
P.S: Sorry for the long post, I know most of you reading are busy with your own projects.
Congrats, groovey! To my eyes, you nailed it. This is so close to finished I am truly jealous now. You have nice land shapes and fully explained by tectonics. And this map you have, with original boundaries in black and slightly colored plates after-movement, is perfect to see your reasoning.
Three minor things you can change very quickly:
- try rotating plate 4 on the opposite direction - it would be pulled into the subduction area with 5, it would diverge from 14 (14 is already diverging there) and it would explain the small gulf on its southern junction with the mainland.
- boundary between plate 2 and 3 should be much closer to the west side. That's ocean floor being created - to the west it's the actual plate 2 and is being subducted under plate 1 (meaning, it's disappearing) and to the east side it's just adding to plate 3 (meaning, it's not disappearing). After a few million years most of the existing sea floor would be part of plate 3.
- yes, the islands along the northern boundary of plate 6 are very plausible. But it is apparent that this plate is younger sea floor, bursting through the older parts of plates 1 and 5, which means it's plate 6 which stays on top, which means islands are formed on plate 6. The best place on Earth to show something similar is Tonga/Fiji... check this picture. The curvature of those boundaries needs to be opposite though (I can draw this if the wording isn't clear)
The map looks good. I don't see any other problems that Pixie hasn't pointed out. Keep up the good work
Wow, I'm honestly shocked! I know I lowered the bar of realism for my map and all, but still, I didn't really think I'd do so well on my first full try (though I did a lot of editing before having this version done).
Thanks guys, specially you, Godfather Pixie, and you have no reason to be jealous, your little penguin alone with the heightmap kicks more ass than my whole map.
I'm feeling a bit crappy today (had a wedding party last night, not for me, and though I didn't drink my head is resenting), so I'll be sure to fix your suggestions on the map tomorrow when I'm better suited to think.
Feeling very excited though, I've been waiting about 4 years for this moment and at least it seems I'm on the right path to get a finished, decent map, thought there's still a lot to do, first of all, get the tectonic boundaries done. I don't think I have it in me to make it look as great as Akubra did, but I might try something similar and if it doesn't work I'll just keep it ugly but simple. And I forgot for a moment that I still need to place some islands in subduction areas, but that job doesn't scare me so much.
Last edited by groovey; 06-01-2014 at 03:37 AM.
Hey groovey, I'm joining the others in saying that your map looks wonderful and very realistic. It seems there's another word for it, but I forgot - oh wait, I've got it: it looks groovy!
Cheers - Akubra
Looking forward to see that "polished" map. I've been trying to create the same sort of map and although time consuming, it isn't as difficult as it seems at first sight. Just keep in mind your rotation movements when you do it.
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