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View Full Version : Defining Mountain Locations Through Tectonic Plate Movement



gspRooster
01-24-2014, 01:30 AM
I've seen a number of people asking for help or suggestions on defining tectonic plate movement because they feel that will help them better understand where they should be placing certain geographical features in the world, but I haven't yet seen (and my sincerest apologies if it's already here and I just haven't found it), an illustrated explanation designed to help people better understand this phenomenon. I will attempt to do that here.

When discussing or considering plate tectonics in terms of defining geographic landmasses, remember your world is a fictional world, so it doesn't have to make 100% sense. It may deliberately make no sense whatsoever, but that is up to you. If you are aiming for some degree of realism though, the following should be helpful.

Think of your world as an egg. Then go watch this video of eggs exploding in a microwave. COOL PHYSICS EXPERIMENT - Exploding Eggs in Microwave - Slow Motion - Full HD.mp4 - YouTube (http://www.youtube.com/watch?v=aaCcjQgMaOc)

Now that we've got that visual, think of your world like this. Inside your world is a hot, pressurized, liquid core, moving and churning and building up bubble of pressure in every location it can. Those bubbles of pressure can cause different kinds of releases.

1 - As you saw in the video, they can release slowly, and ooze through a weak point in your world's structural integrity. Over time generating landmass as magma pours into the ocean or out onto existing land and builds upon itself, turning that molten liquid core into a cool, outer shell. The magma will bubble at the slow point and churn beneath it. Consider this image when you visualize this.
http://i.imgur.com/YEs94Aw.gif (http://imgur.com/YEs94Aw)

2 - Alternatively, over time, excess pressure can build up at one of those weak points in such a way that it causes fractures along the path of least resistance, generating further kinetic motion as that energy is released over a wider area. This swift kinetic motion is what drives the movement of tectonic plates, generating earthquakes as the motion of one plate into another forces a collision. Consider this the secondary explosion of the first egg. Wherever your world's structural integrity is weakest, the internal magma is going to try to push through. When it does, it is essentially pushing the fractured pieces of a larger landmass in several different directions. In an object with sufficient mass, like a planet, this results in the pieces colliding with each other rather than hurtling off into space. Consider the following image and remember these basic guidelines.

Big landmasses compress little landmasses where velocities converge. - Example in the Phillipine plate being crushed by the Pacific, Eurasian and Australian plate.

Objects that appear to be moving away from multiple objects in an unnatural way may not be "moving" in the conventional directional sense the way you would expect a single piece to move, because you are thinking of that plate as an individual object when you shouldn't. Think of it is a piece of a larger object that has been split down a weak point in its structural integrity into two separate, smaller objects. Consider this image in the context of Africa and South America being a single plate, being forced apart at a weak point, similar to an exploding egg, and suddenly their outward movement away from each other despite the fact that they are moving into much larger plates makes sense. Higher pressure is a greater driver of movement than total mass. (This is a similar operating principal as a tiny bullet penetrating a 1/4 inch metal plate. The velocity, generated by the gaseous pressure buildup that fires the bullet, is more important than the weight of the object being moved.)
http://i.imgur.com/bmJtovrl.jpg (http://imgur.com/bmJtovr)

3 - Volcanic and tectonic forces are most prevalant along weakpoints and long fracture lines, as demonstrated by the massive amount of activity in the tectonic plate boundaries of our own world. However, they are not delegated to ONLY those locations. A weak point in the crust of a planet can appear anywhere where sufficient pressure exists to push through the crust. These weak points can, over time, grow into extended fractures of their own, breaking a larger plate into two smaller ones. The following image shows volcanic activity in the center of the Pacific plate. A weak pinhole in the center of an otherwise massive plate. Also, earthquake and volcanic activity in the center of the Africa, and earthquakes in the center of the North American plate suggest a shift of land along a microfracture in those plates that can very conceivable, given sufficient time and pressure, splinter those larger plates into separate smaller plates.
http://i.imgur.com/oSK1w1Ul.gif (http://imgur.com/oSK1w1U)


So the general idea of it is this...

Draw up your world, pick some arbitrary lines on your globe that you want to call your weak points - the fracture lines - and draw a couple, maybe three or four, very large plates. Then on each one of those plates, pick another weak point, and from there draw out another fracture line. The two pieces of that plate, if equal in size, should separate and go in opposite directions, giving a potential for underwater shelfs, land valleys, or volcanic activity. If one piece is substantially larger than the other, the small piece may get stuck between two larger pieces and become immobile, but be compressed on all sides by the larger pieces. Wherever you have plates moving in the same direction, you have definite mountain ranges, and high potential for volcanic activity. Think of the magma like a pimple, when you squeeze the sides, it pops. The same is true for two tectonic plates compressing a pocket of magma. It's going to push out through a weak point. And any point where you have two large objects moving towards each other is going to cause a crash, the result of that is a mountain. ;)

I hope this is helpful. :)

gspRooster
01-24-2014, 01:35 AM
Actually, I think I put this in the wrong location. Would someone be so kind as to move it to the appropriate location? Maybe tutorials?

Jalyha
01-24-2014, 02:12 AM
Omg thank you

gspRooster
01-24-2014, 02:52 AM
No problem. :) If I find the time I may try to refine this a little more and make it more "tutorial-y". Right now it sort of reads like a science project. haha