Mountain placement on first map (WIP)

[samkatz]

Hi everyone. I'm looking for a little feedback on a work in progress.

Below is my first attempt at worldbuilding, with mountain ranges and highlands marked in red (and light blue for the underwater one). Before I attempt to draw detailed mountains and figure out the river systems and climates, I wanted to make sure these all make sense. I've labeled them with letters to make talking about them easier.

Map.jpg

Does anything here look horribly out of place? Anywhere where you'd expect mountains where I have none? I imagine something isn't quite right, as I've been eyeballing (i.e. not figuring out) the plate tectonics. How do you all like the map in general?

[Deadshade]

On your place I would start by looking at the tutorials - there are many of them here and you'll find there answers on many of your questions.
I would say that you have too many mountains and that your coastline is too regular.
Also the circular mountain at the north pole (if you use a cylindrical projection) is not natural.

[Chick]

Hi Samkatz, welcome to the Guild!

If I can just suggest without a lot of detailed reasons, I'd say remove A, P, F, G, I, R, J, U and Q. They just don't make a lot of sense where they are.

Keep BCD but fill in from B to C.

V, S, T, and O are ok if you want them there as (for example) remnants of very old mountains mostly eroded away.

The ones that make sense tectonically are BCD, E, H, MKL.

N is probably best eliminated, but you can make a case for it, if you want it there for a reason.

[samkatz]

Thanks for the feedback, and for the welcome. I actually played around with N a lot so it would look right on a globe, as if it were moving toward the continent in the middle, away from the ocean that's split up by the projection, creating a mountain there. Here's a screenshot looking straight down on the north pole. I don't have anything to put it on a sphere except globizer.net. Is there any better (free) option out there?
Screen shot 2015-01-06 at 6.43.18 PM.png

I was thinking of A and P as (separate) older tectonic events. Is there some reason why that doesn't make sense? And what about J as the collision of the two pieces of land on either side of it?

[Chick]

I was thinking of A and P as (separate) older tectonic events. Is there some reason why that doesn't make sense? And what about J as the collision of the two pieces of land on either side of it?

You can certainly make that argument for any long mountain range you want, and that's fine. Just keep in mind that continent/continent collisions are actually pretty rare. Right now on Earth, the Himalayas are the only major ongoing one, and the other sizeable one is the Urals which is occurred in the early Triassic about 250-300 million years ago. There are smaller remnants around, but I suggest you don't make too many.

[Wingshaw]

Just keep in mind that continent/continent collisions are actually pretty rare.

This seems like a perfect time to ask why this is the case? A few years ago, I did some intensive study of plate tectonics and orogenesis, and I noticed that, as you say, there are few convergent boundaries on land, but I could never figure out why. Surely, when converging plates cause the closing of an ocean, it also results in terrestrial collisions.

Can anyone shed some light on this for me?

THW

[samkatz]

Here is version 2.0. I think it's a move in the right direction. Anything still a little dubious?
Map (2).jpg

[Chick]

It's primarily because most collisions of plates containing continental crust aren't as direct as India is. When there is an angle, the huge resistance turns them into slip/slide boundary where the plates slide along each other. The San Andreas fault is an example of this.

In order to have a direct collision of continents such as is building the Himalayas, there must be no ability of the continental plates to go anywhere else.

[Chick]

Here is version 2.0. I think it's a move in the right direction. Anything still a little dubious?

That looks much better, Sam! Very reasonable and realistic looking to my geologist eyes.

[Deadshade]

This seems like a perfect time to ask why this is the case? A few years ago, I did some intensive study of plate tectonics and orogenesis, and I noticed that, as you say, there are few convergent boundaries on land, but I could never figure out why. Surely, when converging plates cause the closing of an ocean, it also results in terrestrial collisions.

Can anyone shed some light on this for me?

THW

I think that the explanation is simply probabilistic.
The engine of plate tectonics is the convection in the mantle.
The closest analogy to the mantle convection dynamics is that : https://www.youtube.com/watch?v=jUv4Cid3OnE
Now these chaotic up and down movements are constrained by the spherical boundary so that they translate on the surface in horizontal movements.
These latter exhibit however not a steady state nor any regular (f.ex periodic) dynamics - plates stop, reverse , continents break up, combine etc.
Just imagine that a giant molten plume that started to rise 50 millions of years ago breaks to the surface in the middle of N.America - this would cut America in 2 and create a new plate which would start to move in some direction and create new oceans/mountains.

From that follows that for all practical purposes the plate movement on the surface may be considered random (on time scales of several millions of years).
So now to get a frontal collision between 2 plates it is necessary that the velocity vector is in a quite narrow angle range (f.ex 45° +/- 5°) otherwise, as Chick said, the plates would slide and not collide.
Obviously the probability that this happens is 10/360 = 1/36 what is pretty small.
When one further considers that there are more oceans than continents on Earth and that one has to exclude ocean/continent plate collisions because those subduct, the probability is even smaller.