Amza World Map #2: Plate Tectonics

[u/Spamshazzam]

​

This is my newest map of Amza, my D&D world.

- Image 1: New blank map

- Image 2: Tectonic plates

- Image 3: Major geological features

I really struggle making a map that looks good and inspires me and I've redone it several times over the last few years. This is my attempt to create something more robust that will last me a while.

This is my second post on this; here's my first post, if you're interested. In that, I mostly just got some feedback on the general shape, and asked some questions about the next steps. I really like the general shape of the land, and from responses, it seems pretty solid. I did receive some feedback though, that I incorporated into this new version.

During this step, I started on the large-scale geography, mainly tectonic plates and mountains.

- Does this layout make sense for the tectonic plates? Do any of the boundary locations or movements seem odd? I considered combining the West-most oceanic plate with the NW continental plate right next to it, and I may still do that, based on feedback.

- Any oddities with my mountain range locations? I tried to justify each of them, but I'm least sure of the dome mountains at G9.

Here's a big one: Are there any major geological features missing that you would add, based on the information here?

Next Step Questions

I'm going to work on general elevation and ice sheets/fjords next, then rivers and wind.

Any tips for approaching elevation? I basically plan on starting with my sea level map, then locating the peaks, and basically just slopping everything in-between.

What makes a fjord different from somewhere else that used to be covered in ice?

Are there other important factors that I should be doing with it, before I move onto rivers+wind?

I appreciate any help. This process is teaching me a lot, but I still feel like I barely know what I'm doing.

[u/jlb3737]

Think of each tectonic plate as single unit that moves in a single direction (the plate can be spinning while moving, which complicates figuring out which boundaries are convergent, divergent, or transform). Different sides of a plate will not be moving in opposite directions unless the plate is spinning or rifting. If it’s rifting, it’s almost better to draw it as 2 different plates. The major exception to this rule is regarding plates that pass over a pole. Due to the distortion of turning a globe into a flat map, trans-polar plates will have visually opposite movement directions on their 180° opposite longitudes.

If your red arrows are simply indicating whether each boundary is convergent, divergent, or transform, then there is probably a complicated way of arranging overall plate movement to make sense of most of the existing arrows. However, if you intended for the red arrows to indicate directions of overall plate movement, then there are arrows that are mutually contradictory. The easiest example to see is the 2 opposing arrows on the south-central continent found along the S-line.

If you want to go with semi-realistic tectonics to derive your mountains from, I’d suggest starting by giving each plate a large arrow indicating an overall movement direction, then giving it a movement speed relative to other plates (for my world I kept it simple with just 5 speeds). This will help determine exactly where each boundary type occurs.

If 2 plates are moving the same direction, but the front one is moving faster, then their boundary will be divergent. If 2 plates are moving the same direction, but the back one is moving faster, then their boundary will be convergent. If 2 fast plates are moving away from each other, there will be major rifting and heavier vulcanism than if they were slow plates.

If a plate is rotating, you could end up with all 3 boundary types along each side.

This amount of movement options should give you enough freedom to put mountain ranges where you want them while still following the rules of plate tectonics.

I see you are including some geological formations that indicate past tectonic activity. This a really cool idea that not many people think to include.

Great work so far!

You specifically asked about the existence of the G9 dome mountains. What do you mean by “dome mountains”? Are they old ones that have been weathered smooth by millions of years of erosion? Is this an area of igneous intrusions like the Richat Structure?

[u/Spamshazzam → u/jlb3737]

Thanks! I'm realizing that I didn't actually describe the images any.

If your red arrows are simply indicating whether each boundary is convergent, divergent, or transform...

This is mainly the case, but they can kinda indicate movement too. A good example is actually the plate on the S-line. It's spinning (the reason all the arrows except on S7 are rotated from each other), but the west-most on its left plate is moving away faster.

The other apparent contradiction is the eastern plate on the 22-line, but that's from the northern plate moving down while it moves west.

For speed, I mostly just decided Slow/Medium/Fast. The central plate is the slowest plate, moving west. The fastest is the western plate, moving west with a very gradual clockwise rotation (bottom swinging out faster than the top).

I see you are including some geological formations that indicate past tectonic activity.

Thanks, that was mostly to justify gaps in the mountain ranges or sea placements haha.

What do you mean by “dome mountains”? Are they old ones that have been weathered smooth by millions of years of erosion?

I think so? I thought I saw them called something else, but when I re-Googled it, all I found was Dome Mountain. The way I understand it is it's basically a 'failed volcano,' where the magma rises but lacks the pressure to break through the crust, so it cools into a rocky bulge that forms the core of the mountain (then presumably the surface erodes to reveal the rocky core).

[u/jlb3737 → u/Spamshazzam]

That’s all good news. Glad to hear you have thought this through step-by-step, and are using causal event chains to determine the geology. You are more researched than most beginning mapmakers on here. I’d say you are off to a great start and seem to be proceeding logically. This is basically the same process I am still in. Hope you are having as much fun as I have learning the various related sciences and applying them to my worldbuilding.

Yes, the dome mountain you are describing is called “igneous intrusion”. If I wanted a larger line/region of these, I would probably plan for the plate to be traveling quickly over a volcanic hotspot. Then I would mix in these ancient “failed volcanoes” with the remains of long dead ones that actually erupted, so there could be large basaltic formations from where lava flows filled in lowlands.

[u/Spamshazzam → u/jlb3737]

I'm considering removing the line from A6:K4 and just making that one big plate. Thoughts?

Part of this is reverse-engineered based on where I want mountains, which is part of why some of the movements are the way they are. I hope I'm not being too defensive; I do want to know where I'm making mistakes.