Tectonic plates and mountains (I have no idea what Im doing!)

[gyldenstern]

I figured I could just as well start from scratch with my world map. If you notice a resemblence with the real world its intentinal. What you see here is a modified version of europe, the middle east, northern africa, Ucraine, Russia (and so on).

So, I dont pretend to be a geologist, but I want my world to have a real feel about it. And I want my world to be a bit more geologically dramatic (if that makes sense ) than our real counterpart, with huge mountain ranges in "spain" and active volcanos in "german", and so on.

Am I on the right track? The red lines are the tectonic plates and their movement, yellow are volcanos (more or less active) and the orange looking strokes are mountain ranges.

What should be my next step?

[Azélor]

If you want volcanoes, you need to have convergent plates. This is where they are the most likely to form. Ideally it would need to be with 1 oceanic plate and 1 continental plate but it's not a necessity.

Convergent and transforming boundaries will generate mountains but mountains tend to be higher with convergence, I think.

[Chick]

Volcanoes (stratovolcano types only) will be common on converging oceanic plate under continental plate. Think the "ring of fire" around the Pacific Ocean. They can also happen where two oceanic plates converge, forming chains of volcanic islands.

Very high mountains will be common on converging continental plates. Think the Himalayas where India is running into Asia.

Transform boundaries do not generate volcanoes, and not even mountains unless there is some angle of continent-continent convergence occurring.

Shield volcanoes happen over hotspots where magma from deep in the mantle is rising in a single spot. Think Hawaii. As a tectonic plate moves across that hotspot, a line of volcanoes can form, but the only active one is the one on the hotspot. The rest are extinct after they move off the hotspot. Think the Emperor Seamount Chain which are the extinct volcanoes from the Hawaii hotspot.

[Adversary]

I have a (Very) crude picture of a subduction zone in cross section.

This is an oceanic plate subducting under a continental plate. As the oceanic plate sinks it pulls some water and granitic continental crust with it. The rest gets scraped off in the accretionary prism. The water acts as a catalyst that lowers the melting temperature for the surrounding rock. This is necessary because otherwise, as the magma moved upward the temperature drop would solidify the rock before it reached the surface. The key is that the volcanoes are only on the over-riding plate and are quite far away from the actual subduction zone. Look at the Pacific rim and the Ring of Fire. The trench east of Japan is the actual subduction zone. The volcanoes are... well... Japan.


Volcanoes are not common on a continent/continent subduction zone (Think Himalayas). But if you have a convergent boundary you will have ridges paralleling the rift (red line on the photo, and volcanoes along/near the rift (upper right of the photo)

[Adversary]

Mountains formed by the collision of two plates (like the Appalachian mountains) will have the mountains raised parallel to the impact faces and perpendicular to the motion. Behind the mountains the land will be folded (valley and ridge).



The coastal plains are formed from the erosion of the mountains. The Appalachians were formed by the collision between Gondwanaland and Laurentia creating Pangaea. At their height, the Appalachians would have rivaled the Himalayas. This is a simplistic explanation there are a lot of other things going on in the creation of the mountains and the valley and ridge (The valley and ridge are actually the weathered remains of the original folds), but I hope this helps out.

[johnvanvliet]

there are some software models here
Model download portal - csdms
-Terrestrial-
Terrestrial models - csdms

[gyldenstern]

Great, thanks! The more I study this the less I understand, it seems. However, I think I know enough. Im no geologist, and I never will be and this is way over my head. But I think the map will turn out quite realistic. At least theres no Mordor!

On the other hand, a magical fantasy world where theres gods, dragons and extra cosmic horrors might affect the landscamp in a myriad of unholy ways

[gyldenstern]

New plates. How does it look? Plausible?


(Edit: Im aware that the mountains look like s**t. Working on that )

[Adversary]

This looks better. If you reverse the motion on the south western plate to move south, you can have a mid ocean ridge with the ocean getting larger. By eliminating the gumdrop shaped plate you could have a subduction zone with the sea becoming a trench and the mountains north of it would be a volcanic arc. It is not necessary to have the western plate move east. It could also move west and the mountains came from a past collision (like the Appalachian mountains). The south central plate could also be moving north, just at a slower rate than the south western plate. Again that would continue the volcanic arc of the whole central mountain range.

But it is your world so you could have a continent/continent conversion that would form mountains like the Himalayas. With the exception of the 90 degree branches off the mountain ranges the mountains make sense to me.

Looking good.

[gyldenstern]

Thanks. This is more or less the final map:

Couldnt have done it without you!

Edit: but please comment if anyting looks weird.
The rivers are just a test. Ill redraw those.