[WIP] World of Aduhr

[LowerSpatialDimension]

First off, I'm incredibly impressed by these maps; the amount of research, skill,artistry and effort that's going into them is truly inspiring! However, I'm getting hung up on one aspect that's causing me trouble myself, and that's scale. The shape and realism of your mountains are incredible, but to my eye they look like regional (aka small-scale) mountains, such as could be crossed in a day or two of hiking. Given the scale of your world I would guess that these mountains are meant to be much larger, approximating entire mountain ranges like the Rockies or Himalayas. However, at those scales mountain ranges look much different than the ones you've illustrated; they look more like clusters of noise, and individual ridges are impossible to discern. I've uploaded a couple images to demonstrate what I'm seeing:





With that in mind, a few questions:

A - Am I misinterpreting the scale of your map?

B - If not, did you choose to represent your mountains as you did for artistic reasons?

Or,

C - Did you choose to represent them as you did because the tools you're using (Photoshop, Wilbur), don't allow for that level of detail and resolution?

I ask because, as I set out on my own mapmaking journey, I want to make sure that I get the scale of my mountains right before spending many hours fleshing out the height maps. However, I'm also pretty inexperienced with Wilbur so I want to make sure I don't work on a scale that the program can't handle.

[Charerg]

@LowerSpatialDimension:
You are correct with the scale, these are indeed vast continental-scale mountain ranges. I suppose the ridges being a bit pronounced in places is more of a result of the artistic process than anything else (after all, I'm also human, so these aren't 100% realistic of course ). It's also a conscious choice in the sense that I intentionally work at relatively low resolutions, so I'm not necessarily aiming for extreme detail in these global-scale maps (that is better kept for regional maps).

Though Wilbur does have trouble with high resolution images (it can still handle maybe 4000x2000 pretty comfortably, for example), so if you intend to use Wilbur it's a good idea to keep that in mind (though myself I haven't found it a hindrance).

Edit:
Btw, I calculated the average elevation for C. Eocidar and ended up at about 720 metres, falling about halfway between Asia (915 m) and Africa (580 m).

[Charerg]

So, I mentioned I would post something about the geologic history of C. Eocidar's western mountain belts (dubbed the "Eocidarian Cordillera" since they're mostly inspired by the real-world mountains of that name). I actually have a fair bit worked out for how various parts of the mountain range formed, ranging from different terranes docking with Eocidar to subduction of submarine plateaus. But since I keep most notes in my head it's all a bit disorganized, and this post ended up being mostly about the history of the C'thuana terrane, so I guess I'll call this post "part one" on this topic.

With the intro out of the way, let's dive in and take a look at Aduhr 200 Mya:

Needless to say, this is all very WIP still and the further back in time we go, the less detailed things become. But at present the C'thuana terrane is envisioned as originating from the southern margins of Panwara, diverging at about 250 Mya. The main reason for the divergence is the NW movement of Panwara: there is a retreating subduction zone on the southward margin of the continent, and this causes the C'thuana block to break off. Overall, a similar process to what went on with Japan diverging from mainland Asia, or Stikinia from Laurentia for an even better example.

Next up, a few screenshots from the ages 150 and 100 Mya:


At 150 Mya, it can be seen how Panwara begins to break up, and the subduction zone south of the supercontinent has shifted into rapid advance from its former state. This cause a new subduction zone to form at the southern margins of Nomune (the southernmost piece), subducting the now-quite-aged crust of the "C'thuana Sea". At 100 Mya, the mid-oceanic ridge is subducted and the C'thuana Plate itself falls under slab pull, beginning to once again converge with Eocidar.

Finally, here's a look at Eocidar 50 Mya:

Here, the C'thuana terrane is on the verge of colliding with Eocidar, a process that will eventually close off the western interior sea. To the north of the continent, the collision between Urgaleon and Eocidar is proceeding, which will result in the opening of the Trans-Eocidarian Rift, breaking the continent in two (the epeirogenic uplift, normal faulting and flood basalts released as part of this process will close off the eastern interior sea). Besides the C'thuana terrane, there are also two smaller terranes (K'wira and T'kalo) that have been accredited to Eocidar at a later date than C'thuana. As their exact movements remain a bit in flux, I decided not to go in too deep about those just yet (maybe in future if I ever complete the tectonic model for that Indonesia-like region SW of Eocidar).

And with that, I think we can close off "part one". The next part will discuss the northern portions of the cordillera and how they acquired their present-day structure.

[HandwaviumAdAbsurdum]

I came across this project a few days back and I was taken aback. I have never before come across a worldbuilding project which has put this much emphasis on geological plausibility. All the time you've spent refining your plate motion model in gplates has really paid off. Much of your topology looks very convincing, and is testament to the astounding level of research and study you've put into this project. For example, the concave shape of the Eocidarian Cordillera is very reminiscent of the Bolivian Orocline, both in terms of its curvature and its elevation, and I can see how they very well might have shared a similar tectonic evolution. I also have to say that the basin and range topography at the northeastern end of the Great Akanrian Trough is absolutely inspired.

If I have one criticism, however, it would be that your rift systems are maybe a bit too linear. You have these unbroken, gently curving lines, when what one would expect lots of smaller unconnected rift basins following a general axis of extension. In some areas you might even have multiple rift basins running parellel to each other.

This criticism does not apply to the Great Akanrian Trough which has clearly reached a far more advanced stage of extension. The width of the trough suggests to me that it should be mostly submerged, and may have begun seafloor spreading at its widest portions before becoming inactive. The remainder would have reached a transitional stage with a thin veneer of continental lithosphere. After this one would expect a degree of postrift subsidence of not just the trough itself, but also the flanking horsts. Then we need to take into account 140 million years of sediment being deposited, but even then I still think it would be more reasonable for more of the trough to be submerged. What I have in mind is something along the lines of the Bay of Fundy, at least for the southwestern part of the trough, getting progressively deeper as the trough widens. At northeasterns portion, I'm thinking something more along the lines of the Mozambique Channel or Davis Strait, with oceanic lithosphere overlain by thick sediment.

Speaking now from more of a geopolitical point of view, this alternative setup would have some interesting implications. Two strategically important locations would emerge: one south of the Ilanga fault blocks where we already see something very reminscent of the Strait of Hormuz. This narrowing of the gulf serves as not only a viable crossing point but also a vital choke point, where shipping going in and out of the gulf can be controlled. A longer gulf would only increase the strategic importance of this choke point. There would also now be a narrow land route between the southwestern end of the gulf and the ocean which would serve as a narrow isthmus connecting Akanrias with the rest of the continent, very much akin to the Isthmus of Suez connecting Africa and Eurasia. To me, at least, this would be a desirable consequence, but if it isn't to you then you could explain the current topography of the region by having this area move over a hotspot and causing uplift that way.

Keep up the good work. I'll be following this project eagerly!

[Charerg]

@ HandwaviumAdAbsurdum:
Making more of the Akanrian Through submerged is something I considered at one point, and even made a sketch of how it would look like. However, I wasn't too happy with the overall look, so I ultimately decided against it (largely on aesthetic grounds admittedly). In geologic terms the trough definitely should be deeper than it is. My main explanation for the abnormally high elevations of the Akanrian Trough (as well as many other cases in C. Eocidar) is that the continent is undergoing active rifting and I envision something like the African Superplume causing major epeirogenic uplift (more or less the "hotspot explanation"). The feedback is still much appreciated, though (and who knows, perhaps I will change my mind at some point) .

The Trans-Eocidarian Rift System turned out to be a pretty big headache for me (especially the central portions), with many revisions. The rift is envisioned to be more "mature" along the western parts, while the eastern part is somewhat less developed, with a major strike-slip component. But I definitely see your point here, the rift system could surely be a bit more complicated in structure. After I've finished the remaining parts of the continent, I'll probably do a bit of touch-up on the previously completed portions (C. Eocidar and Akanrias), so this is something I'll probably revisit in the future.

[Charerg]

As a bit of a status update on the project, I've mostly been working on updating the coastline of Menorias (northern portion of Eocidar), but not quite finished with that. However, I did get sidetracked a bit and ended up working on the long-planned update on Akanrias. There's been some adjustment of the coastlines and elevations, incorporating most of the feedback received on the subcontinent (the Ingilo region is much "flatter" now and in general elevations have been toned down a bit in the older, heavily eroded portions of the subcontinent). I also reworked the Great Akanrian Trough a bit, so a greater portion is now submerged. Another area that received a major update is the East Akanrian Fault Complex (EAFC), which has been realigned and repositioned to match the updated tectonic model. As a part of this update, the eastern fold belts have also been adjusted.

I thought it might be interesting to compare the subcontinent back in 2018 when I first started to work on the greyscale elevation map with the current iteration:


I must admit that I shudder a bit to look at the older version of Aduhr, which is probably a good sign (since it means there's been progress ). So although the elevation map is a very time consuming project, one can't help but feel a degree of satisfaction when looking at the difference between the two maps (that is, before everyone posts that they actually prefer the old version). Anyway, that's it for this update, comments are welcome as usual, and hopefully I'll have an update on Menorias in the not-too-far-out future.

Edit:
Apparently I drew the EAFC as a dextral (right-lateral) transform fault here (it should actually be sinistral like in the original map of the tectonic features).

[Charerg]

As another status update, I've now finished redoing the coastlines of Menorias (northern portion of Eocidar). I realised I haven't posted the world map in a while, which has undergone some major changes since its previous iteration. So I thought this might be a good time for that:



The southeastern region has been basically compeletely redone (and as can be seen here, the shapes and coastlines are still WIP in those areas). A new micro-continent (Balarr) has also been added with a somewhat uncertain tectonic history. As far as the rest of the map goes, Nemeias is largely finished, apart from some final touch-up in a few places, and I'll probably update the coastlines of the polar continents after the elevations for Menorias are done. Still a lot left to work on, but with most of Eocidar now finished, it doesn't look quite as daunting anymore .

[MrBragg]

Wow, those are some big changes! Did you have to majorly revise your tectonic model to accommodate all that?

The elevation maps for Eocidar, Menorias, and Akanrias look absolutely fantastic--looking forward to seeing the evolution of the other regions

[Charerg]

It is impressive. How will u think work with northen and southen poles?

The same way I work on basically everything beyond the 30 N/S latitudes: reproject the area to equirectangular oblique centered on the region I'm working on, then project back to equirectangular once finished. I've found that this method removes most of the projection-induced inaccuracies, while it's easy to project the eq. oblique back to regular equirectangular. For example, here's Menorias projected to eq. oblique (centered on -90 E° and 35 N°), and clipped from the world map:

Wow, those are some big changes! Did you have to majorly revise your tectonic model to accommodate all that?

The elevation maps for Eocidar, Menorias, and Akanrias look absolutely fantastic--looking forward to seeing the evolution of the other regions

I did update the tectonic model a while back, though at that point I already had most of the revisions in mind, so in a sense I didn't have to change the tectonics (since I already built the tectonic model to represent the updated map before redrawing the coastlines). I guess my latest tectonics overview has become quite outdated, and I should probably post an updated one at some point. Though most of the plate movements remain similar, just more refined and with more of the details worked out. I guess the big change is that Anapar, which used to be a continent, has now collided with Nemeias (forming that large horn-shaped peninsula). Instead of Anapar I now have the aforementioned Balarr as a new micro-continent in the SE quadrant of the world map, however Balarr will have a different tectonic origin (and that hasn't really been defined yet). Here's how the tectonic model (so far) looks at 0 Ma (not quite up-to-date when it comes to position of Balarr and the coastline of eastern Nomune):



And as an example of some of the details, here's Nomune at 50 and 20 Ma, respectively. I used to have the minor sea opening between the island of K'yatahi and mainland Akanrias at ca. 300 Ma, but in the updated tectonic model it makes more sense that this is a recent event. The continent of Nomune changes direction from a southern vector to a more southwesterly course at 50 Mya, and as part of this movement, K'yatahi detaches from Akanrias. This is actually something that isn't reflected in the topography yet (since the mountains surrounding the sea would be expected to be taller now that they've been formed much more recently).

[Harrg]

It is impressive. How will u think work with northen and southen poles?