[WIP] World of Aduhr

[Charerg]

On another tangent, since I haven't had the motivation to finish the river modifications (still at about 50%), I decided to re-visit the world's "palaeogeography" and I've been thinking how past movements of the continents would have affected their flora and fauna.

I don't plan to introduce any fantasy species into the natural flora and fauna, although several extinct species may end up being resurrected, depending on how the final results turn out regarding my "evolution model". Essentially the plan is that the evolutionary relationships of various animal groups should be the same on Aduhr as they are on Earth. So, some continent might end up having Australia-like fauna with Monotremes and Marsupials, while another might have something like pre-Great American Interchange South America.

For sake of simplicity I'll assume that overall the fauna and flora resemble present day Earth, and only relatively recently extinct species (say, extinct within the last 5 million years) have a chance of existing on present-day Aduhr.

To begin with, I'll concentrate on the evolution of mammals, since they're probably the most important group to consider (as reptiles are relatively similar between various continents, and birds can basically migrate anywhere via flying). So, the basic division of mammals that occurred during the Mesozoic era is the division into Monotremes (platypus and echidna), Metatheria (marsupials and related groups) and Eutheria (ancestral to placental mammals).

We don't know for certain when true placental mammals emerged (around 100 Mya might be a decent estimate), and in general the early evolution of placental mammals and the exact relationships of various groups remains a somewhat disputed question, but there is a consensus regarding their classification into 3 major groups: Xenarthra (South America), Afrotheria (Africa) and Boreoeutheria (Eurasia and North America).

So, as each of these three major groups of placental mammals evolved on separate continents, it's logical that a similar process would occur on Aduhr as well. Interestingly, Xenarthra evolved alongside true Marsupials in South America.

With this in mind, I thought to update Aduhr's palaeogeography a little. Unfortunately, I was unable to get GPlates to work (since I updated to Windows10, apparently GPlates is incompatible with it ). So, any updates regarding the tectonic history and modelling of past continental drift will have to wait.

However, I do still have the maps produced with my old tectonic model. As I mentioned, they are a bit outdated, since I have since defined the extent of the continental crust and made a few small additions, but I guess they'll have to do.

As I don't recall if I posted this before, this is the final version of the "present day" world map, including the continental crust:


A Mollweide projection of Aduhr 100 Mya (map via GPlates):


And finally a bit more refined version of "Palaeo-Aduhr", based on the GPlates map. This includes my first concept of where the main mammal groups (Monotremata, Metatheria and Eutheria) lived on Aduhr ca. 100 Mya:


Ok, that ended up being a bit more substantial than I originally planned for a "tangent project". Anyway, I hope someone finds this interesting!


EDIT:
Btw, the "100 Mya" maps are centered on 60° E Longitude (in order to have no continents "lining the borders"). So, they're essentially offset when compared to the map of "present-day" Aduhr.

[Charerg]

Ok, I went and downgraded my laptop (since it isn't my primary computer) back into Windows 8, and refined the plate tectonic model. I didn't touch the plates themselves (since I'm definitely not re-doing the tectonics at this point!), but the model now extends further back in time, into the actual "Pangaea" stage, and also I adjusted the dates of various collisions. I'll probably post some slightly more refined versions (like in my previous post) of Palaeo-Aduhr at some point, but in the meantime here are some of the new GPlates maps.

200 mya (Pangaea, or "Ur-Aduhr", as I like to call the supercontinent):


150 mya (Ur-Aduhr breaks into three major pieces):


100 mya:


50 mya:


10 mya:


I might have to revisit some of my hotspot-formed island chains since the continental movements are a bit different in the new model. In particular the long island chain attached to Urgaleon (the polar continent) might need adjustment, as the Urgaleon-Eocidar collision occurred at a speed comparable to India-Asia on Earth, and it might be nice to have similar "long trails" of islands as the Indian plate has to show off this piece of tectonic history.

Note: I kept some of the minor continental plates in place as "landmarks" to save some unnecessary work. I envision their tectonic history as basically the same as it was in the previous version of the tectonic model (covered in post #15).

[Diamond]

Man, I really admire your dedication into diving deep into the background of your world! World-building at its finest.

[Charerg]

Man, I really admire your dedication into diving deep into the background of your world! World-building at its finest.

Probably the best thing about this is, that in end you learn a lot of new stuff regarding Earth itself! About a year ago I had basically no clue how this tectonics stuff or the climate worked, but if you're put to the task of sort of "re-imagining" how the climate or the tectonics would turn up on another planet, it really drives you into delving deep into the subject (and learning about the base mechanics behind those phenomena).

[Charerg]

Well, it's been a while since my last update. I haven't done much mapping lately, but I did update the "main worldmap" about a month ago, so I guess I might post the new version:



The hot-spot formed island chains have been re-oriented to suit the updated tectonic model, and I also decided to change some of the submerged continental crust in the northern part of the map into actual land. Also, the mountain chains have undergone a few revisions, as well as some areas of Central Eocidar (the western continent). In particular, the lakes were changed a little so they make more sense. There's also a "Lake Chad" added into the interior (a large, very shallow lake in an endorheic basin).

Oh, and the dark green (0-10 m) areas in the far north depict (below ocean level) areas covered by the polar ice sheet.

[Ilanthar]

It's looking good Charerg!

[kacey]

I'm envious of this, you've put so much into it, I would never have the patients to work out all those details. It's really great, the map's look good.

[Charerg]

Well, it's been a long while since my latest update (I always start my posts here with that phrase, don't I?).

However, I've recently been working on a major update on Aduhr. This one started out as an attempt to build up a more refined topographic map and re-do the climates to suit it (yup, I really like the climate stuff). You could say that Tiluchi's recent work on Ayesha has been a big inspiration (as well as Pixie's Maward with its highly realistic-looking topography). My initial plan was to do this on a continent-by-continent basis, with maybe a week or two of time spent per continent (and take a month or two off between the continents, since I do have some non-mapping related projects going on that need to be worked on as well).

To make a long story short, the project snowballed into a far more comprehensive overhaul than I originally planned (as is often the case with my projects). I did a lot of research about the geologic history of various parts of Earth, in order to have a better idea of what each mountain range should look like, and in the end I ended up doing a major overhaul of both the tectonics and the coastlines (as the previous tectonic model didn't really work with the Wilson Cycle).

So, I guess this is the "hardcore version" of the tectonics. Here's what the new version looks like 200 Mya:



As you probably notice, the big change is that I moved into a 2-supercontinent model (presumably these two were once a single continent and have since drifted apart), with most of the continent blocks forming the equatorial supercontinent (called "Panwara"), and a much smaller continent sitting on the North Pole (as yet unnamed, but let's give it the original name of "Polaris", based on the location).

Here's the situation 50 million years later, 150 Mya:



The map shows how Panwara first separates into western and eastern portions. Presumably the driving force behind the dispersal is the subduction of a mid-oceanic ridge by Polaris (comparable to subduction of the Tethys ridge by Eurasia), causing a new rift to form. A major change between the new model and the old one is visible in the position of Akanrias (the southern part of Eocidar, the large western continent). The previous model envisioned Akanrias separating from Central Eocidar via a sort of hinge-type rotation. However, in this particular situation, I could not find a good tectonic justification for that type of breakup, and I ended up scrapping it. Instead, the new tectonic model envisions a large area of extended crust formed between Akanrias and the rest of Eocidar by a system of failed rifts that was active during the initial breakup of Panwara.

And the next stage, 100 Mya:



Here, the northern continent (Polaris) has also begun to break. Again, the cause is envisioned as the subduction of a mid-oceanic ridge by Eocidar, causing a new rift to form between Urgaleon (the northernmost continent) and Rheada. However, clearly more of the Tethys-like ridge has also been subducted by Polaris, since now the Valkathaic rift has expanded northwards (Valkathain is the "Inner Ocean" of Aduhr). The large archipelago of Meias has separated from Central Eocidar (after which the rift shifted northwards), and the eastern continent of Anapar (the one with a similar shape to Australia) is also breaking apart.

50 Mya:


There's not too much new happening here. There's an oncoming collision between Neraduhr and several island arcs, and the Khaer islands are starting to separate from Rheada as part of that process. Another major development is that the Trans-Eocidarian Rift begins to form, creating a large rift valley separating Northern Eocidar (called Menorias) from the central parts of the continent. Ofc there are a lot of finer details that I could cover (and not necessarily everything has been included in the GPlates model), but I think I'll save those details for the "present-day topography" updates.

And finally, here's the present-day situation:



In this map, I've included a rough approximation of the ages of oceanic crust based on that little model I did with GPlates (you probably noticed those pieces of new crust appearing in the previous maps). However, I should note that some of this based on guesswork (in some cases I also shifted the ridges from the GPlates version, changing my mind), so it's fairly unpolished and there are some weird areas here and there.

Another major caveat is that the plates of the Outer Ocean (Agalhain) are pure guesswork at this point. All I can say for certain is that there's definitely a triple junction there somewhere separating the Urgaleonic plate in the north from the eastern and western halves of the Agalhaic plate. Here, I've depicted the "main ridge" as largely subducted beneath Eocidar, but this is just a pure guess. On Earth, the history of the Pacific is actually quite complicated. As an example, here's a reconstruction of the Age of Oceanic Crust ca. 80 Mya (from this site):



There are as many as four plates (Izanagi, Kula, Farallon, Phoenix) that once formed a portion of the Pacific and have now been subducted. To make matters more complicated, the exact location of the ridges also has a great deal of relevance to the whole process of supercontinental breakup (as the primary cause was the subduction of a mid-oceanic ridge). This is especially true in my case, since I have convergent continental boundaries in two places (northern Eocidar and southern Rheada), which indicates that two mid-oceanic ridges must have been subducted (instead of just one, as was the case on Earth). So, all in all, I've decided to save the "Agalhaic puzzle" for a later date. I had enough of a headache just figuring out the dispersal of the supercontinent(s), without going into all those subducted plates!

So, that's it for this preview. Next up, I'll continue work on the elevations of Eocidar (which I fortunately almost finished before I decided to overhaul the tectonics, so shouldn't take too long). I guess I might post a more traditional map of the tectonic plates as well, although the boundaries are visible on the Age of Oceanic Lithosphere map (and it's pretty easy to guess the locations of active ridges from that ).

[Pixie]

Charerg, I wish I had more time to write up a proper comment. Something inteligent, with suggestions, praise and general comments. But I don't want you to continue unanswered in this thread, so here goes an sms sort of comment:

I'm envious! I wish I had your skills with g.plates. To me, this is beautiful. Congratulations!

[Charerg]

Right, so I've finally gotten at least a piece of Eocidar into a more-or-less finished state. I should probably mention that I've basically overhauled most of the elevation map from what I had back in February when I made that ill-advised statement that "it will done soon".

I might post something about the geologic features underlying the sub-continent at a later point, but since I'm feeling a bit lazy that will have to wait. However, here's the elevation map for the sub-continent of Akanrias, the southernmost of the three pieces that make up the continent as a whole. I should note that the bathymetry is pretty rough at this point, since the focus is on the topography, and there will probably be some changes to some of the continents and the associated tectonic features (exact location of the ridges and what-not). I've shelved that update for a later date though, for the moment I'm just focusing on this particular continent. So, here's the map:



Within the global map, here's the location and size of the area depicted here:



And finally, for purposes of comparison, a map of the Earth using the same elevation scheme and intervals (this is generated from the ETOPO1 global relief model, using the "ice surface" version, note that the glaciers are not coloured separately, but are instead regarded as part of the surface):



The colour scheme is still a bit WIP, though I'm pretty happy with the lower elevation levels. However, I'm not sure if the dark brown->white transition with the higher levels is all that good right now. So, any feedback on the colour scheme is appreciated.

Anyway, that's it for this update. Any comments/suggestions are welcome as usual, and I'll try to post the relevant geology and tectonics regarding Akanrias at a later date.