Mapping an Earthlike planet

[Akubra]

Thanks groovey! There are also some areas that can be improved though, such as the subduction zone east of Eneaga, the northern continent in the centre. The subduction zone starts near the base of the peninsula pointing eastwards. I think the continental shelf should be hugging the peninsula's coast more than it does now. And maybe I should add a little shelf south of the subduction zone too. Right now it looks just the opposite of what it should be.

Cheers - Akubra

[Akubra]

OK, here's another update, and a rather long one.

1. What's an 'Earthlike planet'?
A few days ago I was thinking: "When I talk abaut Rautah I want to be more precise than saying it's an 'Earthlike planet'." So I sat down, did some research, started calculating and after a few hours came up with these numbers:

• Radius (eq.): 7 353 km (1.154 times Earth) (I'm not yet sure about the polar radius)
• Equator length: 46 199 km (1.153 E)
• Area: 679 384 087 km² (1.332 E) (calculated for a perfect sphere)

• Tropics: 22° 09' 19.6" [22.155°] (a little south of Earth's tropics)
• Polar circles: 67° 50' 40.4" [67.845°] (a little north of Earth's polar circles)

• Volume: 1.665 x 10^12 km (1.537 E)
• Mass: 7.677 x 10^24 kg (1.285 E)
• Density: 4.611 g/cm³ (0.836 E) (less than Earth to compensate for its larger volume and still have a comparable surface gravity)
• Gravity: 9.477 m/s² (0.967 E)

• Length of day: 24h 19m 11s [24.320 Earth hours] (1.013 E)

If you spot any inconsistencies or outright impossibilities, feel free to point them out.

2. Tectonics revisited
When I saw Pixie's latest tectonics map I told him I was jealous. So I had another look at mine. I thought it was OK, but I also wanted to have some more interesting areas. Of course I didn't want to imitate Pixie, but his map made me try a few things with mine. The result is below. I added a few smaller plates, broke up some others and made some adjustments to their movements and the continental shelves. Be my guest to comment. I just hope I didn't make a mess of it...



3. Taboran revisited
In my very first post on CG I told about Taboran, the very first continent I had imagined. I was almost certain that somewhere I still had a crude drawing of it on graph paper. So I started searching in some boxes that were tucked away in hard-to-reach corners. It didn't even take too long before I could exclaim: "Lo and behold!" I quickly scanned it and gave Taboran a place on the planet Rautah. I downgraded it to an island, because its original size as a continent would have been too large to fit. You can find it on the eastern boundary of the eponimously named tectonic plate (one of the new plates). The island is created by Taboran plate colliding into Yirral plate. It does feel good to finally find a place for it

4. Windswept
I started with the preparations for a climate map, but it's going quite slowly, as I expected. I've come as far as the maps with the dominant winds. I'm not going to say too much about it, but let you judge. The first one is for the Northern winter / Southern summer (January), the second one for the Northern summer / Southern winter (July). On these maps the polar fronts and the ITCZ are straight lines (for the time being).



Thanks for having reached this point of my rant

Cheers - Akubra

[EDIT] I realize I haven't taken into account mountain ranges in the maps with the dominant winds. I have prepared a crude mountain ranges map which I will post tomorrow.

[Pixie]

Well, I'd like to say welcome to Taboran first. My childhood world also started with a smaller piece of land, it was a large island called Brania, so I totally relate.

Secondly, I like the way you strive for perfectionism. Each version is a thoughtful improvement on the previous one. Your changes and microplates did not make a mess. Yet, tectonics plausibility there's two details you are failing to address (I was too until recently):
- if you have the divergent boundary in an ocean unsymmetrical you normally explain the missing crust on one side with subduction (like pacific ridge vs. south america) - Akua plate you can get away as it is rather small, but for the boundaries east and west of Nohhon... hmm...
- when you change the curvature of oceanic subduction, you are changing which side is sinking

(alas, these details have no influence on the land masses or location of mountains, so - as always - you can choose to ignore them)

It seems like your weather maps are having (will have) more work done on them, so I'll wait for corrected versions - in the meanwhile, let me say that your H/L centers are visually very appealing.

[Akubra]

I like the way you strive for perfectionism. Each version is a thoughtful improvement on the previous one.

Thanks Pixie!

if you have the divergent boundary in an ocean unsymmetrical you normally explain the missing crust on one side with subduction (like pacific ridge vs. south america) - Akua plate you can get away as it is rather small, but for the boundaries east and west of Nohhon... hmm...

I understand. So what you are saying is that I should either change the location of the boundary, i.e. more towards the centre of the ocean, or change the nature of the boundary (which means changing the direction and/or velocity of the plates)? I'll see what I can do about it.

when you change the curvature of oceanic subduction, you are changing which side is sinking

I'll check my subduction zones against their counterparts on Earth.

Meanwhile, as promised yesterday, here is a rough outline of the mountain zones I'd like to have:



Blue: mountains being created by convergent boundaries
Red: volcanic zones (on land) created by divergent boundaries
Black: mountains created by past plate collisions (it looks like I have created a lot of coastal mountains...)

Cheers - Akubra

[groovey]

And I thought your tectonic map couldn't get better! But damn it did.

[Akubra]

Thanks a lot groovey! (Still got some work to do if you read Pixie's comment above... but hey, that's part of the deal).

Cheers - Akubra

[Akubra]

It's been a few days since my last post (been busy with other things).

I've tried to take into account Pixie's comments about tectonics and made the following changes:

• The boundary between East Nohhon and Eneaga plates has moved to the west, so that it lies more central in the ocean between the two continents.
• The boundary between Onuskia and East Nohhon plates has disappeared. I've created a new plate (Nohali) between the two of them. Nohali's western boundary lies roughly in the centre of the ocean between Ranineo and Nohhon. The southern portion of its eastern boundary is the same as the eastern boundary of Otia, a microplate that has disappeared. The northern portion is a new subduction zone creating a few islands to its east. I've managed not to perturb the existing ocean currents by these islands.
• Akua's western boundary is now more to the east, and I've created a new microplate (Sayali) lying between East Nohhon, Taikaram, Akua and Taboran plates.
• I don't know what to do about Pixie's second remark (changing the curvature of oceanic subduction). Where would the direction of subduction be wrong on this map?

Unless it contains something completely illogical, I'd like to leave the tectonic map roughly as it is now (save for a few minor corrections that can be done quickly).

I've also slightly adapted the position of Rautah's main mountain chains (blue = mountain building at convergent plates, red = volcanic activity at divergent plates, black = existing old mountain chains from previous tectonic activity). I'm going to take these mountains into account to create my dominant winds and climate maps. I don't think I will have the patience to puzzle them together like I did with the tectonics and ocean currents maps. I'm satisfied with an acceptable climate map without hot deserts at the poles or sea level ice fields at the equator .



Cheers - Akubra

[groovey]

Hello!

Seems most of us have gotten busy with other things lately! I hope to get back in track soon.

Anyway, what I think Pixie meant, because he's helped me with that on my map, is that on subduction boundaries, the side "eating" the other plate would usually have a convex oval shape, with the triangles pointing towards that side "eating" the other. Explaining it with words sometimes makes it more confusing, but well. For example, on your last tectonic map, the subduction boundary btw Eneaga and Sulina, Gathia and Taiunta plates; from Eneaga's point of view, the boundary has an "outward" or convex oval shape, so Eneaga should be "eating" Sulina and friends and the triangles should point the other way around.

That is, of course, if I didn't understand wrong, so I'd wait for confirmation from other more reliable sources.

The second image with the "outline" for mountains and volcanic activity is cool. I'll do something like that once I'm done with the tectonics (I'm very close), but adding seismic activity in yellow (if I'm able to spot it). Since the current orogeny and the volcanic activity are mostly determined by the tectonic map, there isn't much room for you to improvise or for us spot "mistakes". I do have two questions:

1. So it's assumed that where there are islands' chains of obvious volcanic origin there's also volcanic activity so it's not indicated, or you simply didn't need that info represented, just when it's from divergency?

2. Thankfully we are free to place old mountain ranges where we please, as long as it's not highly implausible, but one thing that catches my attention is you hardly have any of the old ones inland, they are mostly coastal. Not that there's anything wrong with that, but I'm just curious about it. For me it's a practical issue because I'll need many rivers to place settlements, and for example, in your Ranineo continent, they would have to rely in small mountain ranges and rainfall for "steady" water sources (like in the island I'm from before bottled water was a thing, we have no rivers here, and lack of water was a constant historical worry for thousands of years), perhaps just visible in regional maps, wouldn't they? Because rivers created by the old coastal mountains on your map would look for the easiest way to the coast. Or how would you solve the lack of big rivers inland in that continent? This is probably not something you are interested in anyway, but have you given any thought to it? I'm truly interested.

[Akubra]

Hi groovey, and thanks for your post. Sorry it took me a few days to respond.

I checked your explanation about the convex/concave subduction boundaries against a tectonic map of the Earth. Not surprisingly, I'm quite convinced that you are right. Thanks a lot for pointing that out! For some reason I missed seeing that. It also means that I should change some boundaries and island chains. Hopefully that will be the last major change.

Now your questions:

1. I could give you many reasons why I didn't indicate the volcanic activity caused by subduction... But the simple truth is, I just forgot it... I started with the divergent boundaries and then went on with the older mountains, missing the subduction boundaries entirely. Good that you spotted it!

2. The map's many coastal mountains are indeed something that's bothering me too. I don't exactly know why, but when choosing mountainous areas I feel drawn to the coasts. Maybe it's because of their shape: I seem to place the mountain chains on long peninsulas and long stretches of more or less straight coasts; somehow they feel natural there (not sure if that's true in reality). I really should give more thought to placing a few of them more to the centre of continents. As for your observation that rivers created by the old coastal mountains on your map would look for the easiest way to the coast, well, you're right of course, but the way a river is heading all depends on where it originates. Take the Amazon, which is one of the major rivers in the world. Its source lies much closer to the Pacific Ocean than to the Atlantic, yet it crosses the breadth of South America and discharges in the Atlantic, creating the enormous Amazon Basin and the most expansive rainforest in the world. True, its source is located in the Andes, which is not an old mountain range, but I think it would still be possible if the Andes were much older. That said, I do agree that I should have some mountains away from the coasts. If anything, it would make things more interesting.

Cheers - Akubra

[Pixie]

Hi folks.

Good thing groovey managed to explain to you how convex/concave works when subduction happens between oceanic plates. Looking at your map, I second you in identifying that as the single change that needs (needs is always a strong word...) to be done. Mainly at the boundaries between Eneaga and Sulina and between Eneaga and Yirral, but you could also revise the boundaries between Ranineo and Lomo.

Other than that, I'd be very happy with the result of your work.