halogen888

Latest Posts by halogen888

About a year ago I started working on my Retrograde Earth series, in which I depicted Earth's continents on a backwards-spinning Earth, which would result in a major reconfiguration of Earth's climate. The first map I made in this series was Retrograde South America; however, that map has aged a bit since then as I've learned more about mapmaking and received further input from u/AncalagonTheBlack42 and MolotovJack. This is my attempt to remake that map from scratch. My next project will be to stitch all of the maps I've made thus far into a global map and render it as a globe in Blender or some other program if I can get that to work.

I forgot to post the Retrograde Eurasia map back when I finished it in February. Since we’re looking primarily at Asia and Europe this time, this map is by far the largest out of the five I’ve done. For any further details on the climate check out:

 https://www.reddit.com/r/worldbuilding/comments/1bwp6hn/v5_retrogradeclockwise_earth_map_and_accompanying/ 

 https://www.deviantart.com/molotovjack/art/Retrograde-Earth-V5-Final-Version-985503973.

I’ve been wanting to do a detailed tilted Antarctica map for a while now, but the low resolution of the bedmaps up until now and the need to reconstruct pre-glaciation topography made me a bit apprehensive to start it. However, the recent release of bedmap3 to the public gave me the motivation to give it a shot. For this map I used the isostatic adjustment from Paxman et al. (2022) on bedmap3 to create a version accounting for isostatic rebound. I then used the rasters of Antarctica during the Eocene-Oligocene boundary from reconstructions made by Paxman et al. (2019) and tried my best to combine it with my rebounded bedmap3 map, in order to preserve the fidelity of the highlands and add the features which were lost to erosion. I took this heightmap and ran it through Wilbur to carve out valleys and rivers as well as to add more detail to the coasts and ease the transition between the two maps. I then used the topography and likely climate of the continent to create a false satellite map. Finally, I looked up the names for various features, both glacial and subglacial to fill out the map. I also used qgis to help convert between projections and do raster calculations for the rebounded map.

Description:

It’s difficult to picture Antarctica as anything else aside from the vast frozen expanse we see at the bottom of the world today, but as with everything involving deep time, our present is only a snapshot in Earth’s history. Up until the Late Eocene, Antarctica was as rich and varied as any other landmass. From what little we have of Antarctica’s fossil record, its makeup was broadly similar to Pre-interchange South America, home to early Ungulates and Marsupials as well as their close relatives. Antarctica’s habitats were equally diverse, hosting grasslands and even Austral forests, likely resembling the Valdivian rainforests of Southern Chile, with even palms being present during the Paleogene. However, as South America and Australia departed northwards, the circumpolar-Antarctic current took hold, restricting the flow of warm subtropical waters to the poles. This cooled the continent and its elevated interior allowed glaciers to easily take hold, thereby dooming nearly all of its inhabitants to extinction. 

But what if this wasn’t its fate? Let's imagine that over the course of the last 40-45 million years, Earth’s poles slowly change their positions, slowly enough that its disruption to Earth’s climate is about as gradual as the movement of the continents. By the present, the North Pole is over Africa, somewhere in Northeast Nigeria, and the south pole over the middle of the Pacific, adjacent to the Manihiki islands, which places Antarctica squarely in the Tropics with the new equator running through East Antarctica. The tilt chosen for this map is the same as Jaredia from the World Dream Bank’s Planetocopia, an old website which depicted alternate versions of Earth, as well as alien planets. For now, we won’t focus on the ramifications this has for the rest of the planet. 

Being covered in glaciers over the last 34 million years has dramatically altered Antarctica’s topography, not only has the land been isostatically depressed, but the movement of glaciers has eroded vast tracts of the continent. This version of Antarctica never underwent any kind of extensive glaciation, resulting in a landmass quite alien compared to the one we would get if we simply removed the glaciers from Antarctica now. The Northeast of Antarctica is now covered in tropical rainforests, likely filled with a diverse array of marsupials and birds. Things become slightly drier as we travel inland and increase in elevation. Even without glaciers, much of the interior ranges from 1000-1300 meters above sea level, comparable to the South African Plateau; which now supports the world’s largest subtropical highlands, similar climatically to the highlands in Ethiopia. Much of the North-Eastern side of the highlands drains into the Lambert graben, a permian-aged rift, which now forms a bay. Rivers coming down from the highlands introduce an immense amount of water into the bay, making the majority of the bay range from fresh to brackish, and with the sediment supplied by the mountains making this bay rather shallow. During Glacial maximums, this bay transforms into a low-lying plain, the sediment of which now makes the seabed ample territory for seagrass meadows. Further into the highlands, we find Lake Vostok, now relieved of its burden of ice. Without the depression from the ice above, the coasts of lake Vostok sit at about 1000 meters above sea level and are surrounded by subtropical forests. The lake’s depths nearly extend back down to sea level, supporting hydrothermal vents like those in Lake Baikal, with the only indication that something is different being the new flow of detritus from above. 

To the West we find a desert encompassing almost all of Marie Byrd Land and the Southern portion of the Palmer Peninsula. Sediment derived from the Marie Byrd land volcanic field, dispersed by the winds, colors vast swaths of the desert red. A few of the shield volcanoes in the Marie Byrd Land volcanic province rise high enough to capture some moisture, creating small oases of highland grasslands and in rare cases cloud forests. The Northern tropical forests of the Palmer peninsula are uniquely isolated from the mainland by Ronne bay to the East and the West Antarctic desert to the south, meaning any fauna here would likely be endemic to it. In the Ross Bay, the Transantarctic mountains cast a sizable rain shadow to the west, helping to form a narrow desert on the leeward side. In Ross bay, we also find a small archipelago of desert islands, with the largest being Penwell Island, a remnant of which exists in our Antarctica as Penwell Bank. To the South we reach the boundary between the tropics and subtropics. Near Antarctica’s new southernmost point we find the mouth of the Wilke’s river: the longest river on the Antarctic continent and which terminates with a wave-dominated delta. It’s also here that we find the largest permanent glacier on the continent, limited only to the highest points of the Victory Mountains.

Even without the circumpolar Antarctic current, Antarctica remains an extremely isolated landmass. No land bridges have connected it to any other continent since the Eocene, though South America (Now north of North America) remains just within reach. Ocean currents in the Drake Passage travel primarily from East to west, meaning that rafting events are unlikely to take settlers from South America to Australia, but could take settlers the other way around. It’s possible that South America could receive a regular influx of marsupials and other fauna from Antarctica over the course of millions of years. 

Resources Used:

Bedmap3: https://data.bas.ac.uk/full-record.php?id=GB/NERC/BAS/PDC/01615 

Reconstructions of Antarctic topography since the Eocene–Oligocene boundary: https://doi.org/10.1016/j.palaeo.2019.109346 

Total isostatic response to the complete unloading of the Greenland and Antarctic Ice Sheets: https://www.nature.com/articles/s41598-022-15440-y

This video showcases my Blender model of the planet that the Scud aliens call home, the fourth and final world I've mapped out for @jayrockin's "Runaway to the Stars" project. A *lot* of maps were created in service of this final render, and also in service of presenting the special qualities of this planet. I intend to show you as many of these as I can under the cut, and also in subsequent posts focusing on some of the more interstitial, ancillary maps and figures that played a part in producing the primary maps you'll see in this main post.

Before I show the first maps I made for this project, what you see below are the satellite-style maps for the Equinoxes and Solstices, in order of (Northern) Spring, Summer, Fall, and Winter, the latter serving as the texture for the Blender object you saw in the video.

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With that matter covered, our next focus is this project's foundation: Geology. While I didn't spin as elaborate a tectonic history for this planet as I did for the Ayrum commission, I did work out as much detail as I could for the more recent geological activity, to set the stage for the elevation data - including a narrower focus on the coastal shallows that host the Scud populations.

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Once I could move on to climate, my first step was finding this planet's relative Insolation, which I managed thanks to @reversedumbrella's code and coaching. With an obliquity of only 16 degrees, this planet's yearly maximum Insolation levels stick close to the equator, compared to pole-to-pole oscillation we see on Earth

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Having a rough sense of where heat would concentrate seasonally and how the landmasses would deflect water in light of the planet's retrograde spin, I was able to set down the bi-annual ocean currents (Northern Summer above and Northern Winter below), then the monthly water temperatures pushed around by said currents, and finally -after factoring in many other considerations- the monthly land temperatures as well (combined in the second gif)

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Next came the seasonal air pressure maps and subsequent wind patterns (my first time creating those from scratch), which later factored into the precipitation maps. The incredible temperatures at the largest continent's interior make a desert of most of it, and the other interiors are fairly dry too, but all that heat on the equatorial ocean generates a *lot* of evaporation which ends up coming down elsewhere.

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With temperatures and precipitation mapped out for each month, I was able to find how the accumulation and melt of ice and snow played out, too. Given such a hot equator it's surprising to see freezing temperatures hold out in some places, but low obliquity and high elevation shield what areas they can, it seems.

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All this monthly data was then painstakingly combined and compared and plugged into equations to produce maps of discrete climate zones, using both the Köppen (left) and Trewartha (right) classification systems. The higher latitudes see some overlap with Earth's conditions, but the Tropics...

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I never really finished the map I wanted to make with my own loosely customized classification system, but I *did* get as far as this breakdown of the areas that sometimes surpass 56.7 degrees Celsius, Earth's record for highest surface temperature ever directly measured. And as you can see, that earthly record is broken by a *significant* fraction of this planet's surface, and far exceeded by the equatorial continent's deep interior

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The final phase of this project dealt with creating satellite maps of this planet's surface (which you saw at the top of this post), which started with a map of dry and submerged substrate, then a density map of the vegetation that sits atop it, then the colors of that vegetation under annual average conditions (demonstrating how they would appear in-person, rather than the area's appearance from orbit), and finally plant colors under seasonal conditions (same conceit as previous). In concert with the seasonal ice and snow maps, it was the four maps in the last sequence which were overlaid on the Substrate map, using the plant density map as raster masks, to produce the final Satellite-Style maps.

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This planet's sophonts being a marine species, it was then worth focusing on the conditions underwater, which included monthly seafloor temperatures (first gif), annual discharge of sediment from rivers (magenta in the 2nd gif), and seasonal upwelling of nutrients from deeper water (blue in the 2nd gif).

The creation of all my maps seen in this post was possible thanks to Photopea, which has been my go-to for several years now. The resolution kinda got crunched when I uploaded these here, so when I share them on Reddit later I'll add those links under this. These have also already been posted on Twitter, which you can see here if you like. Thanks for scrolling all the way down here!

I almost forgot to post the Retrograde Australia map here!

Retrograde Africa (Africa on a backwards rotating Earth)

Retrograde North America (North America on a backwards rotating Earth):

I think this is my favorite retrograde Earth map I’ve made thus far, I’m hoping to work on Earth piece by piece until I have a full map.

Retrograde South America

This is my attempt to emulate a satellite map of South America on a backward spinning Earth, I based this on the climate maps made by Molotovsnowman and AncalagonTheBlack42: https://www.deviantart.com/molotovjack/art/Retrograde-Earth-V5-Final-Version-985503973

Which themselves were based on this study and this map from the Worldbuilding Pasta Blog

https://esd.copernicus.org/articles/9/1191/2018/

https://worldbuildingpasta.blogspot.com/2023/06/climate-explorations-day-length.html

Adelie, a tilted Antarctica

Tilted Africa

What if the Western Interior Seaway survived to the modern day?

Polar Africa

What if Australia was as it was during the Miocene?

Modern Messinian salinity crisis