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Joined: Mon Dec 26, 2011 12:53 am
Posts: 115
 Post subject: (Map) A new version of my old world map
PostPosted: Thu Feb 02, 2012 2:52 am 
I'm kind of a Mars freak... I love the red planet, so a lot of my world maps (even for fantasy games) have been based on various terraforming possibilities, or scenarios in which the (comparatively) warm wet period of the Noachian age never ended. Personally, I prefer the look of a "terraformed" mars, as that preserves the massive vertical shifts the planet is known for (Valles Marineris, Olympus Mons, etc). I've used altered versions of the maps from Kim Stanley Robinson's "Blue Mars" for a while, but I recently took some screenshots of the Google Mars map, and played around with them til I got something I liked.

Essentially, I took multiple screenshots and joined them into a mosaic that covers the whole planet (Mercator projection style). I then played around with the colorshifting in GIMP until I got the relief/elevation colors to look more "real-world", as the actual colors from Google Mars are designed more toward contrast than terrain. After that, I erased everything I wanted to cover in water, then paintcan-dropped a water-like texture on the background layer.

Now, for those purists out there... I did NOT follow either the datum or the -1 contour that is fairly popular. I was looking for interesting, not accurate. In a similar fashion, some craters that actually have solid rims now have breaks in their rims for water flow. The Hellas Basin in particular is much changed from what it would actually be if you just dumped a load of water in it.

The map is intended to represent a world that undergoes regular cataclysmic meteor showers (every few thousand years). For feature naming on this map, I have generally stuck to the classical albedo features or to the "official" names. I have my own names I use in my campaign, but I figure it'd be easier for someone to look up details if they knew what everyone else calls them.

World Map
World Map with equator marked
Note: The map links take you to a box.com download page. The actual download link is in the top right.

A few details

The lowest point on Mars is either Melas Chasma (near the equator, in Valles Marineris) or Hellas Planitia (southern hemisphere near the center). The highest point is the peak of Olympus Mons (left side of map, north of the equator).

I left out a distance scale intentionally. If you go with the actual size of Mars, the distance across the map at the equator is about 13,200 mi or 21,300 km. If you want an Earth-sized world, double it (that's close enough). Anything else, just make up what you like (though I wouldn't go much smaller than Mars itself).

Mars has two moons, Phobos and Deimos. Both are too small to have any serious effect on tides, and both move in a relatively low orbit. When viewed from the equator, Phobos appears about 1/3 the size of our moon, and crosses the sky from west to east in about 4.25 hours, rising again 11 hours later. Deimos rises in the east and sets in the west, but is visible for 2.7 days, rising again 5 days later. Neither moon is visible from the poles.

Yearly Weather Patterns
Mars has an elliptical orbit, which has an interesting effect on seasonal weather. At perihelion (closest point to the sun), the northern hemisphere is in winter, and the southern hemisphere is in summer. Aphelion is the northern summer and southern winter. Because of this, seasonal temperature differences in the north are typically mild, while those in the south are extreme (and exacerbated by the lack of water in the south).

Mars itself is extremely cold, though it is theoretically possible to thicken the atmosphere enough to bring average temperatures well above freezing (it is assumed this has been done). Even at sea level in the equatorial regions, average highs don't get much above 70F/21C. Southern winter lows are enough to kill a human with no shelter in a few hours.

The seasons on Mars are odd as well. One Mars year is about 687 days. Personally, I use the Darian Calendar, but I ignore the leap year & stick an extra day in the 27-day months. That adds up to 672 days, which is close enough for me, and easy to keep track of. Because of the elliptical orbit, some seasons are longer than others. The northern hemisphere spring (southern hemisphere autumn) lasts 7 months, while the northern hemisphere autumn (southern hemisphere spring) lasts 5 months. Northern summer/southern winter is 6 months, while northern winter/southern summer is 5 months (Note: this is simplified).

Wind Patterns
Much like Earth, Mars has tropical easterlies, prevailing westerlies, and polar easterlies. Because the patterns of land and water are so different from Earth, these winds can have some interesting weather effects.

The primary settled areas of the planet are around the equator, so wind in these area will most often be coming from an easterly direction (southeasterly if south of the equator, northeasterly if north of the equator). The plains north of the Tharsis Bulge and the northern edge of Arabia Terra (north and a little west of Hellas) are the only northern-hemisphere lands to be affected primarily by the prevailing westerlies.

The southern hemisphere is mainly highland desert, with craters acting as oases and the Hellas Sea acting as a replacement Mediterranean Sea. From the equator down to the northern third of the Hellas Sea, tropical easterlies are the predominant winds. From that point south to the ring-shaped crater lake southeast of Hellas, you get prevailing westerlies. From there south to the pole, you find polar easterlies.

One final wind "pattern" to keep in mind is katabatic wind. These winds are caused by high-density cold air being pulled down a slope by the force of gravity. When the air mass above these elevations gets cold and dense enough, it will rush down the slopes with the force of a hurricane (on Mars, this is literal. on Earth, not so much). The extreme elevation changes on the surface of Mars create favorable conditions for these winds, and they can form downslope of any major rise. The two most common regions for this are around the Tharsis Bulge and Elysium Mons, but they can happen in any steep canyon. Frequently, the tropical easterlies will push their way up onto the Tharsis Bulge, cooling as they rise in elevation, until they reach that critical tipping point where the wind speed is not enough to overcome the weight of the air. Then, the wind rushes back down the slope to the east, channeled straight into Valles Marineris.

The Northern Ocean & Major Currents
The Northern Ocean is situated over Vastitas Borealis, and has a VERY salty composition. It is theorized that Vastitas Borealis is actually a colossal crater that encompasses most of the northern hemisphere, which would explain its relatively low elevation and its comparative lack of major craters. That's not really important to a fantasy game, but it's kind of interesting.

The main current in the Northern Ocean occupies a straight band halfway between the southern edge of the polar cap and the northern edge of the plains above the Tharsis Bulge. It runs around the globe in a westerly direction with a very strong flow, making it difficult to sail or swim in. Most ships stay just to the south of the main current if they are traveling east (to take advantage of the prevailing westerlies). If traveling west, they tend to skirt the coastline to take advantage of the tropical easterly winds.

A clockwise subcurrent circles south along the shore by Olympus Mons, goes west between Elysium Mons and the mainland, then curves back north to rejoin the main current.

A second subcurrent follows a similar path to the west, dropping down into Chryse Gulf and then coming north to rejoin the main current.

A minor current inside Isidis Planitia (north of Hellas and west of Elysium) circles counterclockwise.

Other Bodies of Water
Valles Marineris, a split in the crust formed by either volcanic or tectonic activity, is more of a fjord than a river. The walls of the canyon are extremely steep, and there is some water flow toward Chryse Gulf and the Northern Sea.

The Arabia Sea runs along the southern edge of Arabia Planitia. It is (mostly) freshwater, and actually composed of several joined lakes rather than a single large sea. It is filled by drainage from the highlands to the south, and empties both through a river on the western end, and through absorption into swamps on its north edge.

The Hellas Sea (south center) has a mild counterclockwise rotation from Coriolis forces. Excess water drains northward into the Northern Ocean. The water composition is brackish

Argyre Planitia, south of Valles Marineris, is a fertile crater bottom partially filled by a freshwater lake that drains northward through Nirgal Vallis into the Arabia Sea, then into the Chryse Gulf.

Landforms Along the Equator
On the western edge of the map is a tall shield volcano called Olympus Mons, the largest mountain in the solar system (the peak is around 26km above sea level). At the base of Olympus, especially on the northern and western sides, are extremely fertile plains fed by volcanic ash. This is probably the easiest land to farm on the planet (once you get the ejecta out of the way).

The largest landform is the Tharsis Bulge, the yellow and brown area on the equator at the western edge of the map. This region is a high area that is somewhat barren, but not quite a desert. A barren, rocky land, this area is left alone by most people, though caravans do traverse the bulge to trade between the Marineris region and the fertile lands at the base of Olympus Mons. Because of the altitude, temperatures frequently drop well below freezing, and snowpack typically drains into Valles Marineris. The green areas to the west and north of the Tharsis Bulge are mostly coastal farmland & forests.

Northeast of the Tharsis Bulge is the drainage area for Kasei Vallis (the water-filled valley going north-south). This is a wild fertile region with densely-forested slopes.

The Valles Marineris region is a network of fertile canyons surrounded by rocky highland. Rugged folk live in nearly-vertical cliff towns on the fjord itself and make a living fishing from the deep waters of the trench, while the more sedentary farm in the outlying canyon bottoms. Valles Marineris is a frequent target for katabatic winds off the Tharsis Bulge.

Arabia Terra (the green area near the center of the map) is an extremely fertile area, with swamps along the Arabian Sea and beaches along the Northern Ocean. This region is the centerpoint of human civilization, which exists in a series of feudal states. Industries are based on fishing, farming, logging and hunting.

The island north of the equator on the eastern side of the map is Elysium. Primarily covered in forests and some farmland, it is high enough to escape most of the Northern Sea's bad weather. Unfortunately, the island chain just northeast of it is regularly battered by cyclonic storms forming just off the Tharsis Bulge, AND by katabatic winds coming down off Elysium itself.

Landforms in the Southern Hemisphere
The southern hemisphere is primarily dry, rocky highland desert. Crater bottoms are generally protected from the dry winds by their crater rims, and so can sometimes collect water from underground aquifers and serve as oases in the desert. Two major exceptions exist.

The Hellas Basin region is fairly brimming with life, and the fertile land around the sea is covered in dense forests, going to swamps and fens on the islands. The Sea within the basin in fed by aquifers in the surrounding crater rim which are in turn refilled during the harsh winter.

Argyre Planitia (south of Valles Marineris) is also fed by aquifers in the crater rim, but is much more subdued than Hellas. Argyre is filled with flat, fertile plains, very vulnerable to an aquifer outbreak (which is probably what filled Hellas in the first place).

Terra Cimmeria (yes, that's the actual name) is the highland desert region east of Hellas and southwest of the Tharsis Bulge. The low-lying areas of this region can sustain some hard-scrabble farming, but there is very little water to be found. Desert plants and animals predominate, and nomadic bands of humanoids make this a dangerous place to travel.

Terra Sirenia is east of Cimmeria and south of the Tharsis Bulge. It has many more crater oases than Cimmeria, so life here is not quite as hard.

Noachis is the region southeast of Argyre and southwest of Hellas. It is a blasted area, covered in overlapping impact craters and upheavals. This, combined with the almost complete lack of water, make it an extremely difficult region to traverse.

Polar Regions
The Northern Polar Ice Cap is similar to Antarctica. It is made primarily of water ice, and exists year-round with little change in shape or extent. The ice runs straight down into the Northern Sea, with no actual land to be seen. The cap itself is cut with wind-carved canyons and shaped by howling winds that blow primarily from the northeast. The water is choked with icebergs, and any sailor foolish enough to brave the Northern Sea's currents will have his ship smashed to bits in short order.

The Southern Polar Cap changes greatly with the seasons. In the summer, it recedes to a tiny mass of water ice in the far south. In the winter, it stretches out to cover the smooth yellowish land on the south edge of the map, and is composed primarily of frozen carbon dioxide, or dry ice. Travelers who manage to climb the southern ice cap in the winter are likely to be overcome by toxic CO2 fumes from the ice being melted by their body heat.

A Final Resource Link
If you like the idea of altering an existing planet, there are some interesting maps available on this page...
The World Dream Bank: Planetocopia

This artist goes through climates, possible evolutionary paths, all kinds of stuff.

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Joined: Wed Apr 15, 2009 10:33 am
Posts: 19
 Post subject: Re: (Map) A new version of my old world map
PostPosted: Wed Feb 08, 2012 11:24 am 
Wow! The World Dream Bank: Planetocopia website is an awsome resource. Thanks! :)

"The Dude abides."

Joined: Mon Dec 26, 2011 12:53 am
Posts: 115
 Post subject: Re: (Map) A new version of my old world map
PostPosted: Wed Feb 08, 2012 1:15 pm 
Drohem wrote:
Wow! The World Dream Bank: Planetocopia website is an awsome resource. Thanks! :)

Yeah, there's a lot of nifty ideas on there :)

Joined: Sat May 22, 2010 10:16 pm
Posts: 129
 Post subject: Re: (Map) A new version of my old world map
PostPosted: Wed Apr 25, 2012 3:38 pm 
Wow. Thanks for that.

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