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Thread: My Mountains Have Fallen and They Can't Get Up

  1. #1

    Help My Mountains Have Fallen and They Can't Get Up

    If anyone with knowledge of plate tectonics, vulcanism, and mountain placement can take a look at my work I could really use some feedback. It's a basic map I threw together before I get into terrain, because I can't work out climates until I am sure about my mountains.

    I am trying to create (or recreate) a fantasy world I have been working on for quite some time. I redrew my map and as I was working on the climate and currents, etc., I became skeptical that my mountain ranges were feasible. I have included a map below with the basic mountain structure. I was trying to justify the mountain ranges by reverse engineering the tectonics.

    I am not certain if any of it is workable. There are a few mountain ranges that I need to be where they are, but I am more concerned with constructing a world that is believable. The brown ranges are the result of tectonic pressure and the orange ranges are the result of vulcanism. I can play with the overall shapes of the ranges. These are not set in stone, no pun intended.

    Some information you might need to decipher my gobbledy-goop:

    A-E represent the tectonic plates I am proposing.

    A1 and A2 are either two separate plates or a single plate. I am leaning towards the latter. I don't believe a plate like A2 could even exist, but I might be wrong.

    The area marked 1, yellow, is where plates A and D are puling apart. Or to be more accurate A is moving NW.

    Plates C and E have separated from the "Pangea" of A, B, and D. I don't know if this is possible. [NOTE: The fault line for plate D should be to the west of the mountain range on the left and in the water. I didn't realize my mistake until it was too late.]

    I also have a question regarding glaciers, since they affect mountain ranges. There was a glacier moving south in the white area marked 2. How far south can it travel? Can a glacier reached the 30th parallel? [Now you know why I included latitudes.]

    I apologize if this is confusing. Any feedback regarding the tectonics, mountain placement, and that damnable glacier would be greatly appreciated.

    Click image for larger version. 

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  2. #2
    Guild Expert Gracious Donor Hai-Etlik's Avatar
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    My knowledge of geophysics isn't as good as my knowledge of Geodetics, so I can't give you as much help as with the projection stuff. Of course, you may consider that a good thing Still, this is all just to the best of my knowledge, and I may make some mistakes.

    You don't generally get long skinny plates, particularly not with a constricted portion in the middle. Both the continental part of a plate, and plates as a whole, tend to be compact shapes because bits that stick out tend to snap off.

    Coastlines generally follow the continental margin fairly closely, but you can have a few deviations to produce "continental" seas (Knowing where your continental margins are would be a big help, continental seas are often great fishing grounds like the Grand Banks). Volcanic arcs are generally produced by subduction of an oceanic plate, so they don't occur far inland and of on a continent, are often mixed with accretion type mountains like the Cascade Volcanoes in the North American Cordillera. The other kind of volcanic arc is produced by a "hot spot" under a moving plate (such as Hawaii) Either way, the volcanoes won't form a dense wall so much as a line of dots.

    If you want to place natural barriers, you might consider deserts, barren shield, and other things besides mountains. Mixing your barriers gives you a lot more flexibility. Just a shift in the the local climate or biome can make an effective barrier by simply being different rather than difficult. Even just a river can work, or a lake or inland sea. You also have a lot more flexibility with older mountains than with young ones. The Urals for instance are deep within Eurasia, but are comparatively flat and smooth compared to younger mountains. The Appalachians are another example of a very old range, though they are in a more conventional location.

    Islands tend to be hilly or mountainous submerged continent, or oceanic volcanoes. Oceanic volcanoes may be the aforementioned subduction zones (in this case one oceanic plate subducting under another, as with the Aleutian Islands), or Hotspots (Again, Hawaii), Triple Junctions where three plates meet often have particularly large or numerous islands, particularly if the plates are converging. Iceland combines a midocean rift with a hotspot to similar effect.

  3. #3
    Guild Novice Hawksguard's Avatar
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    What happens with your tectonic plates and the resulting mountain building action is going to depend on a couple factors, most importantly the direction of drift (which in your example, you've only listed A as moving NW, although you do mention that A and D are pulling apart, so I'm assuming D is moving SE.) The other big factor with plate boundaries is whether you are dealing with continental or oceanic crust. Generally plate boundaries fall into one of the following categories:

    Rifting Zones, where two plates are moving apart. Magma comes to the surface as "new" land is formed creating mountainous areas. Best examples of this are the mid-Atlantic ridge (longest mountain range on Earth) and the Rift Valley system of eastern Africa.

    Sliding Plates, where two plates are moving past each other. You'll get a lot of earthquakes here but not necessarily a lot of mountain building. However, the stress caused by the strike-slip action can have any number of effects on the plates involved, and you can feasibly get isolated areas of volcanism and mountain formation.

    Subduction Zones, where two plates ram into each other head on. Again, generally continental crust is going to get thrust upward as the oceanic crust subducts beneath it. As the subducting plate dives into the mantle, the high water content of the oceanic plate causes magma to form at the mantle-crust border. This superheated magma rises, leading to volcanism and mountain building at the surface. This type of mountain building is exemplified in the Pacific Ring of Fire, as well as the Alps and Himalayas. Another type of mountain building associated with this action takes place on continental plates as it "crumples" and uplifts when it goes head to head with a neighboring plate. The Rockies of North America are an example of this action.

    Of course, not all mountain ranges need necessarily be at active plate boundaries, even if you are striving for realism. As Hai-Etlik mentioned, you can have hot spots creating volcanic island chains in oceanic plates or supervolcano ranges in continental plates, such as Yellowstone. Some mountain ranges, such as the ancient Appalachians, were created by subduction of tectonic plates that have long disappeared into the mantle. (The modern Appalachians were created through uplift, much like the Rockies.)

    So basically I'd keep playing around with your plates, labeling them with different directions, until you get the right combination of mountain-building action. When creating my world I started with the plate boundaries, continental shields and direction of drift and then sketched out the resulting land masses. But there is no reason why you can't do the same thing in reverse.

    Your moving glacier does present a bit of a problem. While my expertise on glaciers isn't as thorough as my knowledge of plate tectonics, I will try to offer some observations. While glaciers have the ability to change morphology of mountain valleys, the affect is going to be pretty localized (the longest glacier in the Alps is only about 20 km long). If what you are really talking about here is the expansion of an ice sheet, then that, I suppose, could possibly reach as far south as the 30th parallel, but bear in mind that that's going to be accompanied by major climactic repercussions (and I thought MY world was cold). IIRC, the D&D Forgotten Realms world of Abeir-Toril had a huge "glacier" running amok through the center of it, but I believe that was a magically driven phenomena. *Correction: it was a desert running amok, not a glacier, although parts of it did have snow on it. My bad.
    Last edited by Hawksguard; 07-03-2011 at 12:32 AM. Reason: Edited for clarity and correction. Line breaks are good!

  4. #4

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    Quote Originally Posted by Hai-Etlik View Post
    You don't generally get long skinny plates, particularly not with a constricted portion in the middle. Both the continental part of a plate, and plates as a whole, tend to be compact shapes because bits that stick out tend to snap off.

    Coastlines generally follow the continental margin fairly closely, but you can have a few deviations to produce "continental" seas (Knowing where your continental margins are would be a big help, continental seas are often great fishing grounds like the Grand Banks).
    I though as much. I am redrawing the plates to be smaller and will combine A2 and C to a degree. When you say "continental seas" do mean when a tectonic plate that contains both land and a significant portion of an ocean?

    I am going to have to work on the plates involved with the major continent first. Many of the islands you see have not been dealt with, and they are supposed to be volcanic in origin (as you might have guessed). I will consider what you and Hawksguard have said and repost a new map tomorrow. I just got home and have to be back at work in less than 7 hours. Keeping the major plates in place but breaking them down into smaller components might be the best alternative.

    In regards to the barriers you mentioned. The area south of the mountains on the northern reaches of D is an expansive savannah and large portion that resembles the Kalahari desert. it's already a formidable barrier. I am not so concerned with how impassable the mountains are just as long as they create a rain shadow.

    EDIT: I forgot to thank you for your help. Thanks.
    Last edited by Porklet; 07-03-2011 at 01:22 AM.
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  5. #5

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    Quote Originally Posted by Hawksguard View Post
    Of course, not all mountain ranges need necessarily be at active plate boundaries, even if you are striving for realism. As Hai-Etlik mentioned, you can have hot spots creating volcanic island chains in oceanic plates or supervolcano ranges in continental plates, such as Yellowstone. Some mountain ranges, such as the ancient Appalachians, were created by subduction of tectonic plates that have long disappeared into the mantle. (The modern Appalachians were created through uplift, much like the Rockies.)

    So basically I'd keep playing around with your plates, labeling them with different directions, until you get the right combination of mountain-building action. When creating my world I started with the plate boundaries, continental shields and direction of drift and then sketched out the resulting land masses. But there is no reason why you can't do the same thing in reverse.
    Thanks in advance for your help. I get what your saying, but I just need to clarify a few terms:

    What are plate boundaries (I am assuming the edges of the plates, but I want to be certain)?
    What are continental shields?
    Direction of drift seems to be self explanatory and would tell me what type of activity I would have where the plates met.

    As I posted above to Hai-Etlik. I am moving towards breaking down the plates into smaller ones. This would allow for some of the vulcanism in the southern oceans that inevitably needs to take place and still allow for some actvity with mainland. I will work on it tomorrow and repost. As I posted I have to go back to work. Time for some Z's.
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  6. #6
    Guild Expert Gracious Donor Hai-Etlik's Avatar
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    Quote Originally Posted by Porklet View Post
    I though as much. I am redrawing the plates to be smaller and will combine A2 and C to a degree. When you say "continental seas" do mean when a tectonic plate that contains both land and a significant portion of an ocean?
    There are two kinds of crust that make up the plates. The thick but relatively light continental plate, and the thinner but much denser oceanic plate. The oceanic plate is the stuff that fills in the gaps when plates spread apart. Some plates are all oceanic, while others are continental, with bits of oceanic plate hanging off the edges.

    Now, all oceanic plate is covered with water except where really tall mountains stick up out of it. Continental plate is mostly above water, but around the edges it drops off a bit and is covered with water. This frill of water covered continent is called a continental shelf. Sometimes a larger area, possibly reaching far inland, is flooded, and that's a continental sea.

    At Oceanic-Continental convergent boundaries (where they are coming together) the oceanic plate "subducts" underneath and the ocean floor gets scraped up along the front edge of the continent. There isn't really much of a shelf in this case. The west coast of North America between southern BC and northern California (the Cascadia Subduction Zone) is a clear example of this. It has multiple parallel chains of mountains, frequent earthquakes, occasional MASSIVE ones, and volcanoes mixed in with the mountains.

    At Oceanic-Oceanic convergent boundaries, you get similar subduction, but instead of mountains, you get a deep trench, and then a chain of volcanoes behind that which may reach up to form islands. Earthquakes are the same as for subduction under a continent: frequent, and occasionally huge.

    Continental-Continental boundaries result in both being forced up into HUGE mountains. Without the subduction, you don't get the volcanoes or the really big earthquakes, though you still get the smaller quakes.

    Then there are the crazy complicated parts like the Mediterranean basin or the west edge of the Pacific.

  7. #7

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    Quote Originally Posted by Hawksguard View Post
    What happens with your tectonic plates and the resulting mountain building action is going to depend on a couple factors, most importantly the direction of drift (which in your example, you've only listed A as moving NW, although you do mention that A and D are pulling apart, so I'm assuming D is moving SE.) The other big factor with plate boundaries is whether you are dealing with continental or oceanic crust. Generally plate boundaries fall into one of the following categories:

    Rifting Zones, where two plates are moving apart. Magma comes to the surface as "new" land is formed creating mountainous areas. Best examples of this are the mid-Atlantic ridge (longest mountain range on Earth) and the Rift Valley system of eastern Africa.

    Sliding Plates, where two plates are moving past each other. You'll get a lot of earthquakes here but not necessarily a lot of mountain building. However, the stress caused by the strike-slip action can have any number of effects on the plates involved, and you can feasibly get isolated areas of volcanism and mountain formation.

    Subduction Zones, where two plates ram into each other head on. Again, generally continental crust is going to get thrust upward as the oceanic crust subducts beneath it. As the subducting plate dives into the mantle, the high water content of the oceanic plate causes magma to form at the mantle-crust border. This superheated magma rises, leading to volcanism and mountain building at the surface. This type of mountain building is exemplified in the Pacific Ring of Fire, as well as the Alps and Himalayas. Another type of mountain building associated with this action takes place on continental plates as it "crumples" and uplifts when it goes head to head with a neighboring plate. The Rockies of North America are an example of this action.

    Of course, not all mountain ranges need necessarily be at active plate boundaries, even if you are striving for realism. As Hai-Etlik mentioned, you can have hot spots creating volcanic island chains in oceanic plates or supervolcano ranges in continental plates, such as Yellowstone. Some mountain ranges, such as the ancient Appalachians, were created by subduction of tectonic plates that have long disappeared into the mantle. (The modern Appalachians were created through uplift, much like the Rockies.)

    So basically I'd keep playing around with your plates, labeling them with different directions, until you get the right combination of mountain-building action. When creating my world I started with the plate boundaries, continental shields and direction of drift and then sketched out the resulting land masses. But there is no reason why you can't do the same thing in reverse.

    Your moving glacier does present a bit of a problem. While my expertise on glaciers isn't as thorough as my knowledge of plate tectonics, I will try to offer some observations. While glaciers have the ability to change morphology of mountain valleys, the affect is going to be pretty localized (the longest glacier in the Alps is only about 20 km long). If what you are really talking about here is the expansion of an ice sheet, then that, I suppose, could possibly reach as far south as the 30th parallel, but bear in mind that that's going to be accompanied by major climactic repercussions (and I thought MY world was cold). IIRC, the D&D Forgotten Realms world of Abeir-Toril had a huge "glacier" running amok through the center of it, but I believe that was a magically driven phenomena. *Correction: it was a desert running amok, not a glacier, although parts of it did have snow on it. My bad.

    I have revamped the make-up of the world, and I have included a new map with plates and drift. The drift is not exact as I used my air current arrows as a brush so I don't have one that points SE. It will show, however, basic movement towards/away adjacent plates.

    Mountains: Light Brown represents new mountain formations that are still growing, Brown represents middle-aged mountain ranges, and the Dark Brown ranges are ancient. The red circles represent Hot Spots. I am not sure if I have way too many. There might be some areas where more volcanic activity might occur, and I am certain that the convergence of plates B, C, and H might have more upheaval. If you could point out areas where quakes or volcanoes would be prevalent feel free to point it out. If you have any other ideas please share them.

    Damn the glacier, and full speed ahead!

    I had noted your world map already. I believe it came up as a random gallery on the homepage just a few days ago. Although, I might have run across it looking at the work of others here. It looks very natural to me, and I like the feel of it.

    Thanks again.Click image for larger version. 

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  8. #8

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    Quote Originally Posted by Hai-Etlik View Post
    Islands tend to be hilly or mountainous submerged continent, or oceanic volcanoes. Oceanic volcanoes may be the aforementioned subduction zones (in this case one oceanic plate subducting under another, as with the Aleutian Islands), or Hotspots (Again, Hawaii), Triple Junctions where three plates meet often have particularly large or numerous islands, particularly if the plates are converging. Iceland combines a midocean rift with a hotspot to similar effect.
    Going back to what you said about Hotspots, I have included a new map in the above post. I have noted Hot Spots in several locations. I do have quite a bit of volcanic activity along plate edges. Is there every a situation where a particular plate is more vulnerable to have Hot Spots (such as plate I in the SW)? I could break it up into smaller plates, but it would be very difficult without producing some plates that simply couldn't exist. Any ideas?
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  9. #9
    Guild Novice Hawksguard's Avatar
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    Quote Originally Posted by Porklet View Post
    What are plate boundaries (I am assuming the edges of the plates, but I want to be certain)?
    What are continental shields?
    The question about plate boundaries I'm pretty sure has been answered, but just to reiterate, they are indeed the edges of the plates, whether or not they are actually "active". Continental shields are large areas of continental crust that are known for their geological stability, and are usually located far from plate boundaries. Created during the Precambrian, they represent the oldest rocks on the Earth's surface. Some examples of shields are northeastern Canada & Greenland, Western Australia, the Amazon Basin, and the Baltic area.

    Thanks for the compliments on my own world-in-progress. I take a lot of time and effort and study to make sure I'm getting my science down correctly and make sure there are no glaring holes that would "suspend disbelief", as it were.

    In regard to your question about hotspots, bear in mind that hotspots are not a function of tectonic action -- it is tectonic action that makes them easily identifiable. The technical term for a hotspot is "mantle plume", and as the name would suggest, the mechanism that creates them has its origin deep in the mantle of the earth. Mantle plumes DON'T move...the tectonic plate above it does. As a result, you get a new volcano to form over the plume head when tectonic action moves the plate far enough. Since mantle plumes are not caused by tectonic forces, they can occur anywhere and in fact are most easily identifiable when they happen in the middle of a plate, like Hawai'i or Yellowstone, where there is no logical reason for geologic activity to be taking place there. If you have a planet that is geologically active, it would make sense for them to be "popping up" all over.

    Another thing I would also suggest is don't overthink it. It is easy to get caught up in being scientifically accurate, but there comes a point when you become bombarded by too much science and it all becomes meaningless drivel. Looking at your most recent map, I would observe that there is no immediately apparently reason why there should be mountains between B & C, or F & I, or H & L, since these pairings illustrate neighboring plates moving in the same direction. However, the main force(s) causing plate tectonics is by no means constant. Plate W may have moved at rate X in direction Y for Z million years, but any one of those variables could change at anytime.

    The bottom line is once you've got your scientifically plausible geosphere, all pretty and polished with a high glossy sheen, don't be afraid to totally obliterate it if the story you are trying to tell through your map says 'It Must Be So."

  10. #10

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    Quote Originally Posted by Hawksguard View Post
    The question about plate boundaries I'm pretty sure has been answered, but just to reiterate, they are indeed the edges of the plates, whether or not they are actually "active". Continental shields are large areas of continental crust that are known for their geological stability, and are usually located far from plate boundaries. Created during the Precambrian, they represent the oldest rocks on the Earth's surface. Some examples of shields are northeastern Canada & Greenland, Western Australia, the Amazon Basin, and the Baltic area.

    Thanks for the compliments on my own world-in-progress. I take a lot of time and effort and study to make sure I'm getting my science down correctly and make sure there are no glaring holes that would "suspend disbelief", as it were.

    In regard to your question about hotspots, bear in mind that hotspots are not a function of tectonic action -- it is tectonic action that makes them easily identifiable. The technical term for a hotspot is "mantle plume", and as the name would suggest, the mechanism that creates them has its origin deep in the mantle of the earth. Mantle plumes DON'T move...the tectonic plate above it does. As a result, you get a new volcano to form over the plume head when tectonic action moves the plate far enough. Since mantle plumes are not caused by tectonic forces, they can occur anywhere and in fact are most easily identifiable when they happen in the middle of a plate, like Hawai'i or Yellowstone, where there is no logical reason for geologic activity to be taking place there. If you have a planet that is geologically active, it would make sense for them to be "popping up" all over.

    Another thing I would also suggest is don't overthink it. It is easy to get caught up in being scientifically accurate, but there comes a point when you become bombarded by too much science and it all becomes meaningless drivel. Looking at your most recent map, I would observe that there is no immediately apparently reason why there should be mountains between B & C, or F & I, or H & L, since these pairings illustrate neighboring plates moving in the same direction. However, the main force(s) causing plate tectonics is by no means constant. Plate W may have moved at rate X in direction Y for Z million years, but any one of those variables could change at anytime.

    The bottom line is once you've got your scientifically plausible geosphere, all pretty and polished with a high glossy sheen, don't be afraid to totally obliterate it if the story you are trying to tell through your map says 'It Must Be So."
    Although I have dreaded taking this step you have made it much easier for me, and I thank you. I do not want to overthink it. However, I have changed the direction of B to work against C since I do want the largest mountains in the world to be in that area. That being said I am almost satisfied with it, but I do have a couple of questions if you don't mind.


    1. Are plates moving away from each other more likely to have volcanic activity? Thinking this was the case I did not place Hot Spots along plates G & I, G & J, and H & K.
    2. You refer to F & I and H & L, but I don't have any mountains there. Could you mean the mountains along the sea between D, G, and H? Those are remnants of prior collisions. The mountains in the interior are mega-ancient (to coin a term) and are not affected by current tectonic conditions.

    I follow you in regards to creating a believable natural world. The history of this world is that is was discovered by the "gods" not created by them. The gods then created men. The natural world was untouched by man or god until this discovery. They can toy with the forces of nature, but they can't break them. I can't truly screw with the nature of things until there is a nature of things.Click image for larger version. 

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