Inspired by this post by Deborah Christian on World Builder’s Academy and Random’s post on Reddit, I’ve decided to look into possibilities of doing this on a spherical surface so as to avoid the distortions inherent in applying the motions on a flat surface onto a putative spherical world.
I’m going to use two methods. One will be an attempt to temporarily tape “continents” onto a handy globe and move them about; occasionally taping some together or cutting them apart. The second broad method will use gplates to roughly simulate what I’m doing with the globe on the computer.
Both methods will follow the same rough rules. For each landmass(or piece of paper), I will roll an eight-sided die. The number rolled will determine the direction of movement, 1 being due north, 2 being north-east and so on around the compass rose in a clockwise direction. A six-sided die will also be rolled, 1 or 2 determining that the “landmass” rotates to clockwise, 3 or 4 denoting a counter-clockwise rotation, 5 no rotation and 6 will have a
special effect. The movements and rotations will be fairly small and by eye. In the event a six is rolled on the six-sided die, I will chose a point randomly on the landmass and I will use that as the center of a rifting event to split the mass into three new “continents”, each of which will henceforth move independently. In order to clarify any possible confusion, I have created illustrations of this process.
The next rule is that when two landmasses collide they will be attached together and henceforth move together unless divided by another rifting event. Some note should be made of the rough date of collisions and rifting events. These can be considered mountain-building events and their relative age could be used to control the application of erosion. Older mountain ranges would be lower and more eroded.
These rules are kind of primitive and they only really deal with shapes of continental margins and mountains created by intercontinental convergences, but they are a decent first try at creating a believable landscape. A more sophisticated model would do more to model mountain building due to subduction at oceanic boundaries and other effects, but for now this will have to do.
Today, I’ll start with the paper-on-globe method. Hands-on physical reality may make what we’re trying to do a bit clearer. First we need a globe. I’ll be using an actual globe of the Earth that I picked
up at Goodwill for three bucks. My original intention had been to sand the globe down and prepare it for the Chris Wayan Planetocopia treatment, replacing its surface with my own created world. Unfortunately, I’ve never had the heart to sand off its lovely surface, so it’s sat in the living room doing nothing but being decorative for the last year. Because I don’t want to damage the existing surface, I have to be somewhat careful how I attach things to the globe. I could avoid some of those worries by using a more prosaic ball, but the only ball I had available was somewhat
larger than my globe. Not much larger, but even on the globe I’m using Africa is about the size of an 8-1/2 x 11-inch sheet of paper and Asia is quite inconveniently large. Sticking the “continents on would also be a bit of a challenge. Although my trusty duck tape would have probably done the job most nicely, it would also have completely trashed the globe. I suspect Post-It notes could have easily been twisted to the purpose, but, strangely, I don’t seem to have any of those on hand at the moment.
I didn’t put too much effort into drawing precise shapes, which turned
outnot to be too much of an issue because my skills with a pair of scissors were barely up to the task of following the shapes of the blobs I drew. Perhaps next time I’ll have my grade school kids do the cutting. And drawing…
Even if the shapes had been intricately drawn and precisely cut with an exacto knife and a skilled hand, much of that would have been lost
in trying to force the flat sheets onto the curved surface. I wasn’t surprised that the larger cut-outs(approaching “Africa”-sized) were somewhat problematic, but even pieces smaller than “Australia” were still somewhat involved to force onto the surface. Had I been willing to use a stronger adhesive things likely would have been easier, but I suspect the required deformation would have still limited the detail attainable.
Some of the tasks involved in playing the Plate Tectonics Game were
unexpectedly involved. Each movement required the cut-out to be pulled up and laboriously re-stuck to the globe. Taping continents together after collisions wasn’t too difficult, but cutting them apart proved rather involved. Also the more rigid masking tape I used made it difficult to get the continents to deform to the surface. It seemed like they would have been pre-deformed, but not so much… I tried making cuts in situ, but that proved unnecessarily
difficult. Taking continents off the surface and trying to re-adhere them to the same location and orientation was error-prone at best.
Even though I ultimately did a pretty half-assed job with the paper-and globe method of tectonic drift simulation, it was still time-consuming and more than a little bit frustrating. The shapes were ultimately pretty vague. Whatever the results, they would have been
difficult to record with any precision. Possibly, I could see carefully measuring the latlong positions of vertices on the perimeter and using that either to start an equirectangular map on graph paper or enter into your favorite cad program. Might be useful for an all-by-hand-approach, but if your going to use a cad program anyway…
As a proof of concept, doing this with paper and globe was of interest, but I wouldn’t want to do it regularly. This turned out to be an all-day project. The results were not impressive enough for an all-day project. I give this one thumbs-down.
I’m already working on the gplates and qgis version of this little simulation/game. Hopefully it will be quicker…
Thank you for reading,