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1 Answer 1

  • Always start with a chart of Earth's plates before you. We know they work! Use them as a guide. JBH, JBH

  • Tectonic plates always have low spots and high spots. Though not mandatory, the low spots are usually water basins or edge oceans and the high spots are often plateaus and mountains. JBH

  • Most oceans are on a tectonic plate. They are also the largest. I would recommend finding the coasts that look like they could find into a different coast on an adjacent continent. Martamo

  • Plates should never meet at a “t”. A “t” is a four-way meeting of tectonic plates. Martamo

  • Plates will move and rotate. When they move away from one another, they create rifts (e.g., the Great Rift Valley). When they collide they create mountains (e.g., the Himalayan Mountains) or island arcs.

  • Volcanoes (and associated with them hydrothermal springs) and earthquakes frequently happen along plate boundaries (e.g., islands and mountains). This is especially true when the plate is rotating rather than moving. JBH Also, sometimes volcanic activity can be caused by hot spots (so called intraplate volcanism) or even a combination of both (e.g. Iceland).

  • Plates (fault lines) rarely cross in the middle of landmasses. It isn't that they can't, it's that water erosion usually eats away at the sides of the land masses, leaving seas between the two land masses with a plate division along the sea. Thus, a plate bisecting a continent (incredibly rare) would have been two plates pushing together for a very long time, resulting in a substantial mountain range bisecting the continent. JBH, GaultDrakkor

  • Though hard to imagine, it is believed the U.S. Rocky Mountains (forming the U.S. Continental Divide) were caused by the shockwaves of two plates colliding. In other words, mountains don't form only because of two plates pushing against one another. Mountains (or, generically, "high spots") also form due to meteor strikes or, perceptually, from water erosion (e.g., draining Lake Bonneville) or wind erosion (U.S. southwestern bluffs) due to low-density rock being blown away from high-density rock. You can also have sink holes due to the type of rock (e.g., limestone). In short, you need to realize that you'll have high spots (mountains) and low spots (lakes...) in locations other than plate boundaries. JBH

  • Your average plate will have ocean encompassing a landmass. JBH

  • In the majority of cases, touching landmasses will touch lightly or with small stretches of land (e.g., an isthmus). Note that an isthmus can form due to soil buildup around the two plate boundaries having little or nothing to do with the plate boundaries. I.E., ocean currents deposit sediment that reinforces the currents' behavior until an isthmus forms. JBH

  • Polar caps help identify how much water is available. In a warm year there's less cap and more water, meaning greater separation between land masses. In a cold year there's more cap, less water, and more connectivity between the land masses. JBH

  • If your map is only showing coast lines, it doesn't show us topography, which is really what we need to identify plates. You can identify tectonic plates and derive mountains from them, or set your mountain ranges to identify plates. In the end, your goal is a topological map. JBH

  • Fault lines run parallel to ridge lines, not perpendicular to them. JBH

  • Fault lines frequently run parallel with a series of deep-water points rather than bisecting them. JBH

  • Islands frequently pop up along fault lines. JBH

  • A tectonic plate frequently encompasses a body of water and some coastline, or a large landmass with some coastline. Not both (Something is causing the subsidence of the ocean or "supersidence" of the land mass). As an example, if you look at the Earth's South American Plate, you'll see that the fault lines run along the major mountain range along South America's western coast, and the trench lines in the middle of the Atlantic Ocean. It encompasses all of South America — but not all of the Atlantic Ocean to the next continent. JBH

  • Boundaries should be mostly made of many joined roughly 120 degree 3 way junctions, right angle T, or large smooth arcs of subduction island arcs (Aleutian islands, Java), and if you have an island arc it should be on a subduction zone Image examples island arcs John

  • Tectonics plate are usually made of continental AND oceanic crust or just oceanic crust, because forming oceanic crust is part of how plates move, it is always present. Even the Arabian plate has small slivers of oceanic crust. John

  • Tectonics plate boundaries are defined by what kind of crust is interacting and how, there are 6 basic ways and it may be worth looking at them, in short any combination can form convergent boundaries, and give you drastically different geography based on which. Divergent boundaries are always the same on both sides (both oceanic or both continental), as well as transform boundaries) which are displaced relative to each other. [John]

  • 3
    $\begingroup$ I don’t believe that the bullet mentioning the Marianas trench is correct. Plates pulling apart form a series of ridges as new material rises from below. I believe the Marianas trench is in a subduction zone, where the pacific plate dives under an Asian plate. If I can confirm this later I will edit… $\endgroup$ Jun 27, 2023 at 14:26
  • $\begingroup$ @MichaelHall --- Were you able to confirm? $\endgroup$
    – elemtilas
    Oct 4, 2023 at 0:51
  • $\begingroup$ @elemtilas. I haven't had time to research, but very confident. Look up "Mid-Atlantic Ridge". $\endgroup$ Oct 4, 2023 at 2:56
  • $\begingroup$ plates should not meat at a t they should meet at 3 way junctions made of roughly 120 degree angles. 4-way junctions are very rare. Also yes the Marianas trench is a subduction zone, chasms form when continental crust separates not oceanic crust. $\endgroup$
    – John
    Oct 4, 2023 at 20:00
  • $\begingroup$ I wonder it is would be useful to have a few example fictional maps and point out what is wrong with them. In the attitude of picture is worth a thousand words $\endgroup$
    – John
    Apr 20 at 18:34

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