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I'm building a new planet up from scratch, and wanted to get a sanity check on my plate tectonics and land masses. It doesn't have to be 100% realistic, but I'd like it to be plausible to someone who knows what they're looking at.

Description

  • Diagram shows two hemispheres of a globe.
  • Plate boundaries are outlined in grey, and labeled with letters (A-J), with arrows for their general movement direction.
  • Continents are outlined in green; other areas are assumed to be ocean (there are 4 major continents - AB, FJ, C, and HI.
  • Primary Mountain ranges are indicated in red.
  • Earthquake/volcanic activity regions are indicated in purple.
  • Islands/archipelagos are indicated in yellow.

Caveats

  • The planet is roughly earth-like in composition, age, and size.
  • The coastlines are not set yet, this is just the preliminary shape of the land masses.
  • I'm not set on any particular configuration, if there's a need to scrap elements of the sketch.

Desired Answer A good answer will suggest improvements or revisions to the sketch to make the planet more realistic, based on your knowledge of geology and plate tectonics. Also appreciated are recommendations that aren't necessary for this sketch, but could be implemented in future undertakings, or things to keep in mind going forward, i.e. how the coastlines would be affected by their formation.

Prior Research and Uncertainties The concept sketch is based on my understanding of geology, several blogs (particularly this WorldbuildingWorkshop post) and articles on worldbuilding via tectonics, as well as reading through the relevant forum posts on this site. I couldn't find any information on how Hadley cells work near the poles, so those plates' motion is where I'm least confident. Also I'm unsure what features would form when plates are moving roughly parallel, as in the D-F plate border.

proposed planet land diagram

First-time poster, thanks very much for your advice!

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    $\begingroup$ It may be worth adding mountain ranges that belong to extinct plate boundaries, the the Appalachians in the US. $\endgroup$
    – John
    Jul 16, 2020 at 13:41

2 Answers 2

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I notice a couple of important omissions from the article you cite.

1. Pangaea

You might want to consider whether there was a Pangaea on your world and, if so, how the continents originally fitted together. enter image description here http://www.glosgeotrust.org.uk/downloads/pangaea.jpg

Animation of the rifting of Pangaea https://en.wikipedia.org/wiki/Pangaea#/media/File:Pangea_animation_03.gif

Video of Pangaea https://vimeo.com/14258924

Pangaea (Wikipedia) https://en.wikipedia.org/wiki/Pangaea

Note that this will also determine something about the distribution of species in your world relative to evolution continuing after isolation. It will also tell you about similarity of geology (mineral deposits etc.) along the lines where the continents were originally joined.

2. Volcanic islands

Undersea volcanic 'islands' may eventually grow to appear above the surface. Sometimes this can happen in a matter of days! These can have a very steep coastline descending precipitously to the sea bed. Volcanic islands grow upwards from faults.

Dramatic volcanic eruption creates new island south of Tokyo - Truthloader Investigates https://www.youtube.com/watch?v=S0_ANqwuCzA&feature=emb_logo

3. Continental shelf

Continents however, spread apart from faults. Be aware of the phenomenon of continental shelves. When continents move apart they don't just break off vertically at the land. There is usually (relatively) shallow water around the edges, with a break to the deep water occurring further out. This has a big effect on shipping, tides, ocean currents (and therefore climate), undersea life, etc.

enter image description here https://en.wikipedia.org/wiki/Continental_shelf#/media/File:Southeastern_United_States_continental_shelf.jpg

In particular shipping is affected. Large ships can't get close inshore, whereas local fisher folk can get right up to the beach in their small rowing or paddle vessels. This makes for distribution centres and even cities to grow around large rivers where the channel is deep enough for large vessels. London is a prime example.

Useful references

The following website Written In Stone...seen through my lens has some great illustrations showing cross-sections of undersea and above sea coastlines. https://written-in-stone-seen-through-my-lens.blogspot.com/2011/10/champlain-thrust-fault-at-lone-rock.html

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  • $\begingroup$ to be fair during times of high progression (very high sea level) like the Jurassic the shoreline and continental plate boundary may be drastically different, and we don't know which we are looking at. $\endgroup$
    – John
    Jul 17, 2020 at 3:32
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On Earth the places where two plaques collide and form mountains are at high risk of big earthquake (see Andes and Japan), while on your map all the mountain regions existing in such area are not marked as seismic. Due to the high strain induced in the rocks, this is unrealistic.

I also find odd that the continent in E is delimited exactly at a diverging border. Those are usually deep under the ocean.

Additionally, Hadley cells are a meteorological phenomenon, they have nothing to do with geology

The Hadley cell, named after George Hadley, is a global scale tropical atmospheric circulation that features air rising near the Equator, flowing poleward at a height of 10 to 15 kilometers above the earth's surface, descending in the subtropics, and then returning equatorward near the surface.

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