Tectonic Plates
Tectonic plates are enormous slabs of the Earth’s lithosphere, which is divided into several major and minor plates. These plates float atop the semi-fluid asthenosphere beneath them, constantly moving and interacting with one another. These interactions between plates over geological timescales can create supercontinents or tear landmasses apart, all the while giving rise to terrain features such as mountain ranges, oceanic trenches, and volcanoes. Fictional tectonic plates can help worldbuilders create ‘realistic’ landmasses and terrain for their fictional planets as it can be the interaction between these plates that govern where on a world or fictional map these elements exist.
| Synonyms: plates |
| Example Mythonyms: the Ingru Plate |
Designing Fictional Tectonic Plates
Overview
To design a fictional world map using tectonic plates, start by sketching out the layout of the plates. Consider the number and size of the plates, as well as their boundaries. Earth has seven or eight major tectonic plates (depending on how they are defined) and dozens of minor tectonic plates.
Plate boundaries are the borders where tectonic plates meet and interact. It is at these boundary locations where most of the geological activity occurs. There are three primary types of plate boundaries:
| Convergent Boundaries: Plates collide, resulting in subduction zones where one plate slides beneath another. This process can form mountain ranges (as the upper plate is forced up) and oceanic trenches (where the lower plate is forced down) Convergent boundaries are responsible for both the Marianna Trench and the Himalayan Mountains. |
| Divergent Boundaries: Plates move away from each other, creating basins and valleys. They are also responsible for mid-oceanic ridges where the asthenosphere mantel has moved up through the gap between the plates and solidified. |
| Transform Boundaries: Plates slide past each other horizontally, causing earthquakes and the formation of faults. |
Mapping fictional tectonic plates and their interactions (are they colliding with one another or separating), can provide insight into what terrain features may appear and where on a planet they may be found.
Other planetary landscapes are also created by tectonic plate activity, such as the Valles Marineris rift valley on Mars.
