Okay, NOW I'm starting to get what you're going with this.
![Time :time](https://elementscommunity.org/forum/Smileys/solosmileys/../../../images/Misc/time18x18.png)
- 'River' should technically be called Oasis, unless you're referring to things such as the Nile River and whatnot.
![Gravity :gravity](https://elementscommunity.org/forum/Smileys/solosmileys/../../../images/Misc/gravity18x18.png)
- 'Craters' should be here, as meteors are both huge objects that are defined by their mass and relation to gravity itself (making an impact on the world of elements). 'Craters' can also work for
![Aether :aether](https://elementscommunity.org/forum/Smileys/solosmileys/../../../images/Misc/aether18x18.png)
too, because they're known to contain resources from beyond this realm...
![Earth :earth](https://elementscommunity.org/forum/Smileys/solosmileys/../../../images/Misc/earth18x18.png)
- Valley/Canyons are also good choices for the third one, and imply the idea of crevices within the earth that lead to caves - Valleys/Canyons could be used for the other elements
"updrafts" upon these areas, you have the ability to reach the overworld. (the land of air). ...
![Air :air](https://elementscommunity.org/forum/Smileys/solosmileys/../../../images/Misc/air18x18.png)
and/or
![Fire :fire](https://elementscommunity.org/forum/Smileys/solosmileys/../../../images/Misc/fire18x18.png)
- You can probably add 'Geysers' (small springs noted for their explosive nature, releasing steam/heated water into the air)
...on another note, are we adding more terrains, or are we trying to use the ones that you have listed now? ^^;