Reconstructing Eorzea's geological history.

[Skies]

[*]Thanalan Caves
Thanalan is riddled by a network of tunnels that appear to have been naturally formed. In some locations, such as West Thanalan, these tunnels have opened up and connected with the surface. The presence of water suggests they are formed by subterranean water flows. (can someone find me a real-world comparison?)
The mineral composition suggests rocks of felsic origin (mostly granites) that have undergone metamorphism through burial before erosion.
The specific combination with amber (fossilised tree sap) suggests sedimentary deposits at least where this mineral is found (cave systems are easier formed in sandstones of eroded pegmatites rather than the original rock). In a previous age, parts of Thanalan would have had a very lush vegetation (wider historical coverage of the Twelveswood?).

I am unforunately no moose foutain of knowledge, however. I do certainly have in my memory at least on NPC that mentions that Thanalan was once a more lush and green place. In fact if memory serves me it was a gridanian who said it, attributing the desertification to the fact that the denizens of Thanalan would effectively hunt their Elementals.

Now you mentioned continental drift. I'm not trying to suggest that the uplift of the Coerthas mountains happened in the space of a few thousand years (the earthquakes would be civilisation-breaking). I'm suggesting that it's been going on since "creation".

Part in bold. The earth-elemental umbral era, anyone?