Reconstructing Eorzea's geological history.

[Catapult]

Some of you may already know this, others get to find out now. By trade, I may work in economics, but my education is in geology. And it rocks!

At various points, I've made some small attempts to piece together what we know from Eorzea's physical make-up, but I've never managed to form a properly cohesive picture. (This wasn't helped much by the original release's repetitive landscapes.) I figured it might soon be time to make a more concerted effort and lay the foundations for some deeper analysis of the v2.0 landscape.

I figured we could start with some basic fact-gathering, so I'm going to start making a list of what we know. If you can think of something not on my lost or possibly provide some juicy gems of added contextual information, feel free to contribute.


Places of Geological interest:

• Mt. O'Ghomoro
  An active (?) volcano at the heart of Vylbrand. Mined by the Kobolds. Surrounding associated rocks appear rich in iron, cobalt and sulphur (brimstone). Bears spinels and Turquoises, indicating the volcano's lava flows are mafic (mostly basalt) and contain notable amounts of magnesium, aluminium-based feldspars and copper.
  
• The White Cliffs of Vylbrand
  Most of Vylbrand's shore is made of high cliff-faces in front of a white sandy beach. Possible comparisons include the White Cliffs of Dover, which are made of chalk and flint, or the Twelve Apostles, which are made of limestone. Both formed underwater and this geology suggests the coastal areas of Vylbrand would need to have been submerged at some point for an extended period of time (sixth umbral era?)
  
• 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?).
  
• The Whispering Gorge, Jadeite Flood and Black Tea Brook
  This appears to be one of Eorzea's major rivers, springing in the Northern Black Shroud, flowing through Gridania and possibly feeding Silvertear Lake before cascading down Silvertear Falls into the ocean. I'm not sure how much to draw in terms of conclusions at this point.
  The Coerthas River and other mountain lakes around Coerthas probably also feed into Silvertear Lake. ((Edit: River theories need some work. Deferring to ARR.))
  
• South Shroud Kimberlites
  It is worth noting that Gridania's geology is probably highly complicated. This is highlighted by the presence of Garnet and Peridot in the same rock bodies around Camp Tranquil, which is only possible if the rock has been buried below 100km depth. The most common way for these to get to the surface is through a kimberlite, which is the stuff you find diamonds in.
  
• Silvertear Lake
  While the Silvertear falls are a significant landmark, it only exists because of the sheer rock face holding back Silvertear Lake. The presence of an island at the very centre is also interesting, suggesting the formation is a crater lake such as a volcanic crater or meteor impact site.
  (I'm thinking perhaps an association with the Tomb of Xandes/Crystal Tower descending underground, but other ideas are very welcome.)
  
• The Sea of Clouds and Abalathia's Spine
  The mountains of Coerthas steadily climb to a peak near the gates of judgement, where they then decend into a plateau commonly filled with clouds. Further to the north is another mountain range called Alabathia's Spine. My guess is that the Sea of Clouds corresponds to the Tibetian Plateau. This would suggest that the Coerthas mountain range represents a continental plate boundary where Mor Dhona is being steadily thrust beneath Coerthas and uplifting the Alabathian range. (Other ideas are welcome.)
  
• Ishgard's Spire
  The pinacle upon which Ishgard is built is reached via a combination of natural and man-made bridges. I'm still thinking about this one.

Known Natural Disasters:

• Seventh Umbral Fall of Dalamud
  'Nuf Said.
  
• The Fall of the Keeper
  Disrupted the Aethertic flow and caused crystalisation (fossilisation?) of much of the vegetation. Interesting for the future geological record.
  
• Sixth Umbral Flood
  Submersion of large parts of Eorzea. If we assume it lasted for a reasonable amount of time, we could align this event to the formation of the cliffs of Vylbrand, although I'm sceptical they could be that young and so quickly formed. More likely, the current cliff height is a representation of the height of the waters during the Sixth Umbral Era.
  
• Fifth Umbral Ice Age
  Glaciers would have probably dominated Coerthas, carving out the large rifts over which the iconic bridges are built. The Sea of Clouds may have been filled with ice.

Over to you, folks. Let's see some geomancy!

[Myranda]

Nice write-up, tip o' the craton to ya. I've nothing much to add right at the moment, unless we're soon handed out acid droppers and streak plates for ARR field work.

But I can have some musings with no substantiation!

First I wonder how much continental drift truly goes on in Hydaelyn. If we take the history of the astral and umbral eras with each era lasting a few thousand years, that doesn't leave a lot of time for drift to occur. Unless it's ridiculously fast (in which case we'd be seeing rapid active changes in the present), there is a time before the eras when Hydaelyn existed in a pre-historic state and the eras simply mark the beginning of written history, or my assumption about eras being roughly equal in time span is false (i.e. compare Pre-Cambrian to Cambrian, and sorry if I'm mixing eras/eons/periods it's been a while).

It's also clear that the aether and elemental affinities play a role in Hydaelyn geology/geography as well, something that obviously has no real world equivalent. Mor Dhona was lush forest not but 10 years ago but has since become a wasteland due only to the aetherial balance going out of whack... we can presume the region hasn't moved appreciably in latitude, etc or else Eorzean cartographers would be in quite a frustrated tizzy (either that or Ul'dahn merchants would wet their pants in excitement at the profit potential). So some things just won't quite match up to a pure sciencin'!

[Catapult]

It's also clear that the aether and elemental affinities play a role in Hydaelyn geology/geography as well.

Something a lot of fantasy writers do when creating their worlds is begin with the laws of our own world and then add magic. This not only creates a sense of familiarity to stop the world being too alien, but also helps emphasise that which is different.
Options for Eorzea include rapid geological progression during Umbral Eras, while Astral Eras return to "normal" (what we are familiar with).

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".

The scientist in me is also very wary of taking the myth of creation surrounding the first umbral era too seriously - creation myths have a habit of mis-representing the truth.


(Your terms are on the money: the pre-cambrian period represents about seven eighths of geological time on earth, and simultaneously all of "day two" in the bible's first creation myth.)

[Myranda]

I'd be inclined to go with the long history and slow (read: normal) drift myself, with the eras only referring to recorded history. I'm on board with you that the creation myth isn't literal creation of Hydaelyn, but only the citizens current idea of it given their stage in technological advancement (barely any know what a planet is after all).

Also, if Silvertear really is an impact basin, maybe we ought to search the strata for rare elements (a la KT boundary iridium). If it is an impact though, either the local rock is highly resistant to erosion, it's a relatively recent impact, or the aether concentration is interfering with the erosion, preserving it.

I'm also surprised the Coerthas River isn't marked on the world/regional map. But I'd guess it doesn't flow into Silvertear. Nothing seems to flow into or out of it actually with the White Maiden skirting around the NW mountains, but it's also not a highly detailed map...

In fact it looks like after the Coerthas joins with Swiftrun at the Riversmeet confluence (see Coerthas map), they fall off into the Sea of Clouds at Greytail Falls and presumably flow north to the Farreach. Of course, that's based on 1.x maps and ARR may have changes in store for us, especially considering the massive topology changes Bahamut hath wrought.

Also based on the world/region map, I'd guess the Coerthas mountains' uplift is a result of Sharlayan/Dravania/Farreach plowing into the rest of Aldenard. I don't think Mor Dhona is being subducted, seems more continental on continental buckling which creates the tallest mountains anyways. However, if Vylbrand is part of the Dravanian plate, the seafloor of the Strait of Melthor could be closing up and that portion of subduction is driving O'Ghomoro?

The area between Thanalan and the Shroud is also marked by smaller mountains, hinting that Thanalan joined Aldenard at an earlier time in history and has since eroded down somewhat (which could support Thanalan having been an equatorial rainforest previously as you stipulated, since Eorzea is now roughly centered at 30°N).

[Mjollnir]

It's a shame the botany doesn't make much sense. Part of me wishes that either:
a) The trees/shrubs look like the same plant you get from logging/harvesting, or
b) They'd just used new, exciting Eorzean names for plants (ie like Rolanberry) instead of "Oak", "Ash", etc.

Anyway, in relevance to the OP, do you think that the geology has been designed to make much sense, considering this? Or is it just going to be that higher tier rock and metal is going to be in the higher level zones?

[Xeia]

This topic is awesome, if a little confusing for me. >_>

• 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?).

Now, I admittedly no very little about geology, so I could be way off on this... I know you said the mineral composition makes it unlikely that it's sandstone, but it's possible the items recovered in mining can't be trusted, as Mjollnir pointed out with botany. As far as a real world example of that, I'm sure the sandstone caverns of Arizona (and surrounding areas) came to mind. They also often are sort of... "open-roofed" caverns, like the areas in Western Thanalan on the way to the ferry.

If you want something less... sandy... then I do have another suggestion but it comes with a heavy disclaimer of I probably have no idea what I'm talking about. Upstate New York's Howe Caverns. They're made of limestone, though I have no idea if that's ...felsic, but I'm guessing probably not, since it isn't granite. Now... I know Howe Caverns don't open up to the surface like you mentioned, but they do have flat ceilings with "pillars" reaching up to them. It looks a lot like the geography of Western Thanalan would if you just slapped a large flat rock on top of it. Conversely... I thought maybe Howe Cavern would look more like Thanalan if that ceiling got thin enough and collapsed, only leaving thin strips where the "support beams" are to hold it up -- like those floating paths we have in game. Though the color doesn't match.

Sorry for the long paragraph, especially if I'm talking nonsense >_<

Options for Eorzea include rapid geological progression during Umbral Eras, while Astral Eras return to "normal" (what we are familiar with).

If we take everything at face value, then this idea is supported pretty well by the game, I think. We've played the game during an astral era and everything was static (or, to be lore friendly, changing slowly enough that there's no observable differences day-to-day), while the Shroud of v1 looks drastically different from the Shroud in the alpha/beta gameplay trailers, and all that difference has occurred just over five in-game years. Concept art shows other dramatic changes besides what we've seen there.

Of course... a lot of these changes were actually caused by real world circumstances, so it's unclear how much of the 1.0 geography has actually changed as far as the Eorzeans are aware and how much we're supposed to consider retconned into its new 2.0 form.

[Catapult]

Also, if Silvertear really is an impact basin, maybe we ought to search the strata for rare elements (a la KT boundary iridium). If it is an impact though, either the local rock is highly resistant to erosion, it's a relatively recent impact, or the aether concentration is interfering with the erosion, preserving it.

Impact crater, volcanic maar, or something else are our options. I'm going to keep my money on the "subduction of the Crystal Tower" idea for now, but maintain an open mind till we possibly get some mineral samples from the area. (mining in Mor Dhona - can I haz?)

world/regional map

I take that world map around about as seriously as this one:

Creating localised maps is one thing, creating a cohesive world picture is another and Earth didn't get it properly right until we launched a rocket up and started taking pictures. It also reminds me of the following classroom discussion that was still typical a few decades ago.

Whippersnapper Student: Africa and South America... did they once fit together?
University Professor: Don't be silly! The earth doesn't move.

But you got me on one thing: I'm going to have to re-think my river theory, as the relative positioning seems to show nothing feeding Silvertear Falls, which disturbs me slightly.

Do you think that the geology has been designed to make much sense, considering this? Or is it just going to be that higher tier rock and metal is going to be in the higher level zones?

Bit of column A, bit of column B. Knowing SE, I doubt they would throw basic geological theory to the four winds, but I'm not sure if they've realised they've set the South Shroud up for Diamond deposits either.

I know you said the mineral composition makes it unlikely that it's sandstone, but it's possible the items recovered in mining can't be trusted, as Mjollnir pointed out with botany.

Fair point, but there is only one person who can tell us for sure. But we can use what evidence we have to narrow down to a model of best fit, and things are at least loosely fitting at this point.

As far as a real world example of that, I'm sure the sandstone caverns of Arizona (and surrounding areas) came to mind. They also often are sort of... "open-roofed" caverns, like the areas in Western Thanalan on the way to the ferry.

If you want something less... sandy... then I do have another suggestion but it comes with a heavy disclaimer of I probably have no idea what I'm talking about. Upstate New York's Howe Caverns. They're made of limestone, though I have no idea if that's ...felsic, but I'm guessing probably not, since it isn't granite.

Limestone is calcium based, where as felsic and mafic are your more traditional rock. Felsic rocks are known for being whiter and with a decent amount of quartz in them. Mafic rocks are far more black.

But I like that Arizona Caves example. Not perfect, but a good type to think about.

It's unclear how much of the 1.0 geography has actually changed as far as the Eorzeans are aware and how much we're supposed to consider retconned into its new 2.0 form.

Yeah... >_<

[Catapult]

Also based on the world/region map, I'd guess the Coerthas mountains' uplift is a result of Sharlayan/Dravania/Farreach plowing into the rest of Aldenard. I don't think Mor Dhona is being subducted, seems more continental on continental buckling which creates the tallest mountains anyways. However, if Vylbrand is part of the Dravanian plate, the seafloor of the Strait of Melthor could be closing up and that portion of subduction is driving O'Ghomoro?

The area between Thanalan and the Shroud is also marked by smaller mountains, hinting that Thanalan joined Aldenard at an earlier time in history and has since eroded down somewhat (which could support Thanalan having been an equatorial rainforest previously as you stipulated, since Eorzea is now roughly centered at 30°N).

Even in continental buckling, there is a plate that is technically subducting. It just gets crumpled up in the process. In the Himilayas, India is dominated by China (sorry, politics) in a continuation of what was once ocean subducting beneath the Tibetian coastline.


Such a setup would put any potential volcanos on the Sharlayan side of the boundary rather than the Vylbrand side.
The local geology also suggests that O'ghomoro is more of a hot-spot-style volcano.

Of course, there can always be something more complex going on. ^_^

[Myranda]

Ah good points, I wasn't thinking quite completely about some of the ramifications of direction of the subduction.

Thinking more about Silvertear... the whole lake seems to be surrounded by small mountains, so even if there is no outlet or inlet, could it be filled just as a giant rain or groundwater reservoir? It also seems that the situation in 1.x was that the Falls had pretty much dried up. They were labeled off on the west side of the map but no (surface) waterway connected them to the Lake. Compare this to the intro movie showing their state before the Battle of Silvertear Skies where it was practically Victoria Falls in scale.

And it might be possible the central island where the Keeper of the Lake is is a direct consequence of the Keeper' formation. I watched through the intro movie again and it's hard to tell whether the Agrius is touching down on land or if its pure water, but its conceivable the crash itself and resulting aetherial explosion uplifted some of the surrounding land.

[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?