Geology of Roshar (aka rocks)

[I Am Witless]

Does Brandon ever specific what type of rock it is that makes up the bedrock layer for Roshar? It doesn't seem to be mentioned anywhere, and the type of stone dictates how a formation erodes. And where does the crem come from? It seems to be a clay-like sediment that is eroded off of the bedrock layer, but I can't think of any common earth stones that easily erode into particles of that size. Volcanic rock, both extrusive and intrusive, would erode into larger chunks, so maybe the bedrock layer of Roshar is sedimentary of some sort? 

[Walin]

Maybe it's all just uncasted pottery?

But in all seriousness, I think that it is one of two things: Regular sedimentary stuff that becomes mud in the humidity of highstorms, or rock that generally breaks into bigger chunks that get broken apart in the high winds of highstorms, eventually dissolving into drops of mud after successive crashes with other flying boulders and stuff.

[king of nowhere]

if this was a real, nonmagical planet, I'd say the contninent must be made of volcanic rocks, as all rocks are either volcanic or sedimentary (or metamorphic, but in that case they derive from either volcanic or sedimentary anyway) and highstorms pretty much exclude large accumulation of sediments. but this is not a real planet.

wob also says roshar doesn't have much geological activity, so no volcanic eruptions and growing oceanic ridges that are the main way in which rocks are made on heart. investiture is certainly acting heavily there, as all that crem just does not get lifted naturally wherever the origin of storms is. in general, weknow rosjar has been engineered heavily by shards: it has three satellites in very unlikely orbits that are unstable over astronomical timelines, it has a continent with mountains without having any mechanism for orogenesy, and the whoole continent is made according to a mathematical equation. So, since it was a shard who made roshar, it made roshar of whatever it wanted. we just cannot speculate accoridng to science when science clearly does not apply.

[+Extesian]

Given Roshar (continent) is a slice of the Julia Set I have a notion that Adonalsium took a cooling planet and applied some kind of force to it, matching a Julia Set equation, as it was cooling. I'm no geologist, so whatever rock is formed when magma cools, that's what I'm guessing.

as for crem, I'll just leave you with this.

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QUESTION

Is crem spren poop? Or at least… not literally, but something like it?

BRANDON SANDERSON

Yes, it’s more like Shard poop. (Somewhat unsure sounding?

 

[Pagerunner]

Crem falls with the highstorms; I thought that was made clear from the books. They collect the rainwater in cisterns, and let the crem settle out before drinking it. Except for the Weeping, where water falls without crem, which is why they can use to to clean the sand in the training grounds in the Kholin warcamp. There must be organic components to the crem - stormwater is better for their crops than freshwater, we learn in one of Kaladin's flashbacks. That's almost certainly due to the crem suspended in it.

The flora and fauna of Roshar, being reminiscent of coral and crustaceans, has caused some of us to propose that the continent was raised from the ocean floor with an already thriving undersea ecosystem, and then populated with Parshendi and humans at a later date. That would mean the stone would be the same kind that you find on the bottom of the ocean floor; sedimentary, I believe, but it's been a long time since I've played the Magic School Bus game where you learn about rocks.

[+Extesian]

8 minutes ago, Pagerunner said:

Crem falls with the highstorms; I thought that was made clear from the books. They collect the rainwater in cisterns, and let the crem settle out before drinking it. Except for the Weeping, where water falls without crem, which is why they can use to to clean the sand in the training grounds in the Kholin warcamp. There must be organic components to the crem - stormwater is better for their crops than freshwater, we learn in one of Kaladin's flashbacks. That's almost certainly due to the crem suspended in it.

The flora and fauna of Roshar, being reminiscent of coral and crustaceans, has caused some of us to propose that the continent was raised from the ocean floor with an already thriving undersea ecosystem, and then populated with Parshendi and humans at a later date. That would mean the stone would be the same kind that you find on the bottom of the ocean floor; sedimentary, I believe, but it's been a long time since I've played the Magic School Bus game where you learn about rocks.

Yeah Brandon gives a good description here

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QUESTION

I get the impression after reading Stormlight 1 and 2 that a lot of what you would consider to be flora is actually something like coral in the ocean which is actually an animal. So is there actually any flora on Roshar outside out of Shinovar…

BRANDON SANDERSON

Almost all the things you see as flora are actual flora. Like, rockbuds are flora, trees are flora, shalebark is not, and some of the things like that - haspers are not, and some of these things are more - are animal life, are fauna. But grass is actually a flora, and trees. One of the big adaptations they’ve had to make is that they have to use crem, so a lot of the tree that you’ll find on Roshar, they will be using crem that falls - they use this to create shells, they use this to create bark, they use this in a LOT of different ways, the minerals there are very important because they’re not getting from the soil what plants on our soil get from soil, a lot of them do. All of your minerals and things have to come from the crem. Which the farmers already knew.

 

[king of nowhere]

a couple scientific nitpicks:

- just because plants use it, crem does not need to be organic. plants get carbon from air with photosynthesis, and hydrogen and oxygen from water, and they rely on soil to get all the other elements, most abundantly nitrogen and phosphorous. but they do not need organic molecules; inorganic nitrates and phosphates are perfectly fine.

- rock in the ocean floor is volcanic. magma seeps out from oceanic ridges, solidifies and makes new oceanic floor, pushing out the existing floor. the mechanism is regular enough that you can estimate the age of an oceanic floor solely based on how far it is from the oceanic ridge. I studied this stuff in my native language, so some of my english terminology may be inaccurate.

[Mistform]

I would use the term Igneous not volcanic, volcanic rocks are igneous but they are also porous due to the gas from a volcanic eruption. If crem is from eroded bedrock it would not be clay immediately because clay requires chemical breakdown unlike sand or silt.

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inorganic nitrates and phosphates are perfectly fine.

To nitpick your nitpick, inorganic nitrogen usually requires nitrogen fixation to be available to plants.

How crem is recycled is an interesting question as garbage left out can be blown and left in the next town by a highstorm, so it can't take a rock and break it down gradually. Rivers erode their bottom during floods/high water events, then deposit sediment as the water level goes down again. So I guess crem recycling would work by the highstorm eroding then depositing. I feel like some of the crem must be ocean floor sediment to get enough sediment volume, however much of the nutrients in the ocean come from terrestrial sources, which presents a problem here.