Does the Sea of Silt have currents, waves, and tides? One the one hand, surface winds and the gravitational pulls of the moons would cause disturbances in silt, but because it’s much denser than water, I think these effects would be very muted. There likely wouldn’t be any deep currents because the silt becomes hard-packed not too far under the surface and there is no thermohaline circulation. That said, maybe there’s some volcanic gases (or magic creating a similar effect) keeping the whole thing fluidized?
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The tides of silt are said to move in and out (exposing and covering ruins), but on a longer timescale than water - like, weeks, not hours - which is probably just from the wind.
I agree with the hard-packing meaning no deep currents.
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I’ve always imagined the athasian silt
as less dense than water as it sits on top of the sea of silt with water underneath.
Tides would definitely be impacted by the moons. I would say Guthay would have the biggest impact on tides. High tides tend to occur when the sun, moon, and planet are all lined up. Which means on full moons and new moons.
If you care for using any timing between phases of the moon just take half between full moons for the time between high tides. and then half way between that time period (quarter/ three-quarter moons) for low tide.
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I always imagined that there are numerous portals to the Plane of Silt in the Silt Sea, and that is what gives it its water-like behavior. The moons would affect it, but to a lesser degree.
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Warer settles to the bottom of the silt, but there’s not like free water down there, generally speaking.
I introduced the Asherati as a subspecies of humans who live in the deep silt and were survivors of the Cleansing Wars who were cut off from home. The top of the silt is “puffy” and easily moves in the wind causing the waves that are seen by the silt sailors. The deeper the silt the more packed it gets. The Asherati are able to build small cities that never see the light of day in the deep silt with crops using incredibly long tendrils to reach the sun and deep roots that grow through the deep silt and into the water trapped under the deepest compressed silt. All the silt that Athasians’ are familiar with are a byproduct of defiling magic interacting with the life shaped brown tide.
The term silt is misleading since silt eventually sinks in water, but it was similar to something those in the green age knew (but didn’t understand what was really happening) and the name stuck.
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Silt and the Silt skimmers have always given me problems, but the posts above have given me pause and for what it is worth, here are some thoughts.
If there is water under silt, i.e. silt is lighter than water, how do Silt Skimmers work? If they run on silt by compressing it (or by running on packed silt below the surface), then that compressed silt would / could ‘sink’ - though you could assume the water is so far below that the compression isn’t significant.
I’ve gone for the silt replacing the water as a result of the devastation caused by the (non canon) conflict between Raajit and the Champions. (In effect, the water was ‘defiled’ to become silt). That allows the compression to work, which prevents the skimmers from sinking. If the silt is lighter than water, the skimmers can then move as if in water, so that allows them to move around well enough. The silt cannot be as ‘liquid’ as water, otherwise the compression of the wheels wouldn’t happen. (You would need to watch the weigh on your skimmer, compared to the diameter of your wheels, and the width of the treads. There’s a physics article waiting there, but not from me… 
) I assume that the compression from the skimmers doesn’t last long, though I quite like the idea of a harder layer under the surface. (Though that gives me an issue with silt burrowing creatures, so I’ll stick with it all being fluid).
The silt is light, so wind will affect it as water - worse in some respects creating Silt Storms as it whips it up. It’s not a huge stretch to have the silt, as a magical / defiled creation to ‘remember’ its watery origins, and be affected by the Moons, giving tides. Since currents are largely caused by rotation and the effects of temperature differentials, no reason too why those shouldn’t be there, though as I’ve stated that the silt isn’t as ‘liquid’ as the water, they would not be as strong.
On ‘my’ Athas the devastation is centered on the Tablelands, so only the relatively shallow oceans there became silt. Further away, water still flows.
Not that any other rationalization for a silt sea can’t work, ofc, but just some thoughts!
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From my understanding the water isn’t just sitting pure under the silt, but that there is thick muddy water under the silt, as the silt gets mixed into the water, it doesn’t just sit on the top., that’s why so see places where there are mudflats coming up out of the silt, there is some sort of spring nearby or something putting more water into the silt so that it creates mud all the way up to the surface instead of under 10–20-50 or more feet of dry dust.
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That works, and certainly helps with mudflats etc!. Water underneath also explains what happens to any rain that falls on the silt seas. Thanks!
I still have the problem of how a muddy mix is lighter than ‘pure’ water. So perhaps the mix is a pure emulsion (i.e the silt particles are incapable of absorbing water), caused by water sinking slowly through the silt and eventually settling underneath from rain, whereas a mudflat, with a constant feed of water would maintain the emulsion at the surface through continually churning it up.
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