I’m not sure what that video said, exactly, but both water and dirt move because they are both affected by tidal forces.
Tide is caused when an object, like Earth, is large enough to experience a difference in the effects of orbital gravity from one end to the other. The center of gravity of an object does not experience tidal forces.
Since most of the Earth’s surface is water, and the water is on top of the dirt, the water should be affected more by tidal forces than the dirt underneath it.
The video may have been talking about how the dirt affected by tidal forces also pushes the water, causing a compounding effect or something.
marcos@lemmy.world 19 hours ago
Some of the first mechanical calculators were created to predict tides (~3 centuries ago), because they are a really complex thing that the popular explanations completely paper over and pretend it’s simply the water keeping pace with the Moon.
MotoAsh@piefed.social 18 hours ago
It’s shown like that because the water is trying to do that, to anthropomorphise it. Though of course that’s not what the water does everywhere because fluid dynamics get pretty nuts when there’s a ton of land in the way.
MotoAsh@piefed.social 12 hours ago
To expand on the idea, even weather effects the level of the tides rather significantly… For a clear example, look at hurricanes. They can approach double digits in feet of storm swell if they’re severe enough.