Mud Flood Theory is a rabbit hole. Filled with mud.
Instead of doing the work to excavate it myself, I dumped it off onto Panda and Morgan from the podcast The Dumb and the Restless -- which covers topics of Pacific Northwest weirdness in a road-trip format.
(I found them when they mentioned tree octopuses on Twitter. If you mention tree octopuses on Twitter, I will find you.)
In case you're unaware of Mud Flood Theory, this is the elevator-pitch part of the email I sent them suggesting it as a topic:
The gist: Sometime in the last few hundred years, an unknown event buried buildings across the globe in a layer of mud, anywhere from a few feet to completely covering them, and there has been a conspiracy to keep this secret from the public through historical revisionism and gas lighting.
Mud Flood researchers also speculate the event wiped out -- possibly intentionally -- all evidence of an ancient, technologically advanced civilization centered in Great Tartary, which had cities all over the world, upon the ruins of which our "modern" cities were built -- a theory called the "Grand Tartarian Civilization Reset".
The only physical evidence that any of this happened is basement windows in old buildings that are inexplicably below street level.
They've just posted their episode about it: "It's In The Mud", so give them a listen!
These are the mentioned video links I sent them (the Olympia one was what made me think of them, since they're based around there):