[eartrumpet]

"Apparently, a wet spring lubricated across a cap rock. Then, a small spring on either side caused the bottom to slide out. He estimated 15 to 20 million yards of movement."

20 million cubic yards is a fairly respectable pile of dirt. So where is it? I don't see a nearby river choked with sediment carrying it away.

[Red Badger]

Maybe it sunk.................

[volunbeer]

The displaced dirt went into an underground void. There are all kinds of voids big and small in every shape imaginable underneath the Earth’s surface. We usually call them sinkholes.

That is the only thing that makes sense to me. Certainly very unique!

[Darksheare]

More likely it is still there.
It is possible that a block of earth slumped.
The second image, everything in center from the crack left possibly slumped left.
I’d love to see more images of the foot of the hill.

[ProtectOurFreedom]

I looked, too. Sure no signs of the material being washed out of the sides of the gash. Sure looks like a tensile failure to me. What forces pulled that hill apart?

Gotta be a wild Saturday night party in the underworld.