[r9etb]

I meant "soft" in the geological sense. Sandstone is a heck of lot harder.

Well, I know that.... ;-)

And basalt is harder than sandstone -- and yet Dry Falls was apparently formed in a very short time frame. With enough water and abrasives, you can do a lot of damage....

[BigBobber]

Sandstone is a generic term. Some sandstone is harder than basalt, some is as soft as soil.