I remember that rock. Two newbies borrowed Matt Matson's dredge and found 13 ounces in 2000. The next year two pros hit the same spot and picked up 65 ounces before the rock moved and scared them out of their hole. I believe I was told the hole was 30 feet deep.
The rock I was talking about was on the Umpqua River at Rivers West RV Park. That's where they held their first Dredge Earth First Rally in 2000. That rock in Johns' post looks exactly like it.