Great advice Bob. Just wish you didn't give it out Haha...
I have a spot like that called "road wash". Like you I drove over it many times. I saw a little trib one day and decided to check it out.
It ran right into the road. Well, I got a bunch of 1 grammers and smaller ones out of it. Even a couple on the hillside and benches.
The next time I went through the area the monsoons had blasted the road out and what was usually a foot or more of overburden was now bare craggy bedrock.
I detected the road and found a bunch of small nuggets! Even a sunbaker.
Quads/dirt bikes and side by sides come through the area a lot. They would look at us with bewilderment digging and raking and we would just say, Doing some county road maintenance is all 😁
Tom H.