Just thought I’d share this example of how the virgin wash layer looks around Lisle which the old timers were chasing. The layers are quite clearly defined, on the bottom you have the light coloured decomposed granite which is very soft and easy to dig almost like chalky sand. Right on top of that you can see the thin stained red gravel layer and this is where the richest gold lies. It’s very hard packed almost cemented together.
Sometimes you can expose these layers in the bottom of old leads and faces or excavator test holes but in my experience they always contain pretty poor gold which is probably why it’s still there. One day i’ll find a good one…