G'Day All
As others have noted it is not always so easy. However that said, in the simplest situation gold and any heavy material will shed down slope, no matter which way a reef is dipping. Even in very flat ground there will always be a slope where gold will shed to. Now this is considering that nothing structural or geomorphic has happened to the area of the reef since it has begun to shed. If there has been some uplift or a creek or river has been captured be another river system what was a slope containing a shed will be abandoned and there will be a new shed direction. All goldfields have many dead ends as it were, the reef shed has been isolated and leads to nothing. More often than not that is because the reef has been eroded away or at least that part of the reef that was shedding gold has been eroded and no more gold is coming down. In all cases the best approach is to loam the area on a grid. Take a C horizon sample (that is where the top soil meets the broken rock), mark the spot with tape and a number and when you have collected as many samples as you can carry go and pan them off. Always have or make an accurate map of the area where you record the sample location, number and after panning the number of grains of gold and every creek and hill slopes. If you get some colour then redo that slope and catchment on a closer infill grid. This is exactly how modern explorers still work except we assay ever sample rather than pan them. Although I know a a few now major mines that were missed in assaying and discovered later by panning.
Araluen