Within the last million years, erosion effects have gradually exposed the gold to the surface, and gold particles from shallow veins have been washed into rivers. It was possible to run across gold in the Keelung River, which is how it was discovered in the first place.
再造金九風華金瓜石地區的金礦形成後，又因地殼上升被抬高，在最近一百萬年間，遭各種侵蝕作用交逼，使得礦體逐漸露出地表，許多淺部礦體的黃金更被沖刷到河川之中，九份、金瓜石，甚至遠達八堵的基隆河，都可以發現砂金，這也是最初金礦被發現的原因。