Over millions of years, the Earth has gone through many changes. Sometimes, a river that is laden in gold will be thrust up and dry out. That is why you may find placer gold high up in an exposed rock bed with obvious water-warn rock. Sometimes the river changes courses, and new rivers cut across the old channels. No matter how things change, the fact remains that the gold came from a vein, which eventually became an outcrop. Knowing this, many modern-day prospectors are switching from working barren streams to hard rock, and hunting for those outcrops with could lead to a very valuable vein. Even if you do not work it yourself, you may have a good discovery which could mean another person or company will buy or lease your find!