This is the panning technique. You simply put gravel that has gold into the pan and add water. Then you shake it side to side and look to discover gold at the bottom of the pan.
This technique is called hydraulic mining. There is a pipe that shoots water against the side of a mountain and the mountain slowly sheds away while revealing gold.
This mining technique is called The Long Tom. Some men shoveled dirt, rocks, and gravel while others took out big rocks as the material was moving along. Twice daily the gold and sand would be caught on the riffles removed and panned.