 The Yuba River creates an incision through metamorphic bedrocks, including Mesozoic igneous rocks (granodiorite), Paleozoic phyllite, and slate from the Shoo Fly and Calaveras Formations.Over time, these channels were filled with Tertiary deposits of gravel, large boulders, and sands that were rich in gold.The Yuba River has been heavily influenced by gold mining activity, with lingering effects such as abandoned mines, residual mercury sequestered in sediment, erosion, and alteration of sediment transport through the river system, with resulting consequences to channel structure.