The black soil is lignite that was vegetative matter that grew along the floodplain. The grey coloring is mudstone, siltstone, and shale. The red coloring is laterite soil that formed by floodplain deposits when the area was warm and humid.
An abundance of fossil remains of early horses, camels, and rhinoceroses in the Painted Hills unit makes the area particularly important to vertebrate paleontologists.
Painted Hills, Oregon
Bands of laterite give these Painted Hills in the John Day Fossil Beds National Monument near Mitchell, Oregon their colorful appearance.Video by Mary Harrsch