Last summer, my parents visited a lot of national parks, including Badlands National Park in South Dakota. They showed me all the fossils they saw, which were really cool, but they also showed me photos of the iconic red banding in some of the rock formations there. These bands are part of the Brule Formation, which formed around 30 million years ago, during the Oligocene, as forest transitioned into savanna.
The red layers are all paleosols, which formed on a “broad, aggrading floodplain“. These developed slowly, and are interspersed with the white layers, which are channel and overbank deposits. Paleosols, as ancient soil deposits, are generally characterized by root traces and soil horizons. Personally, I just thought it was really cool that the paleosols here help to create such beauty in this landscape, and are a very recognizable feature here.