Red beds (or
redbeds) are
sedimentary rocks, which typically consist of
sandstone,
siltstone, and
shale that are predominantly red in color due to the presence of ferric oxides. Frequently, these red-colored sedimentary strata locally contain thin beds of
conglomerate,
marl,
limestone, or some combination of these sedimentary rocks. The ferric oxides, which are responsible for the red color of red beds, typically occur as a coating on the grains of sediments comprising red beds. Classic examples of red beds are the
Permian and
Triassic strata of the western United States and the
Devonian Old Red Sandstone facies of Europe.