A gully, rectangular in cross-section, cut into debris-choked valleys, usually with a sandy floor, made of fine-grained cohesive sediments in arid environments. It results from the entrenchment of stream channels when run-off increases. Badlands are associated with arroyos. Perroy et al. (2012) AAAG 102, 6, 1229 untangle the relative importance of climatic, tectonic, and anthropogenic drivers as triggers of arroyo formation in California.