This book investigates the historical development and environmental drivers behind the rapid erosion of arroyos in the American Southwest since the mid-19th century. Ronald U. Cooke, a specialist in geomorphology and environmental change, synthesizes decades of field observations and historical records to address the causes of gully entrenchment. By focusing on the specific landscapes of California and Arizona, the author provides a structured analysis of how semi-arid terrain responds to both natural climatic shifts and human-induced land management practices. The text serves as a comprehensive examination of the physical processes that have reshaped these fragile valley environments.

Experts recognize this work as a foundational text for understanding the geomorphological history of the American Southwest. Readers frequently note the academic density of the prose and the thoroughness of the author's archival research.