The authors are among those who have made significant contributions to this scholarship, and they draw very effectively on a wide range of information in telling the story of the Santa Cruz. The book starts with a description of the physical setting of the drainage basin, including geologic history, Holocene arroyo formation, climate and hydroclimatology, riparian ecosystems, and prehistory. This description is followed by

a chapter discussing the potential causes of historic arroyo downcutting and filling during the late 19th and early 20th centuries. The bulk of the book is devoted to a detailed description GSI-IX of historic changes occurring on the Santa Cruz River during the period from Spanish settlement to river restoration measures in 2012, when wastewater effluent created perennial flow in some portions of the river and sustained a riparian ecosystem. The authors use historical and, to a lesser extent, geological and paleoecological data, to reconstruct the physical and cultural conditions in the region during the past three centuries, a period that includes a time Selleckchem AZD5363 of substantial arroyo downcutting. This channel downcutting is the primary historical change emphasized in the book, but physical channel changes are presented in the context of biotic and human communities along the river.

The authors carefully describe the riverine characteristics before arroyo downcutting, how and when the arroyos formed,

and the continuing effects of the arroyos on contemporary floodplain management. The book also focuses on the historical existence of the Great Mesquite Forest. This riparian forest included such large, old cottonwood and mesquite trees that numerous historical sources comment on its characteristics. The forest, which covered at least 2000 ha, began to decline during the 1930s and 1940s as a result of water table declines associated with groundwater withdrawal, and crossed a threshold of irreversible to loss by the early 1970s. The main text concludes with a summary of past riverine changes and a discussion of some possible river futures. A series of appendices following the main text includes lists of historical and contemporary species of birds, amphibians, reptiles, mammals, and plants along the river, as well as threatened and endangered species, and ornithologists who have studied bird communities along the river. The appendices are followed by extensive end notes and references. This book tells a complicated story. As the authors explain, the historical Santa Cruz River was mostly dry between floods except for relatively short spring-fed reaches. This condition contrasts with the romanticized view that has become popular, of a perennial historical river that created ‘a land of milk and honey’ in the midst of the Sonoran Desert. This is one simplistic view of past river environments.