Book excerpt: Published by the American Geophysical Union as part of the Geophysical Monograph Series, Volume 107. Bedrock river channels are sites of primary erosion in the landscape, fixing the baselevel for all points upstream. This volume provides for the first time an integrated view of the characteristics and operation of this important, though hitherto neglected, class of channels. Examples are provided from several continents and cover a wide range of spatial scales from the large river basins (such as the Colorado River in the United States and the Indus River in Pakistan) down to reach scales and individual sites. Likewise the geologic timescales considered range from erosion and transportation during individual flows to accumulated effects over periods of tens of millions of years.