Howard et al. (1994) J. Geophys. Res. 99, primarily on the basis of bed morphology, define five channel types: live bed sand alluvial; live bed gravel alluvial; threshold gravel alluvial; mixed bedrock-alluvial; and bedrock. In a study of mountain drainage basins, Montgomery and Buffington (1997) GSA Bull. 109, 5 distinguish seven types: colluvial and bedrock, plus five alluvial channel types (cascade, step-pool, plane-bed, pool-riffle, and dune-ripple). Heritage et al. (2001) J. Geol. 109 use cluster and discriminant analyses to classify: bedrock anastomosed, mixed anastomosed, pool-rapid, braided, and alluvial single-thread. These channel types fit on a continuum from bedrock-dominated channels to fully alluvial systems.