Volcanic debris avalanches (VDAs) emplace characteristically multicolored, hummocky deposits that are typically coarse, unusually thick, poorly sorted, and contain a wider range of components and sedimentary textures than the deposits of other volcanic wet flows. Debris-avalanche blocks, a component unique to VDA deposits (and to some deposits of lahars transformed from VDAs), commonly preserve pieces of recognizable rock units from the source volcano. Rock colors within debris-avalanche blocks can be both highly varied and intense. This is due to the presence of originally multi-hued and interbedded lavas and volcaniclastic units that formed the failed edifice structure, as well as to any clay-rich, hydrothermally altered rocks from the chemically altered edifice core that are included. The somewhat coherent debris-avalanche blocks in VDA deposits are surrounded by more thoroughly homogenized and neutrally colored mixed material, which is matrix material that also contains gravel-size clasts up to meters in diameter. Key characteristics of VDA deposits include areas of highly irregular (hummocky) topography, juxtaposition of rock units having sharply contrasting textures and colors, unstratified deposits of unusual thickness (may exceed 100 m), pervasive fracturing of hard clasts with pieces fitting together like jigsaw puzzles, large clasts that are dominantly angular, polymictic particle mixtures, and the absence of bubble vesicles in matrix material.