Rock avalanches have been widespread in the Karakoram Himalaya. More than 100 events have been identified in recent surveys and they include the largest catastrophic landslides known in the region. Some occurred in the present-day glacierized zone and during the past decade. Most have been identified and reconstructed from more or less ancient deposits at lower elevations. The incidences of these deposits and features that place them in the general class of rock-avalanche fragmentites are described. However, the main focus is on certain morphological and sedimentary phenomena that reflect interactions of rock avalanches with rugged terrain. In most cases, relations between runout path and geometry of opposing valley walls and interfluves have had major effects on the overall shape, surface morphology, and internal structures of the deposits. In some cases there are complex interactions with erodible substrates. Further complications arise from later erosion and burial of rockavalanche deposits, and the large changes they bring about in other geomorphic conditions. Styles of rock avalanche are proposed based upon the configuration of depositional complexes and their relations to surrounding topography, especially to local valley systems. The analysis and terminology for such topography-constrained forms are developed, in particular, from the work of Albert Heim. An understanding of these forms provides a useful guide to field identification and reconstruction of past rock avalanches in rugged mountain valleys, and necessary background for assessing future risks from catastrophic landslides.