Earth and planetary surfaces are playgrounds of fluid-granular mixtures which produce patterns, exotic phase transitions, hybrid states of matter, and instabilities in landscapes. These interactions are in some ways ubiquitous; research efforts in other branches of science (i.e. physics, engineering) are also concerned with the details of collective dynamics of discrete particles. Various measurement tools/techniques, theories and frameworks have emerged to account for dynamics, but rarely are these approaches ported outside of these disciplines and applied in a geophysical/geomorphological context. In this session, we welcome contributions that make such applications. Problems related to transient dynamics (e.g. instabilities, segregation, creep) and traversing discrete to continuum scales are of particular interest. Experiments, fieldwork, modeling, remote sensing and theory pertaining to any landscape type and particle/fluid flow (e.g., with sediment, snow, and lahar flows) are welcome.