Solid waste geomorphology: A new classification of anthropogenic gravitational processes

The rapid growth of municipal solid waste and plastic production has led to the widespread accumulation of anthropogenic debris across terrestrial, coastal, and marine environments. While traditionally considered an environmental pollutant, large waste deposits increasingly behave as geomorphological materials capable of interacting with Earth surface processes. Here, we propose a conceptual framework that recognizes solid waste as a distinct Anthropocene geomaterial and introduces a hierarchical classification of waste-driven geomorphological processes. The framework integrates four interconnected levels: (i) transport-driven accumulation systems, including litter blooms, garbage patches, and windrows; (ii) anthropogenic depositional landforms such as plastic berms, debris ridges, and litter-generated dunes; (iii) mass-loading systems represented by landfill slopes and coastal waste piles; and (iv) gravitational processes, including waste slides, landfill slumps, debris flows, avalanches, and creep. These processes are linked through a waste geomorphological cascade. By extending classical geomorphological classifications to include anthropogenic materials, this study demonstrates that waste deposits can generate previously unrecognized forms of slope instability and sediment redistribution. Documented landfill disasters worldwide further demonstrate the hazard potential associated with these processes. The recognition of solid waste geomorphology as an emerging field provides a new perspective for understanding the role of anthropogenic materials in landscape evolution, hazard assessment, and environmental management. As waste continues to accumulate globally, its influence on geomorphological systems is expected to increase, requiring integrated and interdisciplinary approaches within Earth system science.