Penn Engineers Propose 'Geomimicry' to Design Materials the Way Soil Evolves

Engineers at the University of Pennsylvania have introduced a framework called geomimicry, which asks how soils, sediments and other Earth-shaped materials acquired their properties over geologic time, and how those processes might inspire more sustainable engineered materials. The team described the framework in a perspective paper published in the journal Physical Review E.

The paper caps nearly a decade of collaboration between Paulo Arratia and Douglas Jerolmack, both professors in Penn's Department of Mechanical Engineering and Applied Mechanics, who had been studying seemingly unrelated questions: why some mudslides flow like sand while others behave like hair gel, how repeated wetting and drying cycles strengthen soil, and why mud collected along the Delaware River gives Major League Baseball pitchers a better grip. That mud, known as Lena Blackburne's rubbing mud, has been a baseball staple for nearly a century, and the Penn team has now scientifically confirmed its friction-enhancing properties.

Lead author Shravan Pradeep, a postdoctoral researcher working with Arratia and Jerolmack, said geomimicry means understanding materials by what they do rather than what they are made of. Rather than asking whether a soil contains a particular kind of clay, the framework asks what that clay does: does it help particles stick together, allow the material to flow, or store and move water? The researchers call these properties mechanical functional groups.

One of the paper's central ideas is that nature does not create soils, it trains them. Unlike manufactured materials, soils spend thousands of years responding to cycles of rain, drought, freezing, thawing, earthquakes, flowing water, plant roots and microbial activity, a process the researchers call environmental training that reorganizes microscopic structures and leaves behind a kind of memory shaping how soils respond to future stress.

Pradeep said a trained farmer can tell whether soil is good simply by feeling its texture, since thousands of years have gone into optimizing the particle sizes and interactions a hand can feel. No two handfuls of soil tell exactly the same story, since each has evolved for its own specific landscape and climate.