The physical properties and the rheological response of polycrystalline rocks of the cryosphere and lithosphere to pressure and temperature, stress and strain is governed by their composition, microstructure and texture.

Microstructure and texture are particularly sensitive to deformation: particle shapes adapt to the imposed strain, grain size reflects the flow stress, the size distribution the intensity of comminution; typical crystalllographic preferred orientations develop as a result of strain or recrystallization processes, etc..

The range of deformation processes and mechanisms can best be identified on the microscale but will control the behavior of the whole system. That is why microstructures provide valuable clues for the deciphering of the rocks mechanical history or current physical state and to infer active deformation processes in nature and experiment. Using microstructural evidence, naturally deformed rocks can be interpreted in the light of results gained from carefully designed experiments carried out under controlled conditions.

This session will combine results from earth and material scientists who use experiments, theory, and natural examples to study the physical properties of Earth's materials (PPEM). Some of these properties can be expressed as constitutive laws, which may be used to describe and extrapolate driving forces, deformation, and their interaction at all scales of observation.