By their very nature, Earth materials can be heterogeneous or anisotropic. These characteristics relate to translational or rotational invariance, which makes them inherently scale dependent. Heterogeneity or anisotropy at a given scale emerges from the intrinsic properties of the solid and fluid constituents at a smaller scale, their geometrical attributes and structural arrangement. Therefore, anisotropy or heterogeneity can be preserved, or not, across scales. The aim of this session is two-fold: (1) Record current knowledge on heterogeneity, anisotropy and scale-dependency of the physical and mechanical properties of Earth materials; and (2) Showcase how accounting for these complexities can help shed light on Earth’s specific features and processes. Given that heterogeneity and anisotropy can be detected at various scales and for various material properties, contributions are expected to span a broad spectrum of solid Earth disciplines, from direct observations (laboratory, field) through to discernment of the underlying physical processes via modeling.