Atomic to nanoscale structures of rocks, minerals and fluids control the physical and chemical properties of the Earth. Examples of this include: (1) the link between atomistic motion of crystallographic defects through mineral grains and rheological behaviour of the Earth’s mantle, (2) the influence of nanogranular deformation on the stability of seismically active fault zones and (3) the observations that fluids confined in tiny spaces exhibit vastly different physicochemical properties than their bulk counterparts. We are at the dawn of a technological revolution that allows us to study Earth’s materials at scales down to the sub-nanometre level. Macroscopic descriptions fail to explain the behavior of Earth materials. It is only by investigating these materials at the tiniest length scales that we can begin to unravel increasingly complex processes (e.g. dissolution-precipitation, exsolution, coherency stress, fluid-rock interaction, defect motion etc.) with geological scale implications. In this session we welcome contributions that adopt a broad variety of experimental and numerical techniques as well as methods focused on resolving submicrometric to nanometric scale processes that could not be unraveled at the macroscopic scale of observation.