Geomicrobiology: the interdisciplinary study of the interactions of microorganisms and earth materials. This concerns the role of microbe and microbial processes in geological and geochemical processes. The field is especially important when dealing with microorganisms in aquifers and public drinking water supplies. Geomicrobiologists study microbial interactions within and between various earth materials in the geosphere, such as rocks, minerals, soils, and sediment, in the atmosphere and in the hydrosphere.