Although many studies on fungi and geological processes have been published in recent years, books and congress proceedings on geomicrobiology focus mainly on prokaryotes and algae. Therefore, it is the aim of this review to summarize data on the fungal impact on geological processes. These processes include the alteration and weathering of rock and minerals, the accumulation of metals, and the conversion of fossil organic carbon. Fossil records and fungi in subsurface environments are also discussed. This article especially emphasizes the role of epi- and endolithic black meristematic fungi, discussing their deteriorative potential on rock as well as their taxonomy and phylogeny. Moreover, the impact of fungi on weathering of monuments and building materials is described and new methods to study fungi-material interactions are presented. The data summarized here show that "geomycology" is a highly interesting discipline in view of basic geological research, as well as biotechnological application.