Crust forms as a consequence of planetary differentiation and recycling processes. On Earth, differentiation processes have led to the formation and modification of felsic, evolved crust over time and provide a window into the complexity of crust from the Archean to the present. Near-surface interaction with the biosphere, internal differentiation by tectonic, igneous and metamorphic processes, and recycling into the mantle constantly change the composition of Earth crust. However, we have a limited understanding of the formation, differentiation, and stabilization of the Earth's lower crust and the transition zone between that and the mantle. Recent studies on exposed deep crust, including ultrahigh-temperature (UHT) terrains and the crust–mantle transition, as well as drilling initiatives (such as ICDP-DIVE) are adding novel insights and a new dimension to our understanding of planetary crust evolution and its control on physical properties, redox conditions, volatile elements and georesources such as critical minerals and natural hydrogen. In addition, deep crustal environments may host a range of microbial life that interacts with the chemistry of the crust and influences biogeochemical cycles. We invite submissions aimed at understanding crust-forming and modification processes, using any geological, geophysical, geochemical, geochronological, microbiological datasets and/or geodynamic modelling with the aim of elucidating the 4D evolution of crust on Earth and beyond.