Abstract
<jats:p>Weathering and soil formation have shaped Earth's surface for billions of years, sustaining the long-term productivity of terrestrial ecosystems, with microorganisms linking rock-derived nutrients to the atmosphere and hydrosphere since early Earth. Yet the long-term (centennial to millennial) interactions between microbial communities and geomorphological processes remain largely unexplored. We integrate approaches from microbial ecology (16S rRNA sequencing) with geomorphology (cosmogenic 10Be nuclide dating) to investigate how microbial communities develop and influence surface processes. We compare microbial communities in surface rock, saprolite, and soil across a deglaciated basin and find two distinct trajectories: microbial diversity and functional potential increased with progressive weathering and soil formation in soil-mantled environments, while in surface rock, low-diversity communities persist with little ecological turnover over ~16,000 years. These outcomes demonstrate the tight coupling between biotic and abiotic forces and highlight how microorganisms take part in the long-term surface processes that shape Earth’s surface.</jats:p>