Rock strength controls erosion in tectonically dead landscapes.

Interactions among tectonics, climate, and lithology shape the Earth's surface. In regions dominated by tectonic quiescence and climate stability, the role of rock strength related to lithology, and its role in landscape evolution, can be most clearly perceived. We leverage these qualities in a unique field site by integrating topographic data, erosion rates, and a large suite of rock strength measurements to quantify the relationship between bedrock strength and erosion rates along a 200-km section of the southeast coast of Brazil where climatic and tectonic variability are minimal. Our findings reveal a 20-fold erosion rate variation best explained by differences in rock strength. We also demonstrate that incorporating lithological strength variability into the analysis of landscape incision substantially improves accuracy, with outcomes that better reproduce natural settings. Our results underscore the crucial role of rock strength in landscape evolution and emphasize the need for field studies to account for lithological variability and thus accurately interpret landscape dynamics.