Low variability runoff inhibits coupling of climate, tectonics, and topography in 1 the Greater Caucasus 2 The influence of erosion thresholds and runoff variability on Global analysis of the parameters

Hypothesized feedbacks between climate and tectonics are mediated by the 28 relationship between topography and long-term erosion rates. While many studies monotonic relationships between channel steepness and erosion rates, the degree of nonlinearity in this relationship varies by landscape. Mechanistically explaining controls on this relationship in natural settings is critical because highly nonlinear relationships imply low sensitivity between climate and tectonics. To this end, we present a 33 coordinated analysis of cosmogenic 10 Be concentrations in river sands paired with topographic, hydroclimatic, and tectonic data for the Greater Caucasus Mountains where topography is invariant along-strike despite large gradients in modern precipitation and convergence rates. We show that spatial patterns in erosion rates 37 largely reflect regional tectonics with little sensitivity to mean precipitation or runoff. The