Landscape response to tectonics and climate: a cosmogenic nuclide perspective

Prof. Darryl Granger
Purdue University

It has long been considered in geomorphology that landscapes tend towards a condition of steady-state, where erosion rates approximately equal uplift rates. However, it has been argued that steady-state seldom occurs in nature, primarily due to erosional responses to climate change. Cosmogenic nuclides now offer a method to measure erosion rates through time, and to test for steady-state in a variety of landscapes. I will summarize data collected over the past 10 years to show that erosion rates are remarkably insensitive to climate (in the absence of glaciation), and that they instead match long-term exhumation rates over a range of tectonic settings. A case study from the northern Apennines, Italy, illustrates that even rapidly uplifting orogens can approach steady-state over timescales of millions of years. Finally, a case study from the northern Alps, Switzerland, shows the profound impact that glaciation can have on regional erosion and incision rates.