Rheological differences between Archaean and younger crust can determine rates of Quaternary vertical motions revealed by fluvial geomorphology

Abstract

Surface uplift is widely observed in subaerial regions of continental crust that are distant from plate boundaries, often revealed by river terrace staircases with altitude ranges of several hundred metres, which typically span the Quaternary. This characteristic geomorphology has been explained by forcing of flow in the weak lower-crustal layer by surface processes: non-steady-state erosion and cyclical loading by ice-sheets and sea-level fluctuations. This study tests this interpretation, by showing that analogous river-terrace staircases are absent in Archaean crust, which lacks the weak lower-crustal layer found elsewhere.