Throughout the Tertiary, average rates of erosion of southeast Australia have been uniformly low (about 10⁻³ mm/yr of surface lowering), indicating that this part of the Australian continent did not contribute to a rapid increase in ocean-basin sedimentation over the past 15 or 20 m.y. Somewhat higher Mesozoic rates may be the result of minor tectonism, but explanation for the generally low Cenozoic and Mesozoic erosion rates may be sought in the forest cover and general tectonic stability of southeast Australia over this time period. Australia's gradually increasing aridity/climatic seasonally over the past 20 m.y. has apparently not resulted in higher average rates of erosion of the continent, except perhaps in the very latest Tertiary and Quaternary.