Stable cratonic regions of Australia are often characterized by stepped landscapes, where relatively flat land surfaces occur at distinct elevations. The relative topographic position of these surfaces, the depth and complexity of their soils and weathering profiles, and their stratigraphic relationships have been used to correlated these land surfaces on a regional, cratonic, and even worldwide scale. ⁴⁰Ar/³⁹Ar dating of minerals precipitated in weathering profiles provides a quantitative means of testing such postulated correlations.

⁴⁰Ar/³⁹Ar dating of more than 500 samples of supergene Mn-oxides (cryptomelane and hollandite) and sulfates (alunite and jarosite) from 13 distinct weathering profiles hosted by surfaces at different elevations in the Mount Isa Region, Australia, indicates that the regional scale correlation between these surfaces is possible. Weathering ages vary according to elevation. The higher elevation weathering profiles (400-500 m) yield the greatest ages (65-70 Ma). Weathering profiles hosted by intermediate elevation surfaces (280-320 m) yield relatively younger results (12-25 Ma), while weathering profiles hosted by the lowest elevation surfaces (160-200 m) yield the lowest weathering ages (0.7-6 Ma). Long-term erosion rates obtained from the differences in elevations and weathering ages between the surfaces range from 2-4 m.Ma^-1.

Erosion rates for the dated Mt. Isa weathering profiles, obtained from cosmogenic isotope (¹⁰Be, ²⁶Al, and ³⁶Cl) abundances, indicate that the lowest elevation surfaces (youngest weathering ages) correspond to the highest erosion rates (2-4 m.Ma^-1). The higher elevation surfaces, hosting the oldest weathering profiles, yield the lowest erosion rates (ca 1 m.Ma^-1). The variation of erosion rates with landscape position accounts for the preservation of older weathering profiles at higher elevations. The variation in erosion rates also suggest that landscape evolution in the areas studied occurs primarily by scarp-retreat and not by a Davisian-style surface ablation. The results also indicate that long-term erosion rates for the Cenozoic, obtained from weathering geochronology, do not differ significantly from Quaternary rates obtained through cosmogenic isotope measurements.