Soil production in upland settings is controlled by the rate of rock weathering which in turn is controlled by soil depth such that weathering declines exponentially beyond the depth at which maximum production occurs. However, whether maximum soil production occurs under a shallow or non-existent soil cover remained unresolved until recently.

Cosmogenic radionuclide measurements in bedrock can be used to test theoretical models of soil production. Early results from south-eastern Australia indicate that maximum soil production occurs under near zero soil cover at rates of 10-70 m/Ma or more. This result is contrary to the long held view that maximum soil production takes place under a shallow soil cover. Regardless of the soil production model, however, it appears a metre of soil can be produced in under 100,000 years in upland SE Australia. This implies that rates of soil formation, i.e. rates at which soil material is organized pedogenically, are operating at rates at least as fast as soil production.

Developments in optically stimulated luminescence dating provide a basis for exploring the speed of pedogenesis. Small aliquot and single-grain dating of quartz sand grains indicate that soil material is turned over much faster than soil production rates by 2-3 orders of magnitude. To date mixing is largely attributed to bioturbation in warmer settings and to cryoturbation in colder areas. The role of shrink-swell has yet to be tested this way.

Collectively these results challenge the way in which soil systems are viewed since many pedogenic features are likely to have developed quickly and recently.