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This paper is the first of a series reporting studies in the genesis of podzols and humus podzols on coastal dunes in a chronosequence that spans >700K yrs. It is concerned mainly with temporal changes in profile morphology across a podzol chronosequence and with brief descriptions of sites chosen for genetic studies. It summarizes the geology, geomorphology and general mineralogy of dune systems at Cooloola and North Stradbroke Island and briefly discusses the effects of parent material, geomorphic component, climate, dune denudation and vegetation on soil development. Its purpose is to provide a field and morphological framework for other papers in the series dealing essentially with laboratory investigations and interpretations of the chemistry, mineralogy and genesis of these subtropical soils.

Thermoluminescence (TL) of quartz grains has been used to date a soil horizon at each of four sites in a chronosequence of freely drained podzols at Cooloola and North Stradbroke Island. The chronological order of the TL dates is in agreement with the sequence of inferred ages based on stratigraphic, geomorphic, denudational and pedological evidence, but at least one of the TL dates is of considerably greater age than the field evidence implies. Possible explanations of this anomaly are discussed. Differences in the nature of the quartz grains and the various pre-treatments used in TL dating were also examined by using a combination of thermogravimetric analysis (TGA), differential thermal analysis (DTA) and scanning electron microscopy (SEM) methods. The DTA showed no dissimilarity among the quartz samples from the different sites, but the TGA results showed significant weight losses for some samples and pretreatments. The SEM method further showed that weight loss is associated with water-sorbing substances (allophanic materials) present as coatings on grain surfaces and/or in cracks within grains.

The Cooloola sand dunes are part of a series of aeolian parabolic dunes that stretch along the east coast of Australia. They form a chronosequence showing increasing weathering, soil formation and water erosion across six geomorphically recognized soil landscapes. These landscapes were recognized from air photographs and further refined on the basis of some 150 auger holes across the dunes. Data about the structure and floristics of the vegetation were collected at the same time. There is a significant body of literature about the Cooloola dunes but there are two areas that have not been satisfactorily considered. First the previous dating which gave inconsistent results has been superseded by single grain OSL dates and second Cooloola has not been considered in a regional context. Here we report the results of single grain optically stimulated luminescence (OSL) analyses for 31 samples for 21 sites across the geomorphic landscapes. The sites were selected near the apex of each dune as this represents the last depositional date and the least disturbed by sand movement.