A large and increasing data base of apatite fission track results from sedimentary and granitic rocks exposed within
the southeastern highlands and along the continental margin of Australia provides constraints for the tectonic
development of the southeastern passive margin. The fission track results suggest that many regions of the
southeastern margin of Australia experienced distinct episodes of relatively rapid cooling during the middle
Cretaceous to early Tertiary that can be attributed to the effects of rifting. One cooling episode is middle Cretaceous
in age and related to denudation of the southeastern highlands from Tasmania to northern New South Wales between
-90-100 Ma. Rocks exposed along the present coast line record a later episode of rapid cooling, which is
diachronous and decreases in age northward from -80 to 90 Ma in northern Tasmania to southern New South Wales,
-60-80 Ma in central and northern New South Wales, and to -50-60 Ma in southern Queensland.