The structural geology of over 100 km**2 of Cretaceous rocks in the southeastern Blue Mountains is described for the first itme. Full stratigraphic details have yet to be resolved, but it is apparent that the structural evolution was contolled by different responses to deformation of the two dominant rock types. These are a thick massive unit of basaltic volcanics and a thinly bedded sandstone/siltstone/mudstone sequence, separated by thin limestones. Synsedimentary deformation is recognized at the boundary of well-bedded argillaceous and thick arenaceous units. Tectonic folds have a dominant NW-SE trend, but variations exist within a mosaic of structural domains. Three fault trends are recognized. Refs.