The geoheritage and geomorphology of the sandstone pagodas of the North-western Blue Mountains Region (NSW)

The towered `pagoda¿ rock formations of the north-western Blue Mountains, west of Sydney, have aheartland of about 600 km2, mostly at around 1000 metres altitude in Banks Wall and Burra Moko HeadSandstones. The pagodas are of two types: the `platy pagodas¿ are generally stepped-cones in shape, withsemi-regular ironstone bands, whereas the `smooth pagodas¿ display less ironstone bands and are similarto many slickrock slopes found elsewhere. The platy pagodas however are an uncommon and signifi cantgeomorphic landscape feature, and are distinguished by the extent and regularity of their ironstone banding.The formation of the ironstone banding has involved the movement of iron in solution and its precipitationto form resistant bands, swirls and pipes. Questions remain as to how the ironstone banding formed,however `roll fronts¿ of reaction between reduced Fe2+-rich water and oxygenated water may best explainthe amazing ironstone shapes. The geoheritage value of the pagodas is signifi cant, but is threatened byactivities such as longwall coal mining. The pagodas and the associated slot canyons of the Blue Mountainsare ideal candidates for future geological and geomorphological research.