FIELD GEOLOGY OF THE SHOALHAVEN DISTRICT (PART 22) CHAPTER 14. The Nerriga District The Permian sediments reach their highest level east of Nerriga and it is in this area that spectacular examples of erosion are most common. Extensive denudation has exposed the underlying basement rocks over a wide area. These are a continuation of the rocks exposed at Yalwal and Ettrema in the north. The Budawang Range reaches a height of 3,711 feet at Currockbilly Mountain and a similar height at Mount Budawang a little further south. This prominent ridge is the backbone of the basement, consisting essentially of a narrow belt of resistant Devonian strata flanked by Ordovician slates. Marine fossils occur in both these groups as well as sporadic mineralisation. Alluvial gold has been extensively mined, but reefs have rarely proved profitable. The core of the area described in these pages is a wild confusion of deep valleys and remarkable sandstone peaks. It is a pl...