Shoalhaven District Geology

  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...

  FIELD GEOLOGY OF THE SHOALHAVEN DISTRICT (PART 19) Chapter 11   Tianjara and the Little Forest Plateau     Among the landmarks of the Shoalhaven district is the  Tianjara  group of mesas. They lie about 5 miles south of the Braidwood road, near Tianjara Falls. Their flat surfaces, bounded by cliffs and steep slopes make them obvious from all directions, but particularly from the north. They are easily visible from Bundanoon, Saddleback, and Durras Mountain.  Extensive outliers of the Berry Formation cap the coastal hills south from Tianjara Falls to the Little Forest Plateau. This is uninhabited country, used as a military practice area and out of bounds from time to time. The sediments of the Berry Formation are rather coarser than those further north. The presence of the mesas may be due to the peculiar resistance of the strata in this area. Some geographers have suggested that they may be relics of a former land surface, uplifted and lar...