Shoalhaven District Geology

  FIELD GEOLOGY OF THE SHOALHAVEN DISTRICT (PART 15) Ettrema and Beyond – the Great Gorges. Excursion 9a One must never underestimate the erosive power of running water. Almost as fast as the uplifting process begins, many streams large and small begin to level the land again. Nowhere is this better seen than in the gorge country west of Nowra, where scrubby sandstone plateaux give way to great canyons, and tinkling waterfalls demonstrate the ceaseless battle between the two. Ettrema Gorge January 1969 From sea level at Nowra, the sandstone surface rises, almost imperceptibly, to a height of 2,500 feet in the west. The Shoalhaven River and its tributaries have removed this resistant layer along their courses and exposed the older rocks below. Unlike Kangaroo Valley, these gorges have little to attract the settler since their few level areas are comparatively infertile and access is difficult indeed. It has taken the discovery of minerals – gold, silver, and lead – to cause man to d...

  FIELD GEOLOGY OF THE SHOALHAVEN DISTRICT (PART 11) Chapter 6  The Yalwal and Burrier Districts   Scattered throughout Australia are numerous ghost towns. Yalwal is such a place, but time has removed all but a trace of the town itself and left only the mines which once brought prosperity.  That famous cleric-cum-geologist, the Rev. WB Clarke, noted the existence of gold here as early as 1852. He reported that fine gold was to be found in Danjera and Yalwal Creeks, recommending further prospecting to the local settlers. The ‘golden era’ began in 1872 and lasted into the present century, with minor revivals ever since.  The Permian strata rise gradually to the west, exposing the basement rocks in all valleys west of Grassy Gully. The oldest strata are comparable to those known to be of Ordovician age and consist of altered clastic sediments. These are exposed only in parts of Danjera and Yarramunmun Creeks. They are overlain by sandstones and conglomerate, contai...