Shoalhaven District Geology

FIELD GEOLOGY OF THE SHOALHAVEN DISTRICT (PART 23) CHAPTER 15: THE CLYDE RIVER VALLEY T aking its rise at an elevation of 2,500 feet near Sassafras, this small river flow south and descends by way of a great canyon to a level of 200 feet at Yadboro. It does this in less than 20 miles, yet it is a further 40 miles to the sea downstream. This is a peculiar result of the dip of the Shoalhaven group sediments. At one time, these must have extended further south than at present. When the area was uplifted, it was tilted to the north, so that the ancestral Clyde River had to erode its bed against this trend.  This undoubtedly led to the formation of many waterfalls and the evolution of the canyon upstream from Yadboro.  The southern edge of the sandstone scarp presents a bold face and is broken into numerous outliers. Some such as The Castle and the Pigeon House are well known to bushwalkers, but there are many others. They all have a similar structure, being capped by cliffs of the...

  FIELD GEOLOGY OF THE SHOALHAVEN DISTRICT (PART 20) CHAPTER 12.  The Milton-Ulladulla District   The Milton intrusion dominates the geology of this part of the country. Its rich soils lie conveniently close to Ulladulla Harbour and settlers began to arrive here about 1830. However, apart from the country underlain by the Milton Monzonite, the rest of the landscape has changed little since Cook first viewed it in 1770.  Apart from the igneous rocks near Milton, The Conjola Formation is dominant in this area. In recent years there has been a revision in the nomenclature of the Formation and it is now known to consist of sediments of widely varying ages, all within the lower Permian. Contrary to earlier ideas, the lower beds are equivalent to the lower part of the Dalwood Group in the Hunter Valley. Some parts of what has been called the Conjola Formation are as young as the lower Maitland Group. Research into this aspect of Shoalhaven district Geology is still in prog...

FIELD GEOLOGY OF THE SHOALHAVEN DISTRICT                                              (PART 18) Chapter 10. The Wandandian and Conjola Districts   This is largely an area of uncleared bushland. Features of interest lie along the highway or on the coastal strip. Other than the Wandrawandian Siltstone and the Conjola Formation, the only variation in the geology is provided by an occasional dyke or inlier of basement rocks.  Several dolerite dykes will be seen on these excursions; they are all similar, being composed of a bluish-black olivine dolerite with phenocrysts of plagioclase up to 1 inch across. The dykes are up to 60 feet wide and are traceable for several miles.  The deep valleys of Wandandian and Conjola Creeks have exposed highly folded strata of unknown age, usually taken to be Ordovician like the metamorphic rocks of Tolwong and Nerriga. These have...

FIELD GEOLOGY OF THE SHOALHAVEN DISTRICT (PART 3) Chapter 1: Introduction .  “ The land near the Sea coast still continues of a moderate height, forming alternately rocky points and Sandy beaches; but inland, between Mount Dromedary and the Pigeon House, are several pretty high Mountains, two only of which we saw but what were covered with Trees, and these lay inland behind the Pigeon House, and are remarkably flat a Top, with Steep rocky clifts all round them. ”  Lieutenant James Cook wrote this on Sunday 22nd April, 1770, as the “Endeavour” passed by the Shoalhaven district of New South Wales. Today, the scene has changed little. However we are now able to explain many of these geological features which were of such interest to Cook.  The Shoalhaven district, by which we mean the coastline from Bateman’s Bay to Kiama and inland for up to 40 miles, is of great interest to geologists. There is a considerable variety of rock types and structures because the edge of the Syd...

  FIELD GEOLOGY OF THE SHOALHAVEN DISTRICT NSW AUSTRALIA (PART 2) Part 2 of "Field Geology of the Shoalhaven District" TABLE OF CONTENTS   Note: numbers refer to page numbers in the original typed copy. A Word or Two of Explanation      2    Table of Contents           Chapter 1: Introduction        6  Figures: Location of the Sydney Basin,           7                                       Cross Section of the Basin, Geological Time Scale  Chapter 2: The Kiama District      8   Excursion 2a: Shell Harbour Rail – Kiama – Gerringong 8   Excursion 2b: Gerringong – Berry    13   Excursion 2c: Kiama – Robertson – Fitzroy Falls  14   Questions        16  Chapter 3: The Nowra D...