GEO History:
Most of the area forms part of the Lachlan Fold Belt which is a complex area of Paleozoic rocks extending northwards from Victoria through south-eastern NSW. These strata have been folded several times in the Paleozoic period. Relatively uniform Permian sediments (280-230 mya) of the Sydney Basin overlie the Paleozoic rocks in approximately one third of the area, reaching as far south as Dark Beach, just south of South Durras village. These have produced sandy beaches, wave-cut platforms, regular cliffs and headlands and offshore islands. The area contains sites of geological significance. The Snapper Point Nursery Bed between Pretty and Merry Beaches is an outstanding record of trace-fossils, including the oldest record in the world of decapod fossils. They are an important record of palaeoclimate, palaeogeography and sedimentation processes in the early stages of the formation of the Sydney Basin. The sediments here and at Pebbly Beach and Wasp Head contain a diverse and rich fossil assemblage of bivalves and brachiopods. Plant and marine fossils from these locations have provided important information on the Permian flora and fauna within the Sydney Basin. This has assisted in the understanding of the evolution of the Australian flora and changes in environmental conditions since the Permian era (REF: Australian Heritage Commission, 1983).
Other significant geological features include:
- sedimentary breccia in the Wasp Head formation between Myrtle Beach and Wasp Head containing blocks of granitic origin which appear to have been dropped by melting ice floes
- fossil logs in the Wasp Head Formation and at Pebbly Beach
- ironstone boxwork at Wasp Head
- fine examples of differential erosion in a varied assemblage of geological structures at Point Upright.
These geological features are of considerable scientific importance and present outstanding opportunities for teaching and research in paleontology and stratigraphy (REF: NSW National Parks and Wildlife Service, 1998). The Snapper Point Nursery Bed and those at Pebbly Beach and Wasp Head are on the Register of the National Estate. Although now protected within Murramarang National Park, the integrity of the sites has been reduced in some areas by illegal fossil collection.
The EC:
To access to site, park at the indicated area, and walk (South) along the beach towards the rocks. When at the rockshelf, walk along it and look around.
The Questions:
AREA 1
a. Are quartz rocks visible on this section of exposed exposed shelf?
b. What is different about the visible shelf compared to the adjacent exposed bands?
AREA 2
At this location you will find a large cluster of volcanic gas bubbles. They are evident by the circular craters left in the visible rock. They range in size from 200-300mm).
AREA 3
a. A large "structure" is visible to your right (Facing South). Please describe what you see here?
b. At your feet are fossils that extend for another 200m. What is the predominant fossil type?
THE SMALL PRINT:
Please submit your answers as soon as you can. It's ok to post prior, I will check your findings and respond if there are issues. Feel free to add a photo of yourself at the site if you want too. Group visits are encouraged. I hope you enjoy the experience, this is a very special area.