Welcome to the Chevron Folds Earth Cache
I hope you enjoy this beautiful location and incredible geology.
The Chevron Folds are located near the cemetery in Narooma. Travel down Glasshouse Rocks Road and following it until you reach the cemetery. Go to the rear of the south-west part of the cemetery and follow the trail head in the cache waypoints.
These folds are located on Narooma Beach, in the Eurobodalla region of NSW. The remarkable folding pattern exhibited in these rocks is the result of tremendous pressure coming from the Pacific Tectonic Plate's collision with the land: this collision has effectively foreshortened the existing layered rock into a zig zag pattern.
Please take note of high tide as this location may be not accessible & you will need a tool that can take a measurement.
The folds in this area were created when the continental crust of eastern Australia formed along the margin of the supercontinent of Gondwana during the Palaeozoic and early Mesozoic ages. It resulted from an increase in size by gradual external addition of oceanic crust, recycled continent-derived turbidite (material which has been subject to ocean currents), and volcanic activity.
Orogenic belts are associated with subduction zones, which consume crust, produce volcanoes and build island arcs. Eastern Australia is composed of distinct orogenic belts, collectively referred to as the Tasmanides. These long tracts of highly deformed rock were created as a result of tectonic plate movement and are younger than the Gondwana western portion of the continent. When tectonic plates collide something has to give; usually one continent dives beneath the other (subduction zone) and is melded into the earth's mantle. This collision results in huge pressure and deformation of rocks and landscapes.
Orogenic Belt
The Narooma Accretionary Complex is a geological structural region that is the remains of a subduction zone. It attached itself to the Lachlan Fold Belt in the early Silurian period and was moved by the Pacific Plate westwards until it encountered the east coast of Gondwana. The accretionary prism complex at Narooma Beach is in the transition zone between the Narooma Chert and the Bogolo Formation. The Narooma Chert is thought to be part of an old sea floor. The Bogolo Formation contains highly deformed sedimentary rocks and is thought to be Late Cambrian to early Ordovician.
A chevron in geology is a sharply-folded rock formation. Chevron folds are regular folded beds with straight limbs and sharp hinges. Well developed, these folds produce a set of v-shaped beds.
They develop in response to compressive stress. The angles of the folds are generally 60 degrees or less. Chevron folding is helped if the bedding alternates between beds of different make-up. Turbidites, with alternating sandstones and shales, are the typical geological setting for chevron folds to occurs. Chevrons can also form in land deposits, especially where there are sand dunes.
Today you will be exploring the rocks for answers to the Earth Cache
Questions
The posted co-ords will have you at the base of the folds.
You need to look for a fold that is about 1 meter off the ground (picture attached above in the notes)
Q1 Measure the fold on the left hand side of the most visible fold (along the crack line) and send your answer
Take a few steps around to the left
Q2 Describe the full rock here in detail, from the layers you see, directions of the folding rock, colours and texture. What does it feel like?
Once you complete the EarthCache requirements you can post your find without delay, as per the EarthCache guidelines. You will also need to verify your find by sending me a message and provide your answers to the questions.
For a link to my profile, click here - Na'wal
Thanks for visiting this Earth Cache. I hope you enjoy exploring the area.
Feel free to attach photos to your log (optional) but please don't post any spoliers.
References ~ geomaps.com.au & wikipedia