Thursday 29 August 2024
Photos courtesy of Tony and DonnaG, Helen and Martin, and Max. Walk report courtesy of Walk Leader Rob.
After a blustery week perfect weather arrived for the Ulladulla Geology and Fossil Walk. This is a Social Walk that mixes an Easy walk, a bit of geology education and a pub lunch. The walk is located in Brodie Park , Ulladulla and consists of a ‘time walk’ where large pieces of geologic rock from different locations on the south coast have been positioned along a paved walkway, separated by a distance to represent their formation over the last 500Million years. Each sample is well documented and information signs give readers a good description of what was happening at each period of time. I think its safe to say everyone learned a few new facts about the geology of the south coast and peppered the walk leader with many interesting and challenging questions.
We then headed down to the harbor next to the sea pool for an exploration of the fossils seen in the siltstones exposed at low tide on the wave cut platform. Once the walk leader had shown the walkers what the fossils looked like they were off like excited school kids finding many good examples across the platform. Many of the walkers were surprised to hear that when the fossils were sea shells and corals alive on the floor of a shallow sea this part of the Australian coastline was located at about 65 degrees latitude south and the water temperature was less than 5 degrees. Glaciers and melting icebergs ‘dropped’ rocks into the sediments that were then covered by over 800m of sedimentary rock which has eroded away over the last 200Million years to be now seen today on the shores of Ulladulla Harbor.
Everyone now knows the lost microplate ‘Zealandia’ that broke off from Australia 100Million years ago is under the waters of the Tasman Sea and its parting act was to create the stress fracture pattern seen on the shores of the Ulladulla harbor rock platform.
There will be a test at the Christmas party but the crib notes can be found at www.gondwanacoastfossilwalk.com.au.