Lake Corangamite is situated approximately 25km west of Colac and 50km east of Camperdown. The Earth Cache is located just outside of the small township of Alvie.
Lake Corangamite, a hypersaline endorheic lake, is located near Colac in the Lakes and Craters region of the Victorian Volcanic Plains of south-west Victoria, Australia. The lake's salinity levels have increased dramatically as the lake level has dropped in recent decades. It is Australia's largest permanent saline lake, covering approximately 230 square kilometres (89 sq mi) with a circumference of 150 kilometres (93 mi). It forms part of the Ramsar-listed Western District Lakes wetland site.
Sodium chloride
Sodium chloride, also known as salt, common salt, table salt or halite, is an ionic compound with the chemical formula NaCl, representing a 1:1 ratio of sodium and chloride ions. Sodium chloride is the salt most responsible for the salinity of seawater and of the extracellular fluid of many multicellular organisms.
The waterbody is surrounded to the south and east by rocky outcrops (known locally as the stony rises) which were formed by lava flows from Mount Porndon to the south-west and Mount Warrion to the east. The spectacular 'Red Rocks' maar crater complex overlooks the south west shore. The Mount Warrion flows caused the lake to form by blocking drainage to the east. As is typical of lakes in the area, the eastern flanks of the lake consist of lunettes formed by wind borne sediments blown from the lake during periods with dry climates.
Flow into the lake is extremely variable and negligible in the driest years. Currently it is endorheic (there is no outflow) but during the wet decade of the 1950s the lake flooded and became connected via a series of wetlands and lakes to Lake Murdeduke and the Barwon River. It has never been completely dry since European settlement, and there it is evidence it was an open lake for centuries prior to the 1840s when rainfall and runoff were similar to those of the 1950s.
The main inflows are from Pirron Yaloak Creek flowing from the Otway plains to the south, the Woady Yaloak River flowing from the flanks of the Victorian Midlands to the north, and Salt Creek flowing from the plains to the north-west. The Pirron Yaloak has high nutrient loads due to dairy farming in its catchment.
In response to the floods of the 1950s, the Woady Yalloak was diverted away from Lake Corangamite and into the Barwon River. The diversion is managed on the basis of a trigger level for the lake, above which the diversion is enacted. This has not occurred in recent years. Levels have been dropping for decades and it is possible that it will dry completely. In 1980 the salinity was approximately that of seawater and has since risen at least four times that of seawater
Q1 Close to the listed coordinates you will see an information sign. What type of shells line the lake and form the shoreline?
Q2 Explore the area. Describe what you see. Can you find any of these shells? Describe the type of shell it is.
Q3 WP2 will take you to some rocks. Describe the colour and texture of these rocks.
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. Hope you enjoy it. Feel free to attached photos to your log (optional).