Yorketown is surrounded by more than 200 salt lakes of varying sizes and colours. This earthcache will bring you to Pink Lake. The salt lakes are ephemeral, depending on the season and the run of weather they may be wet or dry.
Salt lakes form under four geomorphological conditions. South Australia has all four of these conditions depending on the location.
- Large closed basins with extensive internal drainage area. Lake Eyre, Lake Frome and Lake Torrens are typical examples.
- Small closed basins with small internal drainage basins. Shallow saline water tables, drainage and high evaporation rates contribute to the formation of the lakes.
- Crater lakes form in lava fields known as Maar. There a several crater lakes south east of Mt Gambier. The salinity depends on the balance of precipitation and evaporation.
- Coastal lakes like the Pool of Siloam at Beachport. These saline lakes form behind dune barriers and are subject to variations in sea level and water table.
The pink colour of the water and salt comes from a pigment secreted by microscopic algae. A microscopic algae called Dunaliella salina is common in the open water of the lakes. The algae grows on salt crystals. This algae contains beta-carotene, a red/orange substance which is responsible for the pink colour of the lakes.
Earthcache Tasks
- Describe the colour of the lake. Compare the colour to the lake at the town lake (Ref WP). Why is there difference in colour?
- What type of geomorphological condition has formed the lakes?
Acknowledgement: Australian salt lakes, Patrick De Dekker