Poocher Swamp
For more than 25 million years, the area now known as the Limestone Coast lay beneath the Southern Ocean. Tonnes of marine crustaceans and shells fell to the ocean floor, cementing together to form the soft, white porous rock known as limestone.
Welcome to Poocher Swamp, approx 8.5kms west of Bordertown.
When the sea retreated about 1 million years ago, nature’s chemistry blended the remaining sand dunes and limestone deposits into a labyrinth of caves and sinkholes.
These sinkholes, also known as runaway holes unobtrusively absorb water during rain periods, but the full extent of them is really only apparent when it is dry. The overflow from Poocher Swamp flows westwards along a route which brings into operation a system of unique runaway holes which recharge the underground water supplies. The town of Bordertown relies on these sink holes for its town watersupply.
In wet winters the spectacular runaway holes can be viewed in action. Despite huge volumes of water pouring in, sometimes for weeks on end, the water level in the holes remains constant.
The Poocher Swamp is an excellent example of one of the larger runaway holes in this part of the Limestone Coast area.
The Fresh water lens: The groundwater level at Poocher Swamp is relatively shallow with the fresh waters lens extending 3 kms beyond the swamp. The salinity level is such that this water is suitable for drinking however the deeper the water the more saline it becomes.
The answers to all of these questions can be found on an information board at Poocher Swamp. Please email your answers to me for validation before you claim this Earthcache.
Q1. What is the name of the river that flows into Poocher Swamp?
Q2. Poocher Swamp ground water level is ____ meters?
Q3. What is the level of salinity at Poocher Swamp which allows the water to be drinkable?.
Q4. Describe what a freshwater lens is? Include the meaning of a convex layer of freshwater.
Congratulations to Muff1 FTF