Q:
A: Salt! The Chott El Jerid is a dried-up lake, 250 km long and 20 km wide. The surface of the Chott is composed of myriad salt crystals which have formed a sufficiently resistant and thick layer resting on a layer of clayey mud or waterlogged sand. In some places the water covers the salt crust which then becomes less thick, but the intense evaporation and the winds rapidly dry the surface out. This is the Lake Triton, famed in many legends, the sacred lagoon famed in many fantastic tales, and it was known to ancient writers, who nevertheless, charted an incorrect geographical location. Pliny and Herodotus mention it, Western travellers discovered it and tried without success to make the sea flow into the deep desert. Mirages dance across its surface when the temperature exceeds 30 degrees. Nowadays, it is used for speed sailing