Salt deposits, including those made of the mineral halite, are primarily formed through the process of slow evaporation from enclosed bodies of salt water.
The Evaporation Process
One significant way that salt deposits are created involves bodies of water rich in dissolved salts that become isolated from larger water sources, like oceans. Over time, under suitable climatic conditions (often warm and dry), the water in these enclosed basins begins to evaporate.
Here's a simplified look at the process:
- Enclosed Basin: Saltwater is trapped in a depression or basin with limited or no inflow and outflow.
- Evaporation: Water molecules turn into vapor and rise into the atmosphere, leaving the dissolved salts behind.
- Concentration: As evaporation continues, the remaining water becomes increasingly concentrated with salt.
- Precipitation: Once the salt concentration reaches a saturation point, the dissolved salts begin to crystallize out of the water.
- Drying and Deposition: Eventually, the body of water may dry out entirely, leaving behind layers of crystallized salt on the basin floor.
This cumulative process over long periods results in the accumulation of significant salt layers.
Scale and Examples
The scale of these naturally formed salt deposits can be immense. According to reference information, salt deposits can range from a few feet thick to thousands of feet thick. A well-known example of where such large-scale deposits are found is the Mediterranean basin, indicating that massive bodies of salt water dried up in the geological past, leaving behind vast reserves of salt.
These geological formations are a major source for the salt we use today.
