Salt of the Earth

Warm and salty, the lagoons of Baja California Mexico are not just ideal nurseries for gray whale babies. These lagoons also offer ideal conditions for producing solar-evaporated salt. They are apart from the sea. They receive very little rainfall and almost no freshwater runoff. The winds are brisk and persistent.

Laguna Ojo de Liebre's 75,000 acres of evaporating salt ponds are home to the world's largest solar saltworks. The salt is produced by Exportadora de Sal, S.A. de C.V. (ESSA for short). With headquarters in the town of Guerrero Negro, the company is jointly owned by Japan's Mitsubishi Corporation and the government of Mexico. About half the salt exported from the Guerrero Negro saltworks is used in Japan's industries to help produce PVC plastics, bleach, chlorine gas, road salt, and glass.

The photos below show some steps in salt production. Does any of this salt end up in your salt shakers or on your icy streets in winter? In the activity that follows, discover how salt beds are formed and relate your results to the photos below.

Salt Production at Laguna Ojo de Liebre
It looks like the Antarctic, but it's the salt evaporation ponds near the town of Guerrero Negro, Mexico. Pumps suck lagoon water out at a rate of 528 million gallons per day. gwhale_Mexico062
Over time and under the hot sun, water evaporates from almost 50 crystallization ponds and 18 concentration ponds. gwhale_Mexico063
Machines dig out the salt and break it up. A six-story dune of salt waits for loading. gwhale_Mexico044
The crystallized salt from trailer trucks goes into the washing area, then a conveyor belt moves the salt to pile it up. gwhale_Mexico054
Barges like this one carry salt out to Cedros Island, where a million tons await shipping on the ocean to distant ports. gwhale_Mexico039

Try This! Create Mini-Saltbeds

Materials Needed
Table salt
Glass bowl, 2 qt. (2 liter)
Measuring spoon for a tablespoon (15 ml)
Measuring cup, 1 cup (250 ml)

  1. Decide whether students will work in pairs, small groups, or individually, or whether this will be a class demonstration.
  2. Stir together in the bowl 1 cup of water and 4 tablespoons salt.
  3. Allow the bowl to sit undisturbed until all the water evaporates. This may take 3 to 4 weeks.
  4. Make predictions in science journals before and during the process about what will happen.
  5. What can you see in the photos above that corresponds to what happened in your experiment? (For example, which photo shows where climbing clumps of frosty salt were formed as water rose up the sides of the pond and the salt in the water crystallized as the water quickly evaporated?)

Try This! Discussion or Journaling Questions
  • Why do you think crystals line the bottom of the bowl, while white frosty deposits appear on the inner sides of the bowl?
  • How could you find out where the salt in your kitchen come from?
  • How do you think each of these factors helps make the Baja lagoons so ideal for solar salt production?: The lagoons are isolated from the sea, they receive very little rainfall and almost no freshwater runoff, and the winds are brisk and persistent.
  • What effects might the saltmaking operation have upon the whales and the sea birds that come to winter in the lagoons each year?
  • If you lived in Guerrero Negro, you would probably work for the saltworks or make your living fishing. How might various groups feel about the preservation of wildlife habitat and the Baja ecosystem?

National Science Education Standards

  • Materials can exist in different states?solid, liquid, and gas.

National Geography Standards

  • The physical and human characteristics of places.