Salt of the Earth

Years ago, I stopped eating lunch with other staff.

It wasn’t that I was standoffish, although I have been accused of that. Rather, it was because I tired of the chastising comments about my use of salt. Granted, I may consume too much sodium chloride — my kids claim I salt my ice cream — and that probably isn’t good, but I didn’t like being reminded of my bad habits.

However, I am not the only one who finds a use for salt. In fact, table salt makes up only 17 percent of salt use. For example, with winter setting in, many communities are preparing to fight back by using salt to keep roads ice-free. Idaho is one of 26 states that use salt to maintain ice-free roads. The salt works well if applied in appropriate amounts, dropping the freezing point of water to 7 below zero.

Idaho Department of Transportation uses 138 million pounds of salt and salt brine on 12,000 lane miles of road each winter. Individual counties and municipalities may add significantly to that total.

Salt — equal parts sodium and chloride — has been part of the human experience since at least 6,000 B.C. Before refrigeration, salt was essential for preserving meat. It was such a valuable commodity that in the 6th century, Moorish merchants traded salt for gold, pound for pound. Some nations used it for currency, actually minting coins from the rock salt. The word, salary, comes from the Latin word for salt. Salt trading routes were established across Africa, Tibet and Europe. A tax on salt was partially responsible for the French Revolution. And the word, salad, comes from the Roman practice of salting leafy veggies.

We know the ocean is salty and that places like the Great Salt Lake and the Dead Sea are saltier still. How did they get that way?

It all starts well back on land where water drains from the highlands. Through chemical and physical erosion, minerals are dissolved from soils and rocks. These minerals, including salts, are carried downstream and deposited in oceans or lakes with no outlet such as Great Salt Lake. Scientists calculate that two million tons of minerals flow into Great Salt Lake annually and add to the 4-5 billion tons already there.

Salt is harvested from the ocean, mineral springs, terminal lakes and from huge sedimentary deposits. These sedimentary deposits were laid down over millennia as inland seas formed. Like the Great Salt Lake, minerals flowed in and the seas eventually evaporated leaving behind thick layers of salt that were later buried with soil.

The sedimentary layers are often enormous. One of the largest deposits is in Pakistan. This mine has 19 stories, 11 of which are underground, with 250 miles of passages. And, although this mine has been operating since at least the 12th century, it is expected to last at least another 350 years at current extraction rates.

So how much salt is out there? The ocean has about 35 parts sodium per thousand parts water. That is about eight times less than the 300 parts per thousand in the Great Salt Lake. However, if you were to dry out all the salt in the oceans and place it on dry land, it would entomb everything under 500 feet of salt.

Salt is an essential mineral for all animals. I suppose there is also the possibility of too much of a good thing. But at this holiday season, I try to live by the motto, all things in moderation, including moderation. It has seen me through this far.

Terry Thomas is a wildlife biologist and naturalist with 30 years of experience. “The Best of Nature,” a collection of more than 100 of Thomas’ best nature essays is now available. Pick up your copy at the Post Register or order one through his website,