The westward course of bathtub rings (Potash, Utah)

Where does salt come from? And how can I never have wondered that before? The bathtub ring of Lake Mead and the westward course of empire should have got me thinking about this sooner.

I don't mean table salt, evaporated from the sea or mined from the Himalayas or, for all I know, called into being by the high crystalline 'ting' of the salt fairy's magic wand.

I mean road salt, packed in sacks and scattered broadcast onto black ice from Oregon to Labrador. There's no way that's condensed from unicorn tears onto artisan birch bark plates or freeze-dried onto Aztec granite chargers by alpaca-wearing monks in the high Andes.

Bathtub ring from Hoover Dam

I never can remember whether the bathtub ring in Lake Mead is stuff leaching in or out of the water, but seeing as the Vegas water supply is both upstream and downstream of Lake Mead, it's probably academic.

Our water here is really hard with dissolved salts. Mostly not sodium chloride, but its first cousins once removed. Irrigated land gets mineralised - why? Because, again, there are dissolved salts in the water. And where does the water ultimately end up? The sea - which is salty because of all those dissolved salts.

So that's one thing. Then, too, there are all these massive deposits of evaporite minerals like gypsum, borax and, well, salt. Basin and Range valleys are thick with them, from the famous Death Valley 20-mule borax, halite deposits from California to Utah (Bonneville Salt Flats) to the prosaic but practical gypsum works in several places across the Las Vegas valley.

Salt fins in foreground

And when Captain William Manly was chronicling his trip through the dry southwest, he observed a plethora of springs, pools, and waterways. In fact, they were understandably very high on the list of priorities. Some were fine for people to drink from. Others were not, in a variety of ways. They would taste okay but give you an upset stomach, or they were too mineralised, or too mineralised even for the oxen, or 'salt as brine'.

So I'm not sure why it had not occurred to me that salt comes out of the ground, in this case in a salty stream that can then be evaporated to make such quantities of the stuff that you can drive a tractor into it to scoop it up. But it hadn't, until we visited Canyonlands National Park earlier this month.

From the Grand View overlook in the Island in the Sky precinct of the park, you can see some lacy pinnacles that the interpretive signage explains as 'salt fins' - these rocks were once surrounded and supported by massive salt deposits that have eroded away.

From Island in the Sky, we drove down the hair-raising Shafer Canyon Road, which switchbacks down nearly 3500 feet of narrow dirt road. (And when I say 'we', I mean 'he' ... because my contribution was principally taking some photos and, to a lesser degree, sweating and twitching.)

The photo at left, from half way down, makes it look grand, rolling, and picturesque, so I do want to emphasise that some parts of the road have a 2000-foot drop-off. Squeak!

As the saying goes, to call it 'steep' is to lose an unparalleled chance to use the word 'precipitous' ... but it is as lovely as it is rugged, and the sensation is of dropping out of the world into an endless solitude of eroding sandstone and rolling
sagebrush washes.

The road out to Moab broadly follows the Colorado River, through country that feels beautifully isolated and would be a poor place to be stranded without water. Here, upstream of the Grand Canyon, the river is still comparatively small. The road follows a ledge, still quite high above it, for twenty miles, not dipping down to river level until after the Potash mine.

There are washes leading down to the river, that must be waterfalls in their due season where they have not yet cut the harder layers of rock. Rock climbers could probably belay themselves down? John Wesley Powell, that one-armed climber of the Grand Canyon and other places, would presumably laugh as he went.

The first glimpse of the mine works is of one of the ponds, impossibly blue against the red cliffs behind. You round a corner and there it is, making the sky look pale, like a mirage of water in a thirsty place. That blue is doubly illusory - you can't touch it (it's behind a fence), let alone drink it, and it's dyed to speed evaporation.

Then we follow a network of dirt roads lined with corrugated sheds, chain-link fencing, 'no trespassing' signs, low power lines, and various impedimenta of heavy industry.

A stream crossed the road, and its banks were thick and white with salt. As many million tons of the stuff as have dissolved and passed down to the sea, there are still many more in the ground. The mining company used to have a staffed underground operation. After a terrible accident here back in the day, where 18 people were killed, since the 1960s they instead pump water down thousands of feet underground, whence it wells up, laden with salt and potash, to the evaporation ponds.

The sun was dipping low as we came around past the stream of salt water, to evening light reflected in the terraced ponds. In one, you could see tyre marks where some heavy-treaded vehicle had been driven into the brine itself to harvest the white crystals.

It was a tranquil scene, a quiet phase in a bewildering rollercoaster of activity precipitated by our need for this substance. Salt is, of course, not only or mainly for the table or even for the road. And this stuff is definitely industrial salt, made into ... things ... electrolysed into chloride for a thrilling variety of agrichemicals ... in everything from dish soap to paper to PVC piping. I thought it would be cool to think about where salt comes from and what it's used in. But there are simply so many uses for it, it is nearly as hard to keep in mind as air.

In conclusion, on my holidays I learned that it is a strange and wonderful, and salty, world we live in.