I have been asked, more than once: "Are you obsessed with the 'Spiral Jetty?' "

If so, I'm not alone.

This may be quibbling, but actually I see the lure of artist Robert Smithson's world-famous (if not Utah-famous) earthwork swirl of salt-sprayed basalt boulders in the northern reaches of the Great Salt Lake as more the photogenic subject of a "chronicling impulse" than an obsession.

How often is a lifelong, camera-toting journalist and wanderer presented an opportunity to witness hour-to-hour and season-to-season, let alone year-to-year, changes occurring so visibly at one geographic location?

And that at a spot selected by a (literally) groundbreaking artist for a one-of-a-kind artwork precisely for its natural characteristics — to purposely expose his creation to "entropy," the gradual alterations wrought by erosive time upon matter: say, a simple, 1,500-foot-long rock jetty coiling into a salty inland sea.

Smithson was a New Jersey-born, New York-based conceptual artist and intellectual fascinated (obsessed?) by entropy, by spirals — an ancient design with many meanings — and by the idea of large-scale "earth art" away from the confines of traditional museums and exhibit rooms. He also kept in mind what his outdoor artwork might look like from the air — which was the only way to really see it for many years.

In 1970 Smithson envisioned an "immobile cyclone" in the pink water tinted by algae and bacteria off the Great Salt Lake's Rozel Point. It would be an artifact of what he described as our "Carboniferous Period," marooned in a zone of "modern prehistory" along with nearby castoff industrial debris.

Smithson outlined his jetty with poles and string in the then shallow water; hired a couple of dump trucks, an earthmover, a tractor and a perplexed crew; and built the "Spiral Jetty" with black boulders and earth from the site, leased from the state of Utah.

Tragically, he died three years later at age 35 in a plane crash while surveying another of his remote projects, "Amarillo Ramp," in Texas.

His notebooks are filled with fanciful sketches and diagrams. He wrote an essay about his jetty project and filmed the work as it was being done. He called all — the earthwork, the essay and the film — "Spiral Jetty," or "The Spiral Jetty."

Almost two dozen times in the film's narration, conjuring the view in every direction from the jetty's center, he intones:

"Mud, salt crystals, rocks, water."

The mantra is also found in Smithson's writings.

Thirty-five years later, New York Times critic Michael Kimmelman called Smithson's multimedia vision "cunning and prescient."