Slicing through the clear desert air, pilot Harry Casey advises his passenger to take a look at the ''beautiful'' sight on the desert floor. But all the untrained observer sees is a mass of parched land and jagged peaks pitted by deep arroyos, scrub brush, and the twin tire signatures of off-road vehicles.
''Take another look,'' says Mr. Casey, pointing to the obvious with his right wing tip and swooping lower. Emblazoned on the earth are two giant stick figures - communications from an ancient Indian culture that once thrived in this arid setting.
It is a startling sight to come across in this barren expanse. The desert gives up little - least of all its secrets. And these ''geoglyphs'' - religious messages that have long outlived their creators - have remained a secret for thousands of years.
But now, having survived time and weather, the ''geoglyphs,'' say the few archaeologists who know about them, may be endangered by man's curiosity and ever-encroaching development, by housing and off-road vehicles. From a bird's-eye view, pilot/photographer Harry Casey compiles a pictorial record of the Southwest's geoglyphs. About 250 of the figures - many several hundred feet long and up to 8,000 years old - have been discovered so far.
A handful of people have embarked on a massive effort to find, document, and protect the ancient etchings scattered in the Southwestern desert from Death Valley and the Mojave Desert in California to the fork of the Arizona-Nevada borders and south along the Colorado River into Mexico.
While no one is sure exactly what the figures and patterns in the earth mean, the important thing is to save them first and ask questions later, says Jay von Werlhof, an instructor at Imperial Valley College.
What is known right now, he says, is that geoglyphs, earlier known as ''intaglios,'' include figures ranging in size from a few feet to several hundred feet. Some were scraped by hand on the desert ''pavement'' - others were formed by rock alignments or dance patterns stamped into the desert floor. Rock alignments and geometric patterns are believed to be as old as 8,000 years, he says, while other primitive stick figures of men and animals could have been done as recently as 100-500 years ago.
This theory is supported by Boma Johnson, an archaeologist with the Bureau of Land Management in Yuma, Ariz., who marvels that he had never even heard of a ''geoglyph'' or ''intaglio'' when he came out of graduate school.
''Most archaeologists in Arizona have been oblivious (to the figures). . . . When you boil it down, between us (himself, von Werlhof, and Casey) we're probably about (the only experts),'' says Mr. Johnson. (However, Mr. von Werlhof gives credit to archaeologists Emma Lou Davis, of the University of California at San Diego, and Arda Haenzel from San Bernardino, Calif., for the earliest research on the geoglyphs, in the 1950s.)
Those few who do know about the geoglyphs are an avid bunch. Von Werlhof says one couple has enrolled in his classes for 18 semesters. He says his archaeology classes include the most active field program in the country, and have surveyed 60 to 70 percent of the Connecticut-size Imperial County during the last nine years.
Harry Casey, an Imperial Valley farmer by trade, was snared by one of von Werlhof's classes four years ago. Ever since has been devoting large amounts of time and money searching for and documenting the geoglyphs. Using the Piper Cub he parks next to his house, Casey has been responsible for finding and photographing - by leaning out the window of his low-flying plane - many of the 250 geoglyphs now recorded in the Southwest, von Werlhof says. By contrast, he adds, only a half dozen of the geoglyphs had been found from the 1950s to the ' 70s, when his research began.
Unrecognizable from the ground (unless you are one of the few experts who can find them on foot), the geoglyphs had been unknown even to locals like Mr. Casey , who grew up in the Imperial Valley and had never seen one until taking the class. And while experts want to share the marvel of this ancient art, they are very protective of it.
Von Werlhof and Johnson explain that too much attention could backfire.
Putting up fences ''says there's something there worth looking at,'' says von Werlhof. ''Many (geoglyphs) can best be protected by saying nothing about them, '' he adds, noting that geoglyphs can be damaged or destroyed as easily from unintentional acts as deliberate ones. Drivers of dune buggies or motorcycles can plow right across one of the Indians' sacred geoglyphs and not even know it. Further, von Werlhof says, ''some people don't realize that by letting kids scuff their feet across it (a geoglyph), it is being destroyed.''
Ironically, he says, the first known concern for the safety of the geoglyphs came after a 1950s National Geographic pictorial drew attention to them.
While not even the descendants of the desert Indians are certain what message the geoglyphs were conveying, it is generally accepted that they are a form of prayer for such tribes as the Mojave, Quechan, and Yuha. Indians here still consider the sites sacred. Many are pleadings with their gods at times of crisis , it is believed. Thousands of years ago, von Werlhof speculates, the request may have been for water and the return of the lush lakelands that the area had during the Ice Age. Later, as the white man began to encroach on Indian lands, the prayers dealt with creation myths which would reinforce Indians' identity with their homeland.
Mr. Johnson is currently recruiting federal funds and volunteer support to fence off geoglyphs. About a dozen have been fenced, he says, and a dozen more that appear to be endangered have been selected for fencing. Also, fencing is planned along highways to discourage off-road driving near 25 or 30 other figures. Further, off-road-vehicle associations and land developers generally support protective efforts, Johnson says. He speculates that potential backlash from environmentalists over destruction of the geoglyphs is a strong motivation for this.
Von Werlhof has focused his efforts on documentation of sites. He estimates that he and Casey have documented, by land and air, about 90 percent of the Southwestern geoglyphs. The University of California at Los Angeles will publish his findings in three volumes beginning this summer. Von Werlhof says that his book is for the scientific community ''rather than the general public.''
The protective attitude, says Mr. Johnson, is important because while relics of the same era from other parts of the world can be lifted and put in a museum, the geoglyphs are a part of the earth. ''Most of these are very fragile and the situation is just about as bad as if you had a Picasso hanging out there (unprotected) in the desert.''
Dipping his plane over one human stick figure north of Blythe, Calif., Mr. Casey points out that the head has been obliterated by what appear to be the tracks of a World War II-era tank (Gen. George Patton used the area for tank and shelling practice). Mr. Casey shakes his head and notes that just as he is looking at the fading geoglyphs of an ancient time, people a thousand years from now are likely to see tire tracks as a testament of the 20th century.
If delicate geoglyphs have been there this long, he reasons, one wild skid with an off-road vehicle ''will leave a mark for thousands of years.''