A thousand years ago, Native Americans aligned drawings with solstice sun
Hundreds of years ago, Native Americans in what is now West Texas drew more than a thousand glyphs in red pigment on rocks on a cliff. Every winter solstice at noon, the sun strikes the center of one of these figures. One might conclude the person waited until sunrays alighted on the rock at noon, marked the spot and then drew the figure around it. But how did the person know it was 12 p.m.?
The Houston Chronicle online had another question: “Among the mysteries of how ancient people created structures to mark the solstice and equinox with astonishing accuracy, this one is central: How did they determine the dates of those astronomical events?”
Gordon Houston is a doctoral candidate specializing in this very riddle. He thinks he knows the answer for what are called the Pictographs of Paint Rock, Texas, which are drawn on limestone cliffs on a ranch in Concho County. There are about 1,500 of these drawings, about a dozen of which "had a solar interaction," Houston told Chron.com.
Chron.com describes the remarkable event: “Perhaps the most striking of these dozen pictographs is a red circular design painted on the cliff about 20 feet above the ground. At exactly noon on the day of the winter solstice -- the shortest day of the year and the traditional beginning of the winter season -- there's a dagger of light hitting the exact center of the glyph as the sun shines through spaces between layers of broken limestone.”
The accuracy of astronomical calculation exceeds that of Stonehenge in England, Houston said. He has a master’s degree in astronomy and is director of Blinn College’s Schaefer Observatory.
Houston calls it incredible that the artist drew the glyph on the right day at the precise time, assuring it would be highlighted.
He has visited other ancient sites tied in with astronomy, including three on the Black Sea, Chaco Canyohn of New Mexico, Chankillo in the desert of Peru and Machu Picchu of Peru.
Dates given for the West Texas petroglyphs vary from 1,000 years ago per the Texas State Historical Association article to between 1300 and 1700 A.D., an estimate given by Houston. He said the area was a site frequented by nomads and used by different groups over time.
The historical association describes the rock art:
There are an estimated 1,500 paintings spread out over a distance of one-half mile. The site is on private land owned by Kay Campbell. The range of time covered by the pictographs is fairly long, extending from the dim prehistoric to the early historic period. Dating the pictographs precisely has not been possible. Several artifacts and prehistoric features have been found, however, in association with them that help in establishing a rough date. Sherds of Leon Plain ceramics and burned rock middens suggest a date of 1,000 years before the present. No evidence has been found that would suggest an earlier date.
The glyphs are of animals, humans and geometric figures and hand prints in yellow, orange, red, white and black. The colors were derived from oxides of iron. The black is carbon and the white is chalk.
Pictograph of Spring sky shows movement of star groups & predicts spring equinox, near Paint Rock.
Kay Campbell and her husband, Fred, began to notice the sun striking the glyphs at astronomical moments in the late 1980s. A 2002 paper by Fred Campbell and William P. Yeates that explains the story is online. In December 1996 she saw light striking the center of the red glyph and the astronomical significance dawned on her.
For 18 years thousands of people have gone to observe the amazing light interactions with the glyphs, Chron.com said.
Houston, 61, believes he is the first person to determine how the glyphs’ creators calculated the solstice date accurately. He made many visits there and climbed the cliff to attempt to nail down the artists’ observation post.
'They were expert watchers of the sun along the horizon," he told Chron.com. "Determining the point of observation is critical in any ancient astronomy site.'
Houston, age 61, is a student in archaeoastronomy at Ilia State University in Tblisi, Georgia.
He will give a talk about his research at the Houston Archeological Society's February 12 meeting at the University of St. Thomas. He will discuss his findings and reveal why he believes the artist’s observation point was a notch in the cliff that intersects a relatively featureless horizon. Members of the public may attend his talk for free.