Archaeologists ponder whether cliff dwellers were geometry users

MESA VERDE NATIONAL PARK, Colo.—Seen from the air, the structure is a D-shape, perched on the lip of a mesa that overlooks the famous

“Cliff Palace” dwelling at Mesa Verde National Park. Scientists call it the Sun Temple.

But what is it? An 800-yearold observatory? A ceremonial structure? A mix of both?

“There are a lot of theories out there, but really, people don’t know,” said Tim Hovezak, an archaeologist at Mesa Verde National Park. The only people who would know are the Ancestral Puebloans—also known as the Anasazi—who built structures across the Southwest and then started abandoning them in the 13th century.

Mesa Verde is filled with mysteries. Over the last few years, research on the Sun Temple has added to them.

In a recent paper, an Arizona State University mathematician examined aerial imagery and concluded that the Sun Temple contains sophisticated geometric patterns, including Pythagorean triangles and other shapes used by other ancient civilizations. The mathematician, Sherry Towers, also concluded the Sun Temple’s builders had used a common unit of measurement—roughly 30 centimeters—in designing the site.

“These findings represent the first potential quantitative evidence of knowledge of advanced geometrical constructs in a prehistoric North American society,” Towers wrote in her paper, published in the April edition of the Journal of Archaeological Science Reports. This knowledge is “particularly remarkable,” she

added, “given that the ancestral Pueblo peoples had no written language or number system.”

Towers’ conclusions are not universally accepted. Hovezak says it is too early to know whether the Anasazi intentionally incorporated sophisticated geometry into the Sun Temple design. Towers agrees, but as she noted in her paper, “The relationship of those geometric constructs to the apparent common unit of measurement at the site is extraordinarily unlikely to occur by mere random chance.”

The forerunners of the modern Pueblo people, the Anasazi are known for their remarkable cliff dwellings and structures such as Pueblo Bonito at Chaco Canyon National Historical Park in New Mexico. They built many of their communities in the 1100s, in what is now known as the Four Corners region, where the boundaries of Arizona, Utah, Colorado and New Mexico meet. Based on what they left behind—including irrigation systems essential for growing maize, a main food source—the Anasazi must have been impressive masons and engineers.

Two centuries later, the Anasazi started abandoning their villages. For decades, researchers debated the possible reasons. Then archaeologists working in the Dolores River Valley of Colorado during the 1980s unearthed convincing evidence that climate changes had caused this ancient civilization to fall.

As archaeologist Kenneth Lee Petersen wrote in 1989: “The findings from this project indicate that it was not simply a drought that forced the Anasazi to leave, but an extended drought coupled with changing weather patterns and a colder climate. This long-term change in traditional weather patterns made dry-farming—the source of a majority of Anasazi food— virtually impossible.”

Scientists have theorized that the Anasazi started occupying the Cliff Palace in the mid-1000s, then built the Sun Temple sometime later. Originally, the D-shaped structure may have had walls 11 feet high, with four circular towers—or kivas—rising from the site.

Towers, the Arizona State University mathematician, originally became interested in the Sun Temple because of the possibility that it served as an astronomical observatory. “When I saw that the layout of the site’s key features also involved many geometric shapes, I decided to take a closer look,” she said in a statement from ASU.

Analyzing aerial photography, Towers found that the interior of the Sun Temple was laid out with some precise geometric shapes, including “golden rectangles.” Golden rectangles have a precise ratio between their longer and shorter sides and were incorporated into architecture by many ancient civilizations, including Greeks, who considered them to be visually pleasing.

In her research paper, Towers said it was unclear why “these ancients potentially felt the need to employ these constructs in the Sun Temple site.” She added that further study is needed to see whether such shapes were used at other Anasazi sites.

Hovezak, who has been working at Mesa Verde for 12 years, said Towers’ research had helped firm up the evidence that the Ancestral Puebloans had used some kind of system of measurement in their constructions. In Mesa Verde alone, there are over 600 cliff dwellings, with hundreds of others—some barely studied or preserved—scattered across the Southwest.

“I find Towers’ research fascinating,” said Hovezak. “I am not entirely sold on it, but it is intriguing.”