Mysteries of the mesa solved

MESA VERDE NATIONAL PARK, Colo. — Almost a century after these ancient Indian ruins became a national park in 1906, strange earthen formations near the cliff and mesa-top dwellings continued to puzzle and divide scientists, until recently.

One mysterious dirt mound, 200 feet across, rises 16 feet above the floor of Morefield Canyon. A 1,400-foot path or channel extends from it, making it resemble an upside-down frying pan with a long, flat handle.

And then there was the large depression in the park's heart on Chapin Mesa. It was labeled for years as either a prehistoric amphitheater or perhaps an impoundment of water — nicknamed Mummy Lake — with no known source of water.

Now, scientists know the depression was part of an elaborate water storage system and have dubbed it Far View Reservoir. And Morefield Canyon's elevated mound, which does not resemble a reservoir, was a storage facility that could have held 120,000 gallons of water.

After a decade of investigation just ended by a large team of private water engineers and government scientists, it is recognized that the Ancestral Puebloans who lived here until 1300 were remarkable water engineers.

"They knew how to manage water," says Eric Bikis of Wright Water Engineers Inc. in Durango. "They were ingen- ious."

The people of this high desert, without benefit of metals, wheels or written language, maintained at least four massive waterworks from A.D. 750 to 1180 to survive the devastating droughts of the Four Corners region. The last of these works studied, a large mound dubbed Box Elder Reservoir, wasn't discovered until a 2002 wildfire burned off a dense, high carpet of sagebrush.

But scientists had been confused for decades over how the giant mud pie in Morefield Canyon, high above the bed of a desert stream that rarely flows, could have served as a reservoir. Many guessed it was a terrace for ceremonial dances.

In the late 1990s, Denver water engineer and author Kenneth Wright, known for his studies on ancient Incan waterworks in the Peruvian Andes, collaborated with engineers and government researchers to cut a deep trench through the Mesa Verde mound and finally solve the mystery.

The Puebloans, the team concluded, had started with a shallow depression that was originally along the bottom of an intermittent stream. They used the small impoundment, and others such as Far View, to capture water during rare big storms, which occur several years apart, Bikis says.