Roosevelt Lake in east central Arizona provides most of the drinking water for the three million residents of metro Phoenix. Because of the extended drought in the southwest, the lake is two thirds empty. That's bad for people depending on the water, but archaeologists have hit the jackpot.
Roosevelt Lake is buried deep in a rocky, dusty basin of the Tonto National Forest about 100 kilometers northeast of Phoenix. It's not easy to get to, even in a four-wheel-drive truck. But for scientists eager to study past cultures, it's well worth the effort.
"And here we have some early decorated pottery, nice red on buff. Early Hohokam stuff," says archaeologist Scott Wood as he fiddles with a fragment of pottery from a 1,300-year-old Indian village. It's dusky red with black, jagged lines painted across it. Mr. Wood, who wears a cowboy hat, has a salt and pepper ponytail and chomps a cigar, is fascinated with this site, and the remnants of the Hohokam Indians. The tribe started migrating here from Mexico more than 2,000 years ago. They are especially well known for their handiwork with tools. "What we have here is what we call hammerstone. The primordial human tool," he explains. "You use a hammerstone to flake rock off of other rocks to make, you know, arrowheads and knives and stuff like that. So this is sort of the basic tool that leads to everything else in the prehistoric technology out here."
A hundred years ago, before the Salt River was dammed to create Roosevelt Lake, water flowed through a narrow channel. Now, a light blue lake with 180 kilometers of shoreline stretches out beneath tan and gold hills. Over just the last few years of drought, as the lake receded from its high water shoreline, it has slowly revealed this wonderfully preserved Hohokam Indian village, known as Armor Ranch. It's one of the most extensive archaeological sites in the Southwest, a settlement where tens of thousands of Indians lived along the terraced, red and off-white river banks.
Steve Germick, the Forest Service archaeologist in charge of the site, says there is no end to the treasures here. They go layers and layers deep. "There are probably hundreds of structures and features buried out here that we just cannot see because of the long-term occupation and the superimpositioning of structures and features," he says. "You have the siltation [covering of lake sediment], the vegetation cover, and you've got an occupation of 500-700 years here. People were here for a long time."
But even the rough remains left bare by the water reveal much about the area's former residents: remnants of huge rock fortresses arranged in large ovals, built for defense, are visible in the dirt. The Hohokam were highly social, too. Rock walls were linked together to make stone compounds complete with interior hallways, cooking pits, and rooms. Scott Wood says, by the looks of it, this was a bustling, highly-advanced village. "When this site was occupied, this would have been the center for everything going on in Tonto basin," he says. "It was the biggest, the best. It sits on some of the best farmland in the basin."
There are clusters of rock structures spread across several square kilometers, many of them hiding in bone-dry cocklebur bushes.
Steve Germick has just stumbled on another rock formation he suspects was built by the Hohokam. He wants to generate maps of the area that will help scientists understand the way some of the first inhabitants of the Southwest lived 1300 years ago.
There's no federal or state money dedicated to this research, so the excavation thus far has been left to a few dedicated people. Mr. Germick comes out here on company time when he can, and on weekends and holidays with other volunteers when he can't. The workers pore over each and every detail of the site, while dodging the occasional rattlesnake and the constant, unrelenting sun. The site has been studied for a decade, but with each year the drought continues, the lake recedes still further. It's 20 meters below capacity now, revealing more treasures than archaeologists could have dreamed of.
Jeff Clark, a preservation archaeologist for the Tucson-based non-profit Center for Desert Archaeology, says the fact that Armor Ranch lay submerged for so long helped protect it from looters and developers.
"There's so much vandalism going on," he points out. "There are so many sites that have been destroyed. There's very few communities where you have multiple sites, where you can look at the entire picture of settlement in an area and trace it back to its roots."
Mr. Clark calls Armor Ranch the 'heartland' for understanding the Hohokam and their journey to this part of Arizona and the Southwest, a migration which set the stage for Indian cultures that came later. For Steve Germick, the lonely archaeologist studying these treasures, the drought can't last long enough. "We've just scratched what's out here. Just scratched," he says.