Major archaeology sites protected at U.S. Army Yuma Proving Ground

As a military installation, U.S. Army Yuma Proving Ground has a proud history dating back to the 1940s.

Part of Gen. George S. Patton's Desert Training Center/California-Arizona Maneuver Area during World War II, 20 divisions of men trained here for combat, and ten of these liberated Nazi concentration camps in Europe.

From the 1950s forward, the proving ground has tested virtually every piece of equipment in the ground combat arsenal for the most impressive military in world history. Technologies like the global positioning satellite (GPS) system were pioneered here, and today cutting edge commodities like unmanned aerial systems are put through their paces prior to being fielded to troops.

But the installation larger than the state of Rhode Island is also home to history that is far more ancient. A crossroads for native people for at least 7,000 years, there are hundreds of culturally significant sites within the modern boundaries of YPG. The stewardship of these irreplaceable sites is a high YPG priority, with the proving ground performing painstaking ground surveys of between 12,000 and 15,000 acres annually.

Some of the sites are isolated: vestigial remnants of ancient trails with the occasional arrowhead or potshard strewn on the ground. Others are awe inducing: White Tanks is a canyon studded with natural rock cisterns that retain rainwater year-round. Some crevices within this undulating volcanic rock have impressive stone formations rising from the center of the ponds.

"It's important spiritually to Native American tribes of this area," said Dr. Meg McDonald, YPG archaeologist. "It's also very important in an archaeological sense because there's a large concentration of camp sites, trails, and petroglyphs."

In fact, a survey done of the vicinity in the early 1990s found more than 46 archaeological sites in the area, one of which includes hundreds of petroglyphs.

"It was an important site because it is a water source," said McDonald. "It is also one of several obsidian sources in Arizona, which was used for smaller arrow points."

The water itself may not be palatable by modern civilization's standards: it is still and brackish, sporting a thin, but noticeable film of algae across the top. Bees hover near the water, their low drone one of the most audible sounds in the silent canyon. But to a parched desert traveler of hunter-gatherer times the water was life-saving. Across the millennia, passers-through decorated the canyon walls with hundreds of intricate petroglyphs that remain to this day, a faded but stirring testimony to the importance of this natural wonder to unknown numbers of travelers.

"This is one of the most significant archaeological sites in Arizona," said Andy Laurenzi, southwest field representative of Archaeology Southwest, a non-profit organization dedicated to exploring and protecting the places of the past throughout the American Southwest. "You have this relatively undisturbed landscape with quite a concentration of petroglyphs and indications of human occupation for thousands of years. You find similar places along major river systems, but not very often in arid parts. The added significance of the area is its association with Malcolm Rogers, one of the pioneering archaeologists in the Southwest. Remnants of his camps in the White Tanks are present today."

Along the top of the canyon are small caves, some of which have ancient pot sherds and other artifacts, all suggesting human habitation.

"People were living here," said Laurenzi. "Maybe not year-round, but certainly for sizable periods of time. If you're going to go to the trouble of carrying in pottery, it suggests you have plans to stay awhile."

Despite the fact that trespassing on military land is both unsafe and a violation of federal law, people still occasionally slip in to White Tanks and other cultural sites intending to loot or vandalize. Though site surveys over the past two decades show the site is relatively unchanged, YPG personnel want to be proactive in preserving the site for generations to come. In addition to upgrading gates, the likeliest long-term solution is a site stewardship program comprised of YPG employees willing to volunteer their weekend time for periodic site inspections.

"Part of our job is advocating for the preservation of cultural resources," said Laurenzi. "The military has done a great job of stewardship here by recognizing the importance of White Tanks and other sites like it. The designation of White Tanks Management area by YPG helps minimize intrusions, and that's good news."