The white-colored outlines of rectangular shapes could very well be the markings of a construction site, albeit one that was undertaken more than 700 years ago.
“You see the artifacts on the surface, that lets us know we have a site,” said Debbie Swartz, an archaeologist with Desert Archaeology.
Those outlines mark the walls of a Hohokam pit house, part of an ancient city that was uncovered by archaeologists in mid-April at the site of a major road and park project in Marana.
The main find is at the future site of the Cortaro-Silverbell District Park. Due to the discovery, park construction has halted to allow archaeologists more time to study the area. Nearby road construction remains on schedule.
A large, 18-inch thick adobe wall was discovered in the area, along with a host of pit houses and ancient Hohokam artifacts.
Several pit houses were also uncovered at the southeast corner of Ina and Silverbell roads.
Dwellings and artifacts were not the only things unearthed at the site.
“It is a sensitive subject to the tribe, but we can say from what we’re finding that there must have been a very large population here,” said Marana Cultural Resources Manager Su Benaron. “It would’ve been a large village, probably one of the major population centers at the time it was occupied.”
Members of Desert Archaeology are carefully complying with an agreement with the Tohono O’odham to repatriate the remains with the tribe.
The site had other surprises in store.
“One of the other interesting things is we’ve found several burials of dogs, so dogs seem to be specially treated as well as people,” Beneron said.
Doing an archaeological dig on a construction site involves give and take between the dozen or so archaeologists working on the project and the workers from Granite Construction charged with building the road.
“The challenge is how do we do all that and that has been the tightrope we walk,” said Marana Public Works Director Barbara Johnson.
The Silverbell Road widening project will expand the road to four lanes between Cortaro and Ina roads, plus a turning lane.
Due to delays, both excavation and non-excavation related, the road project has seen its deadline pushed back about three weeks, but is still on target for a November opening, said Marana Construction Inspector Mac Murray.
The town and Granite Construction were able to work around the excavation, giving the archaeologists as much time as they need. Before park construction can resume, a method must be drawn up to appropriately preserve the area.
“When the preservation plan is approved, then we can determine the next step,” Murray said.
In two to three weeks, the plan will be submitted to the state’s historic preservation department and the Army Corps of Engineers concerning direction on how to care for the site, Benaron said.
This particular settlement was inhabited primarily because it was close to the Santa Cruz River. Other Hohokam settlements are nearby, notably in North Marana and the Continental Ranch area.
The Hohokam lived in central and southern Arizona from about 300 B.C. to 1450 A.D., at which point they mysteriously disappeared. The most visible reminder of the Hohokam is likely the four-story remnants at the Casa Grande Ruins National Monument, about 50 miles northwest of the settlements along Silverbell Road.
Tens of thousands of artifacts, including pottery shards, arrowheads, burnt matter, shells and bone tools, have been uncovered from the site. After Desert Archaeology analyzes them, most of the findings will be donated to the Arizona State Museum.
“What you’re seeing here is the tip of the iceberg,” Swartz said. “For every day we’re in the field, we spend about three hours in the office.”
Finding the objects themselves is only half of the archaeological equation.
“There are a lot of specialists that take a look at the materials. They take samples of the soil that are looked at for microscopic bits of pollen to see what the plants were like. They take samples for carbon 14 dating,” Swartz said.
Different types of analysis help corroborate a time period of when the site was in use. Using patterns found on pots, experts can tell when or where a vessel came from.
Archaeomagnetic dating measures the earth’s shifting magnetic north to further ascertain dates. For example, two vessels uncovered are significant because they push the end date of the village back to about 1350, much later than previously thought.
“Everything gets looked at very carefully and helps us put together a story that approximates as best we can the way people lived,” Benaron said.
Much like the Vista del Rio site near Tanque Verde and Dos Hombres roads, a portion of the site will be adapted into an interpretive area of the park, where visitors can wander the area looking at, but not keeping, small artifacts that have worked their way to the surface.
“In our park site, we want to put exhibits trails, signs and replicas and do various things to present what we know about the past, what we’ve learned about this excavation to the public,” Benaron said.
Today, it is standard procedure to do an archaeological survey of an area before any construction projects begin. This was not always true, especially when Silverbell Road was originally constructed.
“It was build a long time ago and the laws have gotten a lot stricter for archeology in the last, say 25 years,” Swartz said. “While they did know where sites were and sometimes there would be some recording done in the ‘70s and ‘80s, but they didn’t have the laws and ordinances to back up doing the work the way they do now.”