In a corner of the SugarHouse Casino property on Delaware Avenue, archaeologists hit a mother lode of Native American artifacts.
From a plot about the size of a public pool, crews unearthed 182 items in only a foot or so of soil. Some date back 5,000 years, making this the largest single discovery of prehistoric items in the city, local archaeologists say.
So significant is the find that experts for federal and state agencies have urged deeper excavation of the site.
But what other treasures lie hidden there will not be revealed anytime soon.
SugarHouse has changed its design plan. One consequence is that the area where the Indian relics were discovered will be paved for a parking lot, said Leigh Whitaker, a spokeswoman for the project.
The developer also will postpone excavating under Penn Street for evidence of a Revolutionary-era British fort and investigating seven shafts that could be colonial privies.
"It's our intention at some point to complete that work," Whitaker said. "We just don't know when."
SugarHouse is free to curtail archaeological work because it no longer needs a federal permit from the Army Corps of Engineers in order to build a slots parlor on 22 acres in Northern Liberties and Fishtown.
The partners produced a new design eliminating a promenade that would have hung over the river - and required the permit.
With the previous design, they had to conduct a historic review of the site to get the permit. As part of that process, they hired archaeologists in 2007 to dig up parts of the tract.
More recently, the project manager and the Army Corps were working on an agreement on how the work should proceed, with input from the Pennsylvania Historical and Museum Commission.
Now, with the design change, that process will stop.
Any previous understanding "would not be legally binding," said Ed Voigt, a spokesman for the Army Corps, which regulates waterways.
Mark Shaffer, a historic-preservation specialist for the state museum commission, said SugarHouse should follow through with the work "before those resources are adversely affected by the project."
Whitaker said SugarHouse planned to continue working with the state commission on the most significant portions of the site. The area where the Indian artifacts were found - and where the parking lot will be - is eligible for the National Register of Historic Places. Among the items were an arrowhead, a drill, and flakes from stones used to make tools.
For the moment, the relics belong to SugarHouse, which is storing them in a climate-controlled space.
"At some point, we'll turn them over to the museum commission," Whitaker said. "We don't have any use for artifacts in a casino."