The deepest stratified dig of its kind in Pennsylvania (USA) has now been completed after three years of work by archaeologists, geologists, botanists, geophysicists and volunteers. The site, a section of Leetsdale Industrial Park, was formerly a sandbar, and then an island, in the Ohio River before attaching itself to the mainland. It has never been ploughed or otherwise disturbed, allowing archaeologists to locate perfectly segmented layers that have been sealed by sediments deposited by periodic flooding.
     The dig ranges from 16ft to 18ft in depth. Portions of the excavation have revealed evidence of activity from Archaic periods (6,000 BCE to 1,100 BCE) and the Early Woodland period (1,100 BCE to 200 CE). The separated layers show where the occupants moved from hunter gathering to settled agriculture. Artifacts include chippage from the production of stone arrowheads and spearheads, stone tools, and a 3,000 year old sandstone bowl weighing 8 lbs. Archaeologists also found steatite (soapstone) discs, uncharacteristic of southwestern Pennsylvania but common in southeastern Pennsylvania and Maryland. Soapstone was used for making bowls and the discs may indicate that the inhabitants migrated from the eastern part of the State.
     The state museum commission will be responsible for long-term documentation of the artifacts. Exact time periods will be determined by analysis of soil samples, including red and oxidised soils that provide evidence of shallow fire pits. At the same time researchers will provide a unique picture of climate change over the period of occupation, down to the present day.
     The site was discovered by an archaeological survey undertaken prior to the replacement of the Braddock Dam, which was due to begin in 1999. Construction planning was refined to allow the excavations, which began in 2000. The site will now be back filled and returned to the industrial park at the end of July 2003.

Source: post-gazette.com (4 June 2003)