there were places south of the expanding glaciers where groups of people could break off from the coastal route and go inland along rivers and streams. The southern edge of the glaciers was just slightly below where the US-Canadian border is today, running east/west in an uneven line.
Just a few miles south of the glacier much of the land was marshy from glacial runoff water and ponds and had wild grasses growing. Animals were attracted to the area which brought people following them. So some of the oldest evidence in North America of human occupation exists in areas along the ancient glacial line across the continent.
One such site is the Meadowcroft Rockshelter in PA just west of Pittsburgh. It was excavated by Dr. James Adovasio starting in the 1970s and continuing into the 1990s. Evidence indicates that the rockshelter had continuous use by people from 19,000 years ago up to the time of the American Revolution. Dr. Adovasio was at the University of Pittsburgh at the time. He left there to found an Archeological Institute at Mercyhurst, a private Catholic university in Erie, PA.
Erie is my home town, but I now live in western NY. When deciding where to go to finish a degree that I had started when I was younger, I visited the Mercyhurst admissions office. Since I wanted a language major and anthropology minor, they introduced me to Dr. Adovasio's staff when they took me on a campus tour. On subsequent visits, I was able to spend time talking to his staff about the first people in the Americas and how they arrived. Later that summer I volunteered on a local dig that the archaeology students did for field experience. No big discoveries at that site, but I had a chance to talk with people again about various sites and dates. It was the Mercyhurst archeology staff who introduced me to the idea of a water route into the Americas.
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