Cape Cod’s Center for Coastal Studies Geologist Mark Borrelli explains to interviewer Tim Wood the story behind the refuge bluff layers. The lower layer was fine sand, indicating that a river that once flowed here, when the eastern edge of Cape Cod was miles from where it is now. Above that layer was a layer of stones and rocks, indicating that the river had much stronger currents in a later period. The layer they were looking at was about 40,000 years old. Not something you see every day unless you hang out with geologists who can share something so remarkable.