Glenn Kreisberg is a researcher, engineer, author of Spirits in Stone: The Secrets of Megalithic America and co-founder of The Overlook Mountain Center in Woodstock, New York. For this in-the-field episode, we visit a mysterious archaeological site, a mountainside covered in signs of ancient indigenous habitation, enigmatic cairns and serpentine walls. After a reading of early 19th-century accounts from the likes of Lewis & Clark about stone heaps and large stone worship in Native America...