On a recent cool, cloudy morning on the Millstone Hill trails in Barre, a couple of dozen people gather around our history hike leader, Scott McLaughlin. We are standing, he tells us, on the Barre Pluton, an “igneous intrusion” from the Devonian era (380 million years ago, give or take) that is four miles long, two miles wide, and ten miles deep. That bedrock of Barre Gray, the premier sculpture-and-monument-grade granite in the world, is the reason for Barre’s existence as we know it today. McLaughlin, who holds a doctorate in archaeology from Binghamton University (SUNY), is the executive director