The Acadian Orogeny is described by geologists as a collision of the African Continent with the North American Continent occurring many thousands of years ago. The event buckled the earths mantle and created a mountainous range as high as the highest found in the world today. Volcanoes spewed forth hot rock which cooled and compacted into a rock known as gneiss, a malleable, coarse-grained rock. The retreating glaciers ground down the mountains and melting waters worked out the valleys and intervales. Of such are the hills and valleys surrounding the Swift River Valley today, the beginning eastern edge of the Berkshires and north and south of this for many miles.

Gneiss rock split in two