European settlers deforested the land to create farmland. This exposed the soil to intense freeze-thaw cycles, which caused buried stones to "heave" to the surface, creating what farmers called a "second crop" of rocks.
Glaciers deposited uncrushed rock across the region, leaving behind a "glacial till" of stones, boulders, and gravel. Stone Walls
The prevalence of stone walls resulted from a unique combination of natural and human processes: European settlers deforested the land to create farmland
Most walls were built between 1775 and 1825, often called the "frenzy" of wall building, reflecting a period of intense agriculture. Cultural and Environmental Significance Stone Walls