South Mountain Loop

South Mountain in Pawtuckaway State Park is crowned by a historic fire tower offering panoramic views of southern New Hampshire's lake and hill landscape, but the mountain's most remarkable geological distinction is the presence of the largest field of glacial erratic boulders in New Hampshire — some of the most extraordinary in all of New England. The Pawtuckaway boulders were deposited by the Laurentide Ice Sheet during its final retreat approximately 12,000 years ago, when meltwater streams beneath the glacier carried enormous volumes of rock debris from the White Mountains 50 miles to the north and deposited them across the Pawtuckaway terrain. Individual boulders reach 20 to 30 feet in height and cluster in dense boulder fields that require creative route-finding. The granite composition of many boulders — clearly distinct from the local bedrock — provides direct evidence of their glacial transport. The loop trail circumnavigates South Mountain's rocky summit, passes through several dense boulder fields, and visits a series of glacially polished bedrock outcrops. The fire tower, restored and maintained by a local volunteer group, provides 360-degree views extending to the White Mountains on clear days. Pawtuckaway Lake is visible below, along with Pawtuckaway's distinctive ring dike geology — a rare circular intrusion of volcanic origin visible in aerial photography.