Madison Boulder
Granite Glacial Erratic Roughly 83 Feet Long And 23 Feet High (Confirm), Described As One Of The Largest Known Glacial Erratics In North America (Confirm), Protected As A Small State Natural Area And Designated A National Natural Landmark. · Madison, New Hampshire
A single enormous block of granite sitting in the woods of Madison, about 10 minutes south of Conway, and one of the largest known glacial erratics in North America (confirm). The boulder is commonly given as roughly 83 feet long, 37 feet wide and 23 feet high above the ground, with more buried below, and is estimated at several thousand tons (confirm). It was plucked from a granite ledge a short distance to the northwest by the Laurentide ice sheet, which covered New England until roughly 12,000 to 15,000 years ago, and dropped here as the ice melted. The site is a small state natural area and a National Natural Landmark, reached by a dirt road and a walk of a few minutes from a small lot. There is no visitor center, no fee and few if any facilities (confirm). Most people spend 20 to 30 minutes walking around it, touching the cold rock and trying to fit it in a photo, and pair it with a drive on the Kancamagus Highway, a hike on Mount Chocorua or a day in North Conway.
Madison Boulder Road (off NH Route 113), Madison, New Hampshire, 03849, United States
The natural area is open all year from dawn to dusk with no staff, gate or fee. The dirt access road is best from late spring to late autumn; it is often unplowed or poorly maintained in winter, and the small lot may be buried in snow, so a winter visit may mean parking by NH Route 113 where legal and walking in (confirm). Mud season, roughly April into early May, can leave the road rutted and soft. There are no buildings to close; restrooms, if any, are basic and seasonal (confirm). Leaf cover from June to September hides the boulder until you are close, and late autumn and early spring give the clearest view of its size through bare trees.