| Madison Boulder Natural Area | |
|---|---|
 The Madison Boulder as photographed in 1922 | |
  Madison Boulder Location in New Hampshire | |
| Location | Madison, New Hampshire, United States |
| Coordinates | 43°55′53″N 71°10′04″W / 43.93146°N 71.1678°W[1] |
| Area | 17 acres (6.9 ha)[2] |
| Elevation | 512 feet (156 m)[1] |
| Established | 1946[3] |
| Administered by | New Hampshire Division of Parks and Recreation |
| Designation | National Natural Landmark |
| Website | Madison Boulder Natural Area |
The Madison Boulder is one of the largest known glacial erratics in North America and among the largest in the world; it is preserved in the 17-acre (6.9 ha) Madison Boulder Natural Area in Madison, New Hampshire.[4] The boulder is a huge granite rock measuring 83 feet (25 m) in length, 23 feet (7.0 m) in height above the ground, and 37 feet (11 m) in width. It weighs upwards of 5,000 short tons (4,500,000 kg). A part of the block is buried, probably to a depth of 10 to 12 feet (3.0 to 3.7 m).[4] It was acquired by the state from the Kennett family in 1946.[3] In 1970, Madison Boulder was designated as a National Natural Landmark by the National Park Service.[5]
- ^ a b "Madison Boulder State Geologic Site". Geographic Names Information System. United States Geological Survey, United States Department of the Interior.
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