Madison Boulder

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]

Madison Boulder Natural Area
Boulder, Madison, NH.jpg
The Madison Boulder as photographed in 1922
Madison Boulder is located in New Hampshire
Madison Boulder
Madison Boulder
Location in New Hampshire
LocationMadison, New Hampshire, United States
Coordinates43°55′53″N 71°10′04″W / 43.93146°N 71.1678°W / 43.93146; -71.1678[1]
Area17 acres (6.9 ha)[2]
Elevation512 feet (156 m)[1]
Administered byNew Hampshire Division of Parks and Recreation
DesignationNational Natural Landmark
WebsiteMadison Boulder Natural Area


  1. ^ a b "Madison Boulder State Geologic Site". Geographic Names Information System. United States Geological Survey, United States Department of the Interior.
  2. ^ "State Lands" (PDF). New Hampshire Department of Resources and Economic Development. July 2007. Retrieved September 19, 2020.
  3. ^ a b Lisa Mausolf, Preservation Consultant (March 2019). "New Hampshire State Parks: Mid-Century Modern (1945-1975): Historic Context Study" (PDF). New Hampshire Division of Parks and Recreation. p. 24. Retrieved September 19, 2020.
  4. ^ a b "Madison Boulder Natural Area". New Hampshire Division of Parks and Recreation. Retrieved September 19, 2020.
  5. ^ "Madison Boulder". National Natural Landmarks. National Park Service. Retrieved September 19, 2020. It illustrates the power of an ice sheet to move large blocks of fractured bedrock over substantial distances.

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