About the Park
Madison Boulder Natural Area is home to the largest known glacial erratic in North America, and among the largest in the world. Madison Boulder is a huge granite rock measuring 83 feet in length, 23 feet in height above the ground, 37 feet in width, and weighs upwards of 5,000 tons! The 17-acre site was acquired by the state of N.H. in 1946. In 1970 Madison Boulder was designated a National Natural Landmark by the U.S. Department of the Interior because the enormous erratic, "is an outstanding illustration of the power of an ice sheet to pluck out very large blocks of fractured bedrock and move them substantial distances." The boulder was deposited in this location during most recent period of glaciation, around 14,000 years ago.
Madison Boulder Natural Area brochure
Are pets allowed at Madison Boulder Natural Area?
Pets are permitted in the park. See the NH State Parks Pets Policy for more information.
Keep Your Parks Clean
Through the Carry-In/Carry-Out Program, you can help us keep your parks clean and beautiful by carrying out whatever you carry in. Thank you for your cooperation and remember to recycle.
Access for Persons with Disabilities
Visit our Accessibility page. For more information on specific accessibilty needs or questions, please contact the individual park office directly.