Description - Madison Boulder is a huge granite rock measuring 83 feet in length, 23 feet in height above the ground and 37 feet in width. It weighs upwards of 5,000 tons. A part of this roughly rectangular block is buried, probably to a depth of ten to twelve feet. It is made of fine-grained feldspar and larger quartz crystals that welled up under great pressures from a molten mass deep in the earth over 200 million years ago. Upon cooling, the molten rock hardened.
- As recently as 1835, geologists believed that huge boulders isolated in their surroundings like Madison Boulder had been washed to their present locations by great floods which are said to have occurred in ancient times. Today, it is believed that these large boulders or "erratics" were moved various distances during the last Ice Age. Thousands of years ago New England was blanketed by a great sheet of packed snow and ice. The ice pack moved slowly across the landscape, sometimes advancing, sometimes retreating. More than a mile thick, it flowed across even the highest mountains in a generally southeasterly course. As the ice passed over rock outcroppings, blocks of otherwise resistant material, were broken from the parent rock along naturally occurring fracture lines. Usually the fragments were carried only a short distance allowing their source to be easily traced.
Most authorities trace Madison Boulder to the Whitton or White ledges 12.5 and 4 miles respectively, to the northwest. However, as few maintain that the boulder so closely resembles one of the four types of rock that form Mount Willard in Crawford Notch, twenty-four miles to the northwest, that the ice sheet must have brought it from there. Madison Boulder lies on "glacial drift," unsorted sediments left by the retreating ice sheet.
Madison Boulder is the largest known erratic in New England and among the largest in the world. The seventeen-acre site was acquired by the state of New Hampshire in 1946. In 1970 Madison Boulder was designated a National Natural Landmark by the U.S. Department of the Interior.
Recreation - This 17 acre natural site is open year-round for sightseeing and picnicking.
Climate - Winter can be cold with average temperatures ranging around 19 degrees Fahrenheit. The cold temperatures humidity bring heavy, water-laden snow to all parts of the state. Spring begins in mid-March and lasts through May. This time of the year is referred to as mud season in the mountains. The sugar is flowing early in the season and wild flowers bloom toward the end of it. Summer is the busiest season of the year for the tourism industry. This is an excellent time to travel, mountain roads are open and most of the mud has dried. Average summer temperatures range around 68 degrees Fahrenheit. Fall brings the leaf lookers to see the spectacular colors of the deciduous trees. Expect to see bus loads of people enjoying the crisp fall New England weather.
From Madison, travel north on SR 113 approximately 2 miles.