MADISON — The National Park Foundation has awarded the Madison Boulder Geological Wayside Park a 2012 impact grant, which will help spruce up the state park and make the road and path to it — and information about the rock — more accessible.

The Madison Boulder sits in the middle of the woods off Boulder Road in Madison, at the northwest corner of the Chain of Ponds. From the air, it's not hard to find, and a search for it on Google Earth gives a quick perspective on how large the 5,000-plus-ton single piece of stone is — its top is larger than the roofs of the houses in the neighborhood.

It might not have the glossy touches of the better-known geological landmarks in the White Mountains, but its massive size — 87 feet long, 23 feet wide and 37 feet high — makes it a remarkable specimen of a glacial erratic. It's remarkable in that it's the granddaddy of them all.

Glacial erratic are rocks that were transported by glaciers from other formations, left in place when the glaciers melted. In New England, the continental glacier flowed south from Labrador, breaking off huge chunks of the upland bedrock. The Madison Boulder, made of Conway granite, likely comes from a place two miles northwest of its present site.

“This important grant will permit us to complete renovations to the park that will improve and better interpret the remarkable experience its hundreds of visitors and school groups have each year,” said Brian Fowler, chair of the Madison Boulder Advisory Commission. “These improvements will enhance the experience of visiting the site and will help visitors better understand how unique the Boulder is as the largest glacial erratic in North America.”

Phil Bryce, director of the state Division of Parks & Recreation, said the grant will fund improvements to the access road, the walking and handicapped access trails, and the site's security. The funds will also provide for the installation of geologic and natural history signs and kiosks, Bryce said.

The impact grant supports the park's Facility, Access & Interpretation Improvement Project.

Impact Grants contribute up to $10,000 to help parks with additional funding for projects.

The site was a gift to the state in 1946, in memory of James O Gerry and A. Crosby Kennett.

At the Madison 2012 town meeting, voters approved a quick claim deed to the state for the access road to the site.

syoungknox@newstote.com