The face-shaped granite formation destroyed by weathering once was the state emblem
Twenty years after the Old Man of the Mountain collapsed, audiences around the world will now be able to explore the iconic symbol of New Hampshire through an online interactive 3D model created by Matthew Maclay, a graduate student in earth sciences at Dartmouth’s Guarini School of Graduate and Advanced Studies.
The face-shaped granite formation on the northeast side of Cannon Cliff in Franconia Notch State Park fell off the cliff on May 03, 2003, drawing international attention and dismay in New Hampshire itself. The rock formation is the emblem of the state.
As part of the research project, Maclay and collaborators Jesse Casana and Carolin Ferwerda at Dartmouth’s Spatial Archaeometry Lab performed aerial surveys of Cannon Cliff using a drone. They then reconstructed the now lost profile using original film negatives taken between 1958 and 1976 that documented the Old Man of the Mountain and surrounding area during maintenance conducted by the profile’s caretakers.
Maclay processed the imagery in the Planetary Surface Processes Computing Lab led by Marisa Palucis, an assistant professor of earth sciences at Dartmouth. By applying photogrammetry, a technique akin to the way that eyes provide depth perception, he was able to create a 3D model of Cannon Cliff with and without the Old Man of the Mountain.
Through this model, viewers can zoom around Cannon Cliff, which is approximately one mile across and 1,000 feet tall in size and see where the Old Man used to be located.
“Cannon Cliff is one of the largest cliffs in the eastern United States and it looms over a massive pile of rocky debris ranging in size from sand to boulders larger than cars,“ says Maclay. “It’s an enormous slope of loose rocks, which serves as evidence of the efficient bedrock weathering and rockfall that has been taking place since the last ice sheet retreated, around 12,000 years ago.“
In his research, Maclay is studying how climate-based processes break down bedrock physically and chemically in place, which in turn loosens and frees up the bedrock for rockfall.
“The Old Man of the Mountain may have weighed nearly 2,000 tons, when it collapsed,“ says Maclay. “While 3-inch turn buckles had been bolted into the Old Man to try and prevent it from falling, the actual strength of the granite was degraded over centuries and that’s probably why it collapsed.“
(18.05.2023, USA: 05.18.2023)