Just over a year ago, New Hampshires
famous Old Man of the Mountain collapsed from his perch on Profile Mountain
in Franconia Notch State Park. The stone structure was one of the largest naturally
occurring human profiles in the world and was the beloved emblem of the state
of New Hampshire. The Old Mans profile showed a mans face with a
stern but warm expression, which New Hampshire residents proudly said emphasized
their resolute, independent and pioneering spirit. Since the New Hampshire Legislature
made the Old Man the official emblem of the state in 1945, he has graced official
stationary, the state quarter and every tourist trinket imaginable.
This 2001 telescopic view of New Hampshires Old Man of the Mountain shows the natural profile created by overhanging blocks of granite. On May 3, 2003, residents discovered that the profile had fallen, and since then geologists and the state have been discussing possible ways to rebuild or memorialize the historic site. Copyright AP/Jim Cole; courtesy of Brian Fowler.
The Old Mans profile was visible when an observers line of sight incorporated several overhanging blocks of granite, balanced on the mountain cliff by the cantilevering of the lowest chin block by the successively more massive blocks above. Measuring about 45 feet high and 26 feet wide and weighing approximately 7,200 tons, the intricate profile resulted from chemical weathering and freeze-thaw rock falls from the glacially eroded face of Profile Mountain. These same processes were also responsible for its ultimate demise.
The absolute age of the Old Man is unknown, but it probably formed between the retreat of the last continental ice sheet (approximately 12,000 years before present) and its discovery in the early 19th century by early settlers of the region. The ice sheet carved the cliffs of Profile Mountain, over which the Old Man came to preside, by eroding deep into the Pemigewasset Valley. Once the ice sheet melted, gravity, ice-wedging and water began eroding the cliffs to form an apron of rock-debris slopes. The nested blocks of granite from which the Old Man emerged were left protruding from the crest of cliffs.
The Old Mans remarkable formation relied on selective freeze-thaw breakage along the intersections of a series of subhorizontal and subvertical joint sets formed in the granite body. Subsequent frost-wedging and splitting of blocks occurred as water in the joints froze, driving the blocks apart sometimes resulting in the mass wasting of granite blocks off of the cliff face. The selective breakage between the joints created the triangular shape and delicate cantilevering of the chin and upper lip blocks, which were critical to the profiles stability.
Surveyors first recorded a description of the Old Man in 1805. The most famous literary acknowledgement and tribute to the Old Man was Nathaniel Hawthornes short story The Great Stone Face, published around 1840, endearing the Old Man to the hearts and souls of New Hampshires residents.
In the 1850s, a grand hotel (the Profile House) was built in Franconia Notch. Its guests visited the notch, seeking inspiration from the profile and its surroundings. In 1872, the Appalachian Mountain Club and a Boston-based newspaper published an article on the Old Man that first documented its delicate stability. At the turn of the century, residents of Franconia began a concerted effort to stabilize the Old Man. And in 1916, residents installed by hand approximately a dozen steel tie rods and turnbuckles to secure blocks on the Old Mans forehead, in order to maintain the overall center of gravity, as it was understood at that time.
In 1954, nine years after the New Hampshire legislature made the Old Man of the Mountain the official emblem of the state, State Geologist Ralph Meyers and other officials reported to the legislature that the profile was quite unstable, despite the previous good efforts to secure its forehead portion. Moreover, they pointed out there was a critical lack of understanding regarding the structural mechanisms that controlled the tenuous stability of the lower blocks.
Driven by proposed highway construction through Franconia Notch, various informal studies were undertaken, beginning in the late 1950s. However, it was not until 1976 that the New Hampshire Department of Transportation completed the first mechanical and structural analysis of the support mechanism and stability of the entire rock structure. That work recommended constructing the I-93 Parkway in the notch below if blasting and other construction vibrations were kept below ambient levels or natural vibration.
Following these recommendations, the highway was successfully completed in 1986, without damage to the Old Man. Over the past several decades, volunteers and crews from the states Department of Transportation continued a yearly maintenance schedule by giving the Old Man a makeover of epoxy resins and cement to seal cracks and fractures on its upper surfaces. They hoped to minimize the infiltration of water, which was always presumed to be the Achilles heel of the Old Man.
Beginning of the end
The Old Man consisted of Jurassic Conway granite, which is a coarse-grained, pink biotite-granite. The pink, or red phase, of the granite has been quarried for approximately 100 years in New Hampshire for building and dimension stone. In 1977, State Geologist Glenn Stewart supervised a detailed study of the Conway granite to evaluate its geothermal potential. As a result, a 3,000-foot borehole was drilled into the granite to retrieve a core sample for comprehensive mineralogical and physical study. The report from this study ultimately became a valuable source of information related to the geology and mineralogy of the granite that made up the Old Man, and provided insights into its weathering characteristics and subsequent demise in 2003.
State Geologist David R. Wunsch collects samples of remnants of the Old Man of the Mountain for analysis. Courtesy of David Wunsch.
Detailed mineralogical analysis shows zones of intense weathering and alteration of minerals in the granite, such as perthite. Approximately 40 to 90 percent of the perthite in localized, highly weathered zones was chemically altered to kaolinite. Zones of intense alteration occur throughout the granite, penetrating hundreds of feet down into the rock mass. Thus, alteration along fractures most likely penetrated deeply into the granite cliff that supported the Old Man.
Petrologic analysis of samples from the fallen forehead block identified after the Old Mans collapse clearly showed weathering rinds along fracture planes, versus the fairly unweathered, competent core of the boulder. The fracture rinds show the chemical alteration of plagioclase minerals into phyllosilicates (for example, sericite) and the existence of numerous micro-fractures containing iron stains, most likely from the decomposition of biotite, one of the main constituent minerals in the granite. While efforts were made to seal fractures from major inflows of precipitation, there was no way to prevent the microscopic migration of water that reacts with the mineral grains between the conjoined blocks of granite.
A close aerial examination of the rock-fall scar after the Old Mans collapse revealed that significant grus (weathered granite) had formed in the fracture planes exposed on the surface, and that soil had infilled voids where fractures were enlarged. Moreover, researchers observed green moss on the rock face that would have been the back wall of the cavern a large void that had formed behind the chin block indicating that sufficient wind-driven moisture was getting behind the blocks to support vegetation. Investigators also saw water seeping from the fractures along the rock wall behind where the former profile blocks rested. This evidence indicated that even the best efforts to seal off the fractured granite were insufficient in the harsh climate of the White Mountains, where frost wedging had been subtly forcing the blocks apart.
On the morning of May 3, 2003, New Hampshire residents, as well as the rest of the world, woke up to the shocking news that the Old Man had fallen; it was a day of mourning. Looking for an appropriate official response, state officials soon realized that there were few precedents for what a state can do when it loses one of its most significant geological features. And in the case of New Hampshire, the incident was especially significant because the citizens had an almost sublime, personal relationship with their state symbol.
In this aerial view of the Old Man after its collapse in May 2003, weathered granite is visible along the joint and fracture planes that existed between the fallen blocks. Moss (green area) grows on the cliff face, where the cavern existed behind the chin block. Also, a wet area on the cliff face (lower left) indicates that water was making its way down through the fractured rock. Three turnbuckles (top center) remained after the fall. Photo by George Bliss.
Immediately after the collapse of the Old Man, New Hampshire Gov. Craig Benson assembled the Old Man Restoration Task Force, which comprised leaders of the New Hampshire House and Senate, civic leaders and state officials, including the state geologist, who is first author on this story. Chaired by former New Hampshire Gov. Stephen Merrill, the task force was charged with looking at all options, including rebuilding some facsimile of the Old Man, creating a museum and using technology to provide visitors some visual representation of the profile at the former viewing site, which had attracted tourists from around the world.
The state geologist provided technical support to the task force, compiling information and producing reports that characterized the difficulties in rebuilding or carving a replica of the Old Man in the granite cliff. Using Mount Rushmore as an analog, the state geologist showed that the difficult logistics for construction, compounded with the immense removal of rock necessary to reach competent granite for sculpting and the associated environmental costs to one of the most scenic valleys in New Hampshire, would be quite impractical. And in one of those rare cases where public opinion coincided with scientific reality, the option of rebuilding the Old Man or placing a prosthetic structure at the Old Mans former site was rejected by New Hampshire residents by an order of five to one.
In the end, it is clear that the same geological processes that created the Old Man ultimately led to his demise. The White Mountains are in the destructive phase of their life cycle. Tenacious chemical weathering, frost-wedging, mechanical stress and gravity all have conspired to send the Old Man down to the talus pile below.
Its a true example of geology in action. Rust never sleeps.