Tag Archives: exfoliating domes

It’s Alive!!

Cannon Cliff. The Beast of the East. For young aspiring trad climbers in New England this is the test piece cliff. From the beginning of my climbing I was taught to have a special respect for the dangers and challenges of climbing on Cannon Cliff. No doubt, this is for good reason, as any one who stares up at it can tell from the relative size of the talus slope to the size of the cliff. Of any cliff in New England, its safe to say that this is where the largest and most frequent rock fall occurs. While none of the major rock falls have resulted in fatalities, loose rock, caused by the same forces as the rock fall, has been responsible for  all but two of the climbing related deaths on cannon, and significant majority of the accidents. (all of the deaths but two have happened on one notoriously loose route as well, Sams Swan Song. See here, here and here for examples)

A recent walk along the cliffs base after a day of cragging made me mentally catalog the recent major rock falls of the past few years. With more frequent visits to cannon and a resulting increased familiarity with it, I’ve come to realize that this cliff is very much alive. At the hands of geologic forces set in motion hundreds of millions of years ago, combined with weathering events happening each and every day, this cliff is constantly changing, dangerously shedding old skin for new.

How & Why

Exfoliation Domes

While I am certainly no expert on the subject, I’ve gathered some relevant information from a few different sources to present a broad picture of whats going on here, so get ready to get learned. As Imortal Technique says (and appropriately for geology facts) I’m about to drop knowledge so heavy it leaves the earth un-balanced. Cannon Cliff, along with other outcrops of Conway Granite, were formed roughly 180 million years ago as bubbles of magma that penetrated the earths crust thousands of feet under now extinct volcanoes. As a geologic reference this was when all of the continents were joined as the last great super continent, Pangea. Here, under the massive weight of earth and mountains above them, these bubbles cooled and solidified. The weight of the earth above these bubbles, called plutons by folks in the know, is referred to as overburden. This overburden is eventually removed through mountain uplift and erosion, bringing these plutons up to the surface. Once the overburden is removed, the pluton is no longer under compression and starts to expand. As the force from this expansion reaches a certain threshold, the outer more rapidly expanding rock sheers off. This can happen in stages forming a number of layers separated by what are called relaxation joints or stress relief fractures. This causes the recognizable onion peel look of exfoliation domes.

(Some cool resources regarding this):

Beyond Granite: The Geology of Adventure by Sarah Garlick

Exfoliation Domes


Geoff approaching the slabs on Cannon which have the “peeling onion” layered look common among exfoliation domes


Once the rock is exposed two types of weathering affect it in such way as to make it even more loose and unstable. Mechanical weathering happens when water gets into cracks in the rock and freezes, expanding and pushing the rock further apart. The second kind of weathering is called chemical weathering and happens when certain elements in the rock react with elements in water or air causing the rock to dissolve or crumble as bonds are broken.


I’m using this equation to give a false sense of credibility to my words. Actually, its the equation for carbonic erosion, more common on lime stone cliffs.


Recent Rockfalls

Cannon Annotated

Cannon Cliff, Summer of 2016 with rock fall origins and destruction pointed out.

Duet Buttress

Probably the largest rock fall in recent years. I believe this happened in 2013. In the picture below you can see the large white rock scar where the rock fall originated, as well as the treeless area at the base of the Duet rock climb.


Duet Rock Scar (upper left) and DZ (bottom right

This rock fall left pulverized rock dust across the ground and clinging to the cliff a few feet up. It completely obliteraed healthy trees, left pock marks on the lower part of the cliff and even bent over several bolts on a popular rock climb called Sticky Fingers. Check out this awesome gigapan image of cannon (gigapan ) done by Jim Surette. The high definition image allows you to zoom around the cliff. If you zoom in over the base of Duet you can see the pock marked slabs and destruction at the base. If you really explore you can even find some climbers.

Here’s a couple of old pictures showing the tree cover at the base of the cliff here before this rock fall.


From the Whitney Gilman looking north along the cliff base


Directly above where the rock impacted, on Raven Crack. You can see the vegetation that was there before the rock fall.

And another after shot!


Ted Climbing Lightening Cracks with the destruction from the Duet rock fall at the base below. Some revegetation after 3 years.

The Bung Hole


James Otey surveys the scene

If you refer back to the map of rock falls on cannon I posted earlier you’ll see an odd cave like feature called the Bung Hole. This is a section of incredible rotten rock between the classic climbs Moby Grape and Union Jack. Believe it or not there’s even a route that goes right through the bung hole. This rotten rock has eroded away leaving large overhanging roofs of more solid, but now unstable rock above. Some massive blocks have recently fallen out of there, last summer and then again early this spring.


Otey on Reppies Crack with remnants of the first rock fall below

The first rock fall here was relativly small and didn’t really affect the bases of any climbs. The second one was larger and spread to either side as well as further down the hill. The starts of Union Jack and Vertigo, to the north, are now open and covered in fresh debris, and a couple of large blocks even bounced over to the start of Moby Grape, destroying the rescue litter stashed there in the process. This latest round also took out the top section of the approach trail for this part of the cliff. All the photos below show the most recent destruction as of summer of 2016.

A little out of order but here is a shot looking down Vertigo, showing the formerly tree covered base.


Alex rappelling down vertigo with trees covering the base in August of 2015

Lesser Rock Falls

There’s been three lesser, but still noticeable rock falls as well. Around the same time as the Duet rock fall there was fresh debris found just to the south of Moby Grape. This Summer, a fresh scar and debris pile was noticeable on the Cannonade buttress, home to Matt Ritter’s two new mixed alpine routes from this winter. Finally, about a year ago there was a rockfall over on Henderson buttress that was significant enough to take out trees. Relatively few folks climb on that part of the cliff, however, making it not super significant.


Historic Rock Falls

While Cannon’s massive talus field is evidence that there have been many many major rock falls here throughout history, there are two significant ones in the past two decades worth mentioning.

The Old Man

Perhaps the most well known, and well understood of the rock falls was the demise of the Old Man of the Mountain. This iconic rock profile graced our license plates, state road signs and the New Hampshire quarter. I remember the day it came down, the flag at my elementary school was lowered to half mast to mourn the loss of New Hampshire’s official state emblem.


From, “The Geology of New Hampshire’s White Mountains”

I say this is probably the best understood of the rockfalls because the delicate nature of the profile was studied and noted as far back as 1906. In fact, starting in 1916 measures were taken to secure the rock that comprised the profile. Many of these attempts have left remnants that are still visible today including steel cable, metal arms and epoxy drainage systems.  Before I-93 was built the NHDOT went so far as to do a seismic study to determine if blasting and other construction processes would cause enough vibration to knock the profile down.


Jay Conway cruises up “Lake View” Which finishes atop the Old Man. Reinforcing bars that used to hold the Old Man in place hang off the cliff

On his way down the Old Man impacted the slabs at the northern end of Cannon. To this day a lot of loose rock that is unmistakably from the old man litters ledges across the slab. A few years ago I dodged a pinwheeling rock set loose by my partner in this area. It had a steel bar epoxied to it that was clearly part of the old man. A route below the Old Man, Consolation Prize, used to have a finger tips thick crack that was climbed on the second pitch. After the old man fell, it was found that this crack was now as wide as a few inches (thick hand jams). Whether this is from rock impacting the slab and causing it to move, opening the crack, or it happened independent of the Old Mans demise, it certainly illustrates how shockingly mobile massive slabs of rock can be on the cliff side.

Whaleback Crack

Just South of the old man, was an even larger rock fall a few years prior. Here, in 1997, a feature known to climbers as the Whale Back Crack fell off. This massive rock fall hit the talus slope with such force that it was picked up on seismegraphs and created a rock slide 500′ wide by 1/2 a mile long. A large block, believed to be from the crux of the route, made it all the way down to the bike path along the floor of Franconia Notch. To this day the smooth white slab left behind can still be seen. Again, here’s the Gigipan image   of Cannon done by Jim Surette. You can find the location of Whale Back Crack by finding the slabs at the north end and following the cliff to the south where the slabs transition to a more vertical wall. in this area you can see a section at the base of the cliff that looks like recovering vegetation. Straight above here is the smooth rock scar.


Whalback Crack rock fall, taken from “The Geology of New Hampshire’s White Mountains”

Shortly after it fell, a few locals climbed though “the Zone” as it’s now known, and established a new route they called Whale Watchers.


Jon Sykes on the FA of Whale Watchers with the clean rock scar clearly visible.

This picture came from a write up Jon did on the rock fall and ensuing first ascent for Alpinist, check it out here.

In some ways it seems a miracle that Cannon isn’t a more dangerous place. In climbing, “safe” is a four letter word that we dare not speak. While we can mitigate risks we can never fully control them for a “safe” expereince, and every time one climbs they are subjected to risk, just like every time one gets into a car. what we can do is be smart, respectful of the danger and stack the odds in our favor by avoiding cliffs like Cannon when rock fall is more likely (spring, after rain, during the freeze thaw..), climbing on sections known to have cleaner more solid rock, and being mindful of the blocks we pull and push on.

After Thought

Cannons exfoliation is far from the only geologic processes happening in Franconia Notch. Frequent mass Wasting (read, landslides) on the east side of the notch also contribute to an ever-changing landscape. In the time span of the most recent rockfalls , there have been two landslides on the east side. Neither of these have been as serious as those in the past some of which have covered the road on the floor of the notch with over 12′ of debris. Here are two photos, again from “The Geology of New Hampshire’s White Mountains” that show the scope and scale of land slides on the east side of Franconia Notch. (click on either image to see a larger version)


Brain Fodder

If you’re as curious about the geology of the mountains you play in as I am then I highly recommend checking out these books that are both incredible informative and easy reading.

The Geology of New Hampshire’s White Mountains

(Holderness School friends, one of the authors of this book is an Alum)

Flakes, Jugs, and Splitters: A Rock Climber’s Guide to Geology

by Sara Garlick

Sara is a local crusher of climbing and science who, as well as writing a climbing centric geology book, curated a museum show focused on the geology of adventure in the White Mountains. While the exhibit has ended, the work lives on in the Gigapan image I’ve linked multiple times here, this article she wrote for it,Beyond Granite: The Geology of Adventure, and this awesome video that was put together to promote the show.

Beyond Granite