Sounding the Bow

How we moved a vanishing glacier to the center of Canada’s fastest growing city

This post documents some of the process behind Herald/Harbinger, a permanent public artwork located in Calgary, Alberta, created by Ben Rubin and Jer Thorp. The artwork sits on the traditional territories of the people of the Treaty 7 region in Southern Alberta, which includes the Blackfoot Confederacy, the Tsuut’ina First Nation, and the Stoney Nakoda. The City of Calgary is also home to Métis Nation of Alberta, Region III. The project’s glacial sensor station is located in the traditional territories of the Blackfoot Confederacy, the Ktunaxa Nation, and the Tsuut’ina First Nation.

“Glaciers and the mountains around them force the human mind to think in different ways, and at different speeds.” — Robert Macfarlane

The Bow Glacier, some 750 metres of ice sticking out like a tongue from the Wapta Icefield, is the last stub of a great mass of ice that once flowed far to the east, carving out the wide river valley which bears the same name. The ice, at its peak, measured more than a kilometre in depth. Twenty two thousand years ago it stretched itself east out out of the Rockies, into the foothills, touching briefly the great plains on which the city of Calgary now sits.

The Bow Glacier in 1924. Photo by Harmon Byron.

Three hundred years ago the glacier’s ice would have flowed into Bow Lake, calving off small icebergs in the spring and summer. At the turn of the last century, the glacier came down past the tree line, its terminus blending into the mossy soil of the alpine forest. Today the ice’s edge sits more than three kilometres away from the lake. Ice still calves off and tumbles into water, but it is into a new, diminutive lake that has formed over the last decade on a small rocky shelf. I don’t think I was the first to name it Bow Pond.

As you’re reading this, meltwater is beginning to flow from the glacier and down from the Pond to the Lake, tumbling down a series of waterfalls. The water carries with it dust, tiny motes of rock scraped from the rock bed, evidence of the glacier’s heavy movement. In streams, this ‘rock flour’ gives the water the appearance of diluted milk. Down in the lake, the particulate collects to colour the water a brilliant, unforgettable turquoise. To the southeast, water drains into the Bow River, which elbows through Lake Louise and Banff and Canmore and Cochrane and Calgary, on its way to Hudson Bay.

Bow Glacier, Bow Pond, Bow Lake. Photo by Shah Selbe.

If you drink a glass of water today in Calgary, there’s about a fifty-fifty chance you’re tasting some of the glacier. If you’ve lived in the city your whole life, your body is infused with those blue limestone molecules. The mountains are, quite literally, in your bones.

It takes some time for the water from the glacier to make it to the city. If you were to drop a small toy boat into Bow Lake on a Sunday morning, and if it was lucky enough not to get caught up or sunk along the way, you might step out onto the Peace Bridge in Calgary early Wednesday evening and watch it drift below you. If you’re not that patient, you could put the boat in your car, pull off of the gravel shoulder and onto the Icefields Parkway and head southeast from the lake to the city. It would take you two and a half hours, if the traffic wasn’t too bad.

Last summer a helicopter flew a low half circle over the Bow Glacier before touching down on a deep patch of snow just a few metres from a rocky outcropping. We unpacked our ice axes and crampons and a half-dozen neatly packed Pelican cases, and over the next three days we built a seismic observatory along the edge of the ice. Data from the station is now relayed four kilometres via radio bridge to the Num-Ti-Jah lodge at the edge of Bow Lake, then uploaded via satellite. Within five minutes the cracks and shifts of the ice are translated into sound, and sent out of a set of sixteen speakers, filling the plaza in front of Brookfield Place, a shiny 56 story office building which opened in the fall.

In the building’s entrance, a tall set of seven LED arrays represent the same data as distortions in a field of light. At night the light casts out onto the stone in plaza, some 7000 unique pieces of granite, cut to depict to the geological forces of the glacier’s ice field. In the winter the sound and light are muted by freshly fallen snow.

This morning, the Bow Glacier is talking to the city, and the city is talking back. The ice burbles and cracks and pops. Calgary responds with the sounds of the eastbound CTrain passing by on 7th Avenue, with the rumble of a full garbage truck, with the clattering steps of the well-heeled shoes of a commuter crossing the pavement. On the LED arrays, traffic patterns from around the city and pedestrian paths through the plaza share space with data from the glacier, in a conversation that never quite stops. For a long stretch in the late afternoon the glacier falls quiet, its whispered signal barely heard behind the noise of rush hour. Tonight, when the city is quiet, the plaza will come suddenly alive, an ice fall 180km away echoing out into the street.


I was born in Alberta in 1975, delivered into Trudeau socialism, my first strident cries answered by the sounds of big data. Edmonton’s old Royal Alexandra Hospital, renovated many times since opening in 1899, balanced its austerity with modern machines, a product of Canada’s booming economy and solid faith in cooperative health care. One of the newest those machines sat in the delivery room, beeping occasionally and spilling reams of paper into a metal tray. It was a cardiotocograph, a fetal heart monitor, and it was measuring my heart beat, inside of my mother’s womb, two hundred times every second.

My brain can’t help but read the output from a cardiotocograph as a topography, a long linear series of craggy peaks. Unlike the smooth beeping electrocardiogram lines we’re used to seeing on medical TV shows, the heart rate line is noisy terrain, a jagged line that dips up and down with seemingly little pattern. This is the fast heart rate of the fetus, rendered alongside all of the other liquid movements in the womb.

A cardiotocograph recording

The cartiotocograph works by sending short pulses of sound between two transducers. By analyzing that the time the signal takes to get from one transducer to the other, the machine can tell us something about the velocity of liquids in the womb. Tuned finely, it catches the fast back and forth movement of blood in the tiny heart of the fetus.

Our seismic observatory on the Bow does something of the opposite. Three sensors called geophones measure the movement of the rock bed along different axes (north/south, east/west, up/down). Small shifts in the limestone move a tiny magnetic mass suspended in a wire coil inside each device; this movement is converted into electricity, and in turn to a digital signal.

When we’d finished installing the sensors, a scant three hours before the helicopter was due to pick us up, I copied and pasted a chunk of the data from the station and I wrote a bit of code to draw it onto my laptop screen. It wasn’t much to look at, just a long bar chart, but there was no doubt that there was signal there. Not the TV snow of random numbers, but something more structured, something that felt… well, it felt like it was alive. Up on the mountain, when the wind wasn’t blowing, there was an eery, complete silence. Watching the data scroll by on the screen, though, I could see that the ice was not as it appeared; that its still belied a quick and constant movement.

Later, at home in Brooklyn, I wrote another small program that turned live feed from the seismic station into a neat black line against a white background. Running in real time it was nothing but a blur, so I added a bit of code so I could pause the screen with a press of the space bar. And there suddenly, was that noisy terrain again, the jagged trace of the cartiotocograph.

8 seconds of activity on the Bow Glacier

In some ways, this parallel wasn’t a surprise. After all, both machines are recording movement, both are listening for signal against a backdrop of water. The glacier is, like the fetus, governed by cycles of time, albeit at different scales. The seasonal snowfall, the daily thaw and freeze of the ice, the rattle of a boulder caught in the melt.

Looking at the line brought to mind an easy cliché, that our sensor station was capturing the heartbeat of the glacier. But the data, over time, will tell a different story. Our machine beside the glacier, anchored into the limestone ridge, is not measuring a birth, it is measuring a death. A shifting, melting, prolonged, mostly inevitable death.


Standing in the center of the plaza at First and Seventh, you are in a place that shouldn’t exist, a somewhere that is at the same time 2,450 metres up in a 60 million year-old mountain range, and in the center of Canada’s fastest growing city. It is a kind of rift in public space. You are at once at the edge of the ice of the Bow Glacier, and in the midst of tall skyscrapers filled with oil & gas company offices. You have one foot in the Pleistocene, the other in the Anthropocene. In this strange, improbable space, the everyday gains new meaning as the ring of your cell phone is answered by the sharp crack of the glacier.

The Bow Glacier in 1902 (left) and 2002 (right). Photos by the Vaux Family.

Herald/Harbinger is a permanent public artwork. In the same way that the new tower’s gleaming glass has changed the city’s skyline, the sound light and stone of the piece casts a lasting mark in the urban landscape. For Calgary’s commuters and residents of the downtown core, the glacier is now there with them every day. It’s as much a part of the city as the Saddledome or the sprawling +15s.

Herald/Harbinger is a constant signal that you are never really apart from nature. A reminder that, although your view of the mountains might be blocked by fifty six stories of gleaming glass, you are still connected to them through the water you drink and the air you breathe.

Herald/Harbinger is a living wake. In fifty years or so the Bow Glacier will have receded up to the level of our seismic station. In the years after that, the signal from the mountain will start to grow quiet. Eventually the sounds of the ice will fade, and the plaza will again sound only with the sounds of our footsteps and the thrum of our vehicles.

Until then, the Bow has a voice in the city.

“We live surrounded by ideas infinitely more ancient than we imagine, and yet at the same time everything is in motion.” — Pierre Teilhard de Chardin
A commuter walks behind the Herald/Harbinger LED screens on the building’s +15 level. Photo by Brett Gilmour.

Herald/Harbinger is located at the corner of 7th Ave SW & 1st St. SW in Calgary Alberta. It is open to the public 24 hours a day, 365 days a year.

The artwork was commissioned by Brookfield and supported by Calgary’s Public Art Program. Special thanks go out Parks Canada, and Simpson’s Num-ti-jah Lodge.

Artists: Ben Rubin & Jer Thorp

Consulting Glaciologist: Dr. Jeff Kavanaugh

Sensor Station Design & Installation: Shah Selbe & Jacob Lewallan, Conservify.org

Special Thanks to Rina Greer, Noa Younse, Kate Rath, Brian House, Matt Thorp, Michele Gorman, David Hotson and Michael Konow