The Evolution of Cannon Cliff

Our Mission

In a collaboration between Dartmouth College, Franconia Notch State Park, scholars of the White Mountains from various organizations, and local community members, we are working to better understand the forces driving bedrock weathering and rockfall at Cannon Cliff. Our goal is to bring the history and evolution of Cannon Cliff to life by studying the processes that shape it. Franconia Notch is a special place enjoyed by thousands of visitors each year. We hope to contribute to community knowledge and appreciation of the history, geology, and ongoing processes shaping this remarkable site.

Why study Cannon?

Frequent Rockfall

Cannon Cliff is home to the most extensive talus slope in the Eastern USA. The blocks that comprise the upper talus are evidence of the frequent rockfall that takes place. Different colored blocks on the talus can indicate more recent or older rockfall events, as rock surfaces are discolored over time through weathering.

Soil Production

The weathering of bedrock produces soils and dictates soil chemistry, which is critical to agriculture and the growing of food all over the world. Massive boulders are progressively weathered to smaller and smaller grain sizes at Cannon, causing them to settle and travel down the talus slope. It's easy to spot places where soil is being produced.

Intense Weathering

The harsh climate of the White Mountains leads to physical and chemical weathering of the bedrock. These processes are impacted rock composition, climate, topography, and more. At Cannon Cliff, the intense seasonal climate variations support both physical and chemical weathering processes. Vegetation root systems gradually wedge apart rock, abundant water dissolves and chemically alters minerals in warmer seasons, and icy frost weathering damages and wedges rock in the winter.

Hazards & Public Interest

The exfoliating granite of Cannon Cliff leads to frequent rockfalls, including the 2003 collapse of the Old Man of the Mountains. In a large rockfall in 1997, one boulder ended just a few feet from the popular Franconia Notch bike path. Additionally, Cannon is a popular climbing destination. Better understanding past and present rockfall dynamics may allow people to make better informed decisions about how to recreate safely in the area in the future.

What we're doing

Our research is actively underway, but here's a preview of what's to come.

3D Modeling

The Old Man of the Mountain in 3D20 years after its fall, explore the icon of New Hampshire like never before

With images taken from multiple different angles and locations, we can create a 3D model of an object. Above is our first interactive 3D model of Cannon Cliff. By creating multiple models over time, we can directly measure changes in the geometry and volume of the cliff face and talus below. We can also use these models to do basic descriptive analyses of geologic structures across the cliff.

GPS Surveying & Temperature Probes

We adhere small temperature sensors on the cliff (left) to measure bedrock temperature throughout the seasons. We measure each sensors location to within a few centimeters using GPS surveying equipment (right), which allows us to calibrate thermal data and map our sensors on the 3D Model.

Bedrock weathering processes are temperature dependent, so by measuring bedrock temperature across the cliff for a full year, we can learn about what types of weathering might be most active, when, and where.

Thermal Imaging

Visible Image

Thermal Image

Using various wavelengths to image the cliff allows us to map features and measure bedrock temperature remotely and across the entire cliff. The left image is normal reflected visibile light, while the image on the right is from infrared light due to thermal emission from the bedrock.

Depending on ambient lighting and thermal conditions, thermal imaging can be useful for mapping ice, water, and other surface differences on the cliff face.

Historical Climate Data Analysis

Climate datasets from the Mt. Washington Observatory and Hubbard Brook Long Term Ecological Research contain decades of detailed climate measurements and are invaluable for our research on how the harsh climate at Cannon Cliff contributes to rockfall and erosion.

Measure Bedrock Composition

Using a handheld X-Ray Fluorescence (XRF) detector, we can measure minute variations in the composition of the granite and diabase across the cliff. We expect bedrock composition is related to the extent of weathering the bedrock has experienced, with specific compositions being more prone to weathering, and compositions changing due to weathering.

Historical Image Analysis

With historical images, we aim to understand the cliff as it was in the past, before the 2003 collapse of the Old Man of the Mountain and other rockfall events. We are using all of the images we can get to make accurate models. With historical imagery, we have created full 3D models of the cliff including the Old Man of the Mountain. Film negatives and contact slides are especially valuable, as they are free from secondary projection errors.

Photographic Prints

Credit: Museum of the White Mountains, Plymouth State University, Plymouth, NH USA

Postcards