Johnston Creek originates north of Castle Mountain in a glacial valley southwest of Badger Pass and south of Pulsatilla Pass, at an elevation of 2,500 meters. The creek flows southeast between Helena Ridge and the Sawback Range, and then south through a gorge known as Johnston Canyon. The stream empties into the Bow River, south of Castle Mountain, between Banff and Lake Louise, at an elevation of 1,440 meters.

As Johnston Creek approaches the Bow River, it flows through a a large canyon formed by erosion over thousands of years. The creek has cut through the limestone rock to form sheer canyon walls, as well as waterfalls, tunnels, and pools.

A popular hiking trail follows the canyon and leads to a meadow within the Johnston Valley above the canyon. The first part of the trail consists of a constructed walkway with safety rails and bridges, while the last part of the trail is natural and more rugged. Within the meadow are the Ink Pots, which are six blue-green spring-fed pools. Ice climbing is a popular activity on the frozen waterfalls in winter.

The formation of canyons can be related to the natural tendency of rivers to reach a base line elevation. This is generally defined as the point at which the river reaches the elevation of the large body of water into which it will drain. Essentially, the larger the difference in height between the river and its inlet into a large lake, the more energy the river will expend in the process of erosion. Much of this energy will be expended towards increasing the efficiency of the drainage system, and facilitating a speedy drop in elevation.

In the case of Maligne Canyon, the river suddenly found itself elevated in a hanging valley as the Athabasca Glacier carved a much deeper valley than its smaller tributary. To facilitate drainage to a now distant valley bottom, the river expended incredible amounts of energy to deepen the channel into the narrow, deep canyon visible today. Other rivers, like the river flowing down Johnston Canyon, were forced to find new channels when their ancestral streambeds were blocked. A landslide dammed Johnston Canyon’s original channel. In other cases, glacial debris may have the same affect.

Most of canyons are very recent additions to the landscape. In most cases, the creation of canyons coincides with the departure of glaciers from their valleys. As the ice began to melt, it not only released ancestral river beds from their icy prison, but it also released immense amounts of water. So much water was released that the rivers were provided with an incredible erosional potential. This extra water supply allowed them to rapidly alter their channels, and the down-cutting may have begun almost instantly. As the glaciers largely, eventually the initial deluge subsided, and the rate of erosion slowed accordingly, but didn’t stop. Most of our canyons continue to deepen even today. While you stand at the top of Maligne or Marble Canyon, the valley floor is slowly being etched and scoured. The rate may have slowed, but the process is unrelenting.


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