Whitney Glacier makes a slow-motion tumble down a high cliff on Mount Shasta.

The Whitney Glacier, on Mount Shasta’s north side, is one of the mountain’s great features. The glacier flows through the chasm formed between Hotlum Cone, the main cone of Mount Shasta, and the secondary cone of Shastina. It is the longest glacier in California and the 2nd largest in volume. It is a magnificent river of ice, forming just below the summit and snaking over 2 miles down the volcano’s flank. It is one of the most awe-inspiring parts of Mount Shasta. However, the massive scale of Mount Shasta is such that it is often to overlook individual features in favor of the mountain as a whole. This is definitely the case with the Whitney Glacier and even more so with the glacier’s most noteworthy feature, its spectacular icefall.

The icefall is formed when the glacier encounters cliff composed of a large band of rock that is harder than other rocks in the vicinity. This hard band has resisted the scouring of the glacier more than the surrounding rocks. It is then necessary for the ice to pour off of the cliff in a spectacular cascade of crevasses and seracs. As the ice slowly descends the dense band of rock, it fractures and splits, opening up gaping cracks. These are dramatic evidence of the ice’s momentum. It is one of the most astounding sights on Mount Shasta and, though it is visible with the naked eye, it is one of those grand features that is overshadowed by the mountain’s overwhelming stature.

A view of the Whitney Glacier and its icefall between the Hotlum Cone and Shastina.

Glaciers are inherently dynamic, living ice perpetually carving away at the earth around them. They have helped create iconic landscapes like Yosemite Valley, as well as lesser known but momentous sights like Steens Mountain’s Kiger Gorge. Most of the large volcanoes in the Cascade Range are glaciated. Mount Shasta is no different, boasting 7 glaciers on its flanks. There are 3 small glaciers located on the southern flank while the 4 large ones are located on the north and east flanks. All of them continue to wear away at Mount Shasta, cutting into the rock as they creep slowly downward.

The glacier’s continual shaping of Mount Shasta is most readily visible just above the icefall. The creeping sheet of ice is slowly but inexorably cutting into the western slope of the Hotlum Cone, about 2,500 feet below the summit of Mount Shasta. As the ice cuts into flanks, it undermines the loose scree that forms much of Mount Shasta. The scree then collapses onto the river of ice, only to be carried away as the glacier flows down the side of the mountain.

The red lines indicate the flow of the Whitney Glacier. The yellow area is the collapsed zone. The orange line is the path of the debris being carried away as the glacier descends Mount Shasta.

The undermining of the side of the Hotlum Cone is not an event of the past. It is a process that continues at this very moment. Like at Mud Creek Canyon on Mount Shasta’s south side, the clatter of boulders falling out of the undermined area onto the glacial ice is a nearly constant sound. It is an awesome reminder that Mount Shasta has not reached its final shape. Regardless of whether the mountain ever erupts again, other natural forces are at work on its appearance. The mountain may have been forged by fire but now it is carved by ice.

The large terminal moraine of the Whitney Glacier.

The debris that is carried off by the glacier is ultimately deposited couple thousand feet lower down the mountain, forming large glacial moraines. A moraine is the leavings of the glacier’s carving activities. It can either be pushed ahead by the ice like a bulldozer or it can land on top of the ice sheet and be carried away and eventually deposited further down the mountain. The Whitney Glacier has a large, wedge-shaped terminal moraine, located at about 9,500 feet. This debris field is flanked by more typical moraines that have been pushed out of the way of the advancing glacier and now form lines of rock and other ice-cut detritus that lie alongside the still active ice. This is one of the two terrific examples of glacial moraines on Mount Shasta, along with the Hotlum Glacier’s incredible medial moraine.

Though not a well-known landmark, the Whitney Glacier icefall is one of the most remarkable features on Mount Shasta. As one gazes up at the north side of the mountain, be sure to look for the river of ice flowing between the peak’s main cone and Shastina. It is easy to spot the icefall. As you look up at this incredible formation, know that at that very moment Mount Shasta is still being formed. It is a living mountain, its angle of repose not yet reached, its form is still being refined, just as we are.