Lewis and Clark Passed Here

By editor

Great Falls, Cascade County, Montana

In the summer of 1805, the expedition led by Meriwether Lewis and William Clark encountered one of the most formidable natural obstacles of their entire journey westward across the continent: the Great Falls of the Missouri River. These falls, a series of five distinct cascades plunging over 400 feet in total across a ten-mile stretch, presented a challenge not only of navigation but also of human endurance. The expedition passed through this region twice -- first on the way west in June and July 1805, and then again on their return in July 1806 -- each time confronting the raw power of the falls and the rugged terrain that surrounds them.

The geological story of the Great Falls is written in the very rocks over which the Missouri River roars. The falls cut through ancient Precambrian metamorphic rocks, primarily gneiss and schist, some of the oldest visible bedrock in North America, dating back roughly 1.6 to 2.5 billion years. These crystalline formations resist erosion far better than the surrounding sedimentary layers, forcing the river into dramatic drops and rapids. As the river tumbles over these resistant outcrops, it reveals the violent geologic history of the region -- from the mountain-building uplifts of the Laramide Orogeny some 70 million years ago to glacial sculpting during the Pleistocene epoch.

On June 13, 1805, Lewis first heard the distant thunder of the falls and climbed a nearby ridge to glimpse the spectacle below. His journal captures both his awe and the scientific curiosity that drove the expedition: "The grandest spectacle I ever beheld," he wrote. This was no mere waterfall but a complex hydraulic system, with each cascade shaped by the alternating hardness of rock strata and the relentless current of the Missouri River, which drains an area of more than 500,000 square miles before joining the Mississippi.

Lewis was particularly intent on confirming their course. Before reaching the falls, uncertainty lingered whether they were navigating the Missouri River or its tributary, the Marias. The presence of these monumental falls verified that they were indeed on the correct river leading toward the Pacific. This confirmation was vital, since the expedition's purpose was to map and explore the newly acquired Louisiana Territory and find a practical route to the western ocean.

The falls themselves consist of five major cascades: the Black Eagle Falls, the Colter Falls (now submerged under a dam), the Rainbow Falls, the Crooked Falls (also submerged), and the Great Falls proper. The total elevation drop is approximately 612 feet, although early expedition measurements estimated more than 400 feet, a remarkable figure for this region of the Northern Plains. The river channel narrows and deepens sharply in places, creating turbulent waters filled with spray and mist, which would have made canoe travel impossible.

Faced with this obstacle, the expedition undertook one of the most arduous portages of their entire journey. For nearly a month, the men hauled their canoes, supplies, and baggage around the falls. They constructed crude wagons from the abundant cottonwood (Populus deltoides) trees lining the riverbanks. These wagons, essentially carts with wooden wheels, were fragile and often broke under the strain of heavy loads. The men dragged their gear across dry plains, navigating through dense patches of prickly pear cactus (Opuntia polyacantha) and avoiding venomous western rattlesnakes (Crotalus viridis). Sudden hailstorms and the relentless June heat added to their misery.

William Clark’s journal entry on July 3, 1805, conveys the physical toll: the men "hauled with all their strength, wate & art." This phrase captures the combination of brute force and ingenuity required to overcome the terrain. The portage route stretched roughly 18 miles from the foot of the falls to where the river became navigable again, a journey that taxed the expedition’s endurance as much as any battle or harsh winter.

The surrounding flora and fauna would have added texture to their experience. Along the riverbanks, stands of narrowleaf cottonwood and willow (Salix exigua) provided shade and materials for raft-building. The air carried the pungent scent of sagebrush (Artemisia tridentata) and the sharp tang of bitterroot (Lewisia rediviva), Montana’s state flower, blooming in the rocky soil. Birds such as the American dipper (Cinclus mexicanus) darted near the water’s edge, their calls mingling with the constant roar of the cascading falls.

Upon completing the portage, the expedition resumed their journey westward, following the Missouri River through the vast Northern Plains and eventually crossing the Rocky Mountains. But the Great Falls remained a landmark of immense significance, marking a boundary between the plains and the mountains and a test of the expedition’s resolve.

On their return trip in 1806, the expedition again encountered the Great Falls region. This time, Lewis separated from Clark at Travelers’ Rest near present-day Lolo, Montana, opting for a more direct route east through the Montana prairie. He passed near the Great Falls area once more before reuniting with Clark at the confluence of the Yellowstone and Missouri rivers. The memory of the falls and the hardships of the portage undoubtedly lingered as a vivid chapter of their expedition.

The Great Falls today lie beneath modern hydroelectric dams that harness the river’s energy, altering parts of the natural cascades. Yet the geological forces that shaped these falls remain legible in the landscape -- the resistant Precambrian bedrock, the sculpted river channels, and the wide valley carved by millennia of water flow. Standing near the falls, one can almost hear Lewis’s voice carried on the wind: "the grandest spectacle I ever beheld."

See also

• Lewis and Clark Passed Here at Great Falls, Cascade County
• Lewis and Clark Portage Route at Great Falls, Cascade County
• The Experiment at Great Falls, Cascade County