The Great Falls According to Lewis

Great Falls 1880, Montana Historical Society

As Meriwether Lewis slowly traveled up the Missouri in June 1805, he was amazed to find not just one “great falls,” but a series of five falls of varying sizes.

The first falls he encountered would be what was named “Great Falls” in Clark’s maps. According to Paul Russell Cutright, in his book “Lewis & Clark, Pioneering Naturalists, “Lewis declared it to be the grandest sight he had ever beheld, the water of the Missouri here dropping over a precipice more than 80 feet high. He stood motionless for a long time, completely enchanted by the beauty of the scene.”

The measurements Lewis estimated were as follows:
Great Falls, 87 feet, ¾ inch
Crooked Falls, 19 feet
Rainbow Falls, 47 feet, 6 inches
Colter Falls, 6 feet, 7 inches
Black Eagle Falls, 26 feet, 5 inches

Great Falls 2019, NPS. 

William Clark, with his amazing accuracy, would re-measure each falls when he arrived a few days later.

Of course, as a visitor of this area today can attest, the beauty that Lewis experienced no longer exists, due to the hydro-electric dams built during the 20th century.