September 20, 1804 finds the expedition rounding the Grand Détour — the Big Bend of the Missouri — a thirty-mile river loop traversed by horse across a gorge barely a mile and a quarter wide. All five journalists are writing, and the day’s record is unusually layered: a geological observation from Lewis, a long pedestrian survey from Clark, a shared narrative spine from Gass and Whitehouse, and Ordway’s characteristic logistical precision. The day ends with the entire camp roused at one in the morning to flee a collapsing sandbar.
One Day, Two Geological Theories
The most striking convergence is geological. Lewis, writing one of his rare brief field notes, records a mineralogical curiosity at the bend’s commencement:
observed a clift of black porus rock which resembled Lava tho on a closer examination I believe it to be calcarious and an imperfect species of the French burr — preserved a specemine, it is a brownish white, or black or yellowish brown —
Lewis is doing scientific work — collecting, comparing to known European stone (the French burr millstone), correcting his initial impression. Gass, meanwhile, offers an entirely different geological argument about the same dark bluffs:
From these and others of the same kind the Missouri gets its muddy colour. The earth of which they are composed dissolves like sugar; every rain washes down great quantities of it, and the rapidity of the stream keeps it mixing and afloat in the water, until it reaches the mouth of the Mississippi.
Whitehouse reproduces this passage almost verbatim — “this Earth melts like Sugar” — a clear instance of the documented copying pattern between the enlisted journals, though here Whitehouse is tracking Gass’s phrasing rather than Ordway’s. Ordway, by contrast, notes only that the bluff carried “Some Salt peter on the Stones,” and Clark records that Newman and Thompson “picked up Some Salt mixed with the Sand” of a small run, comparable to what the Oto collected on the Corne de Cerf. Four narrators, four different mineral observations on the same stretch of bank.
Clark Alone on the Gorge
Clark’s entry is the day’s longest and most physical. He alone walked the neck of the bend and measured it: “the gorge of the Bend is 1 mile & a quarter (from river to river or) across,” rising to “high irregular hills of about 180 or 190 feet.” He alone records the prickly pear that “nearly ruind my feet” — a detail Ordway corroborates obliquely by naming a tributary “prickly pair creek.” And Clark alone supplies the day’s natural-history set piece: a careful description of the female pronghorn killed by Reuben Fields, distinguishing her from the male:
She Differs from the mail as to Size being Smaller, with Small Horns, Stright with a Small prong without any black about the neck — None of those Goats has any Beard, they are all Keenly made, and is butifull
Ordway notes the same kill but generalizes — “The She Goats have verry little horns, but are a handsome animal” — and adds the practical detail no one else records: “We Saved the Skins of the Goats and the Bones in order to Send back to the States next Spring.” The specimen-collection program of the expedition surfaces in Ordway’s logistics where Clark’s interest is anatomical and Lewis’s is mineralogical.
Clark also reports a hare that vanished into a hillside burrow — a sighting he records twice, in both his field notes and his fair copy, suggesting the animal puzzled him. Neither Lewis nor the enlisted journalists mention it.
The Midnight Sandbar
Three of the five accounts end with the same alarm. Gass:
At 1 o’clock at night, the bank where we were stationed began to fall so much, that we were obliged to rouse all hands, and go on a mile and cross the river before we could again encamp.
Ordway adds the swift current and the moon — “the moon Shined pleasant all night” — turning a logistical emergency into a small night-piece. Whitehouse follows Gass closely. Lewis and Clark, oddly, do not record the evacuation at all in the entries preserved here; Clark notes only that the party “Camped late on a Sand bar.” The pattern is instructive: the captains’ journals concentrate the day’s scientific and topographic observations, while the sergeants and privates preserve the embodied experience of the expedition — the prickly pear underfoot, the saved bones, the sandbar dissolving under sleeping men.
