Circular 1246 

U.S. Department of the Interior 

U.S. Geological Survey 

Lewis and C{ark's 

Observations and Jvleasurentents of 

§eontoryho{ogy and J-fydro{ogy, 

and Changes with Tinte 

John A. Moody 

Robert H. Meade 

David R. Jones 

U.S. Department of the Interior 

U.S. Geological Survey 

Circular 1246 
U.S. DEPARTMENT OF THE INTERIOR 

Gale Norton 

Secretary 

U.S. GEOLOGICAL SURVEY 

Charles G. Groat 

Director 

Reston, Virginia 2003 

The use of firm, trade, and brand names in this report is 

for identification purposes only and does not constitute 

endorsement by the U.S. Government. 

Free on application to the 

U.S. Geological Survey 

Information Services 

Box 25286 

Denver, CO 80225-0286 

Library of Congress Cataloging-in-Publication Data 

Moody, John A. (John Alexander), 1944-

Lewis and Clark's observations and measurements of geomorphology and hydrology, and 

changes with time I John A. Moody, Robert H. Meade, David R. Jones. 

p. em. -- (U.S. Geological Survey circular ; 1246) 

Includes bibliographical references (p. ). 

1. Geomorphology--West (U.S.) 2. Landforms--West (U.S.) 3. Hydrology--West (U.S.) 

4. Lewis, Meriwether, 1774-1809--Diaries. 5. Clark, William, 1770-1838--Diaries. 6. 

Lewis and Clark Expedition (1804-1806) 7. West (U.S.)--Description and travel. I. 

Meade, Robert H., 1930- II. Jones, David R. (David Richard) III. Title, IV. Series. 

GB428.W38M66 2003 

551.41'0978--dc22 2003063132 
Ill 

Contents 

Foreword v 

Acknowledgments Vll 

I INTRODUCTION 1 

Meriwether Lewis 1 

William Clark 3 

Careful 0 bservers 3 

Itinerary 9 

Authors' Notes 9 

II GEOMORPHOLOGY 11 

Maps 11 

Meanders 15 

Landscapes 20 

Flood Plains and Terraces 31 

Channel-Scale Geomorphic Features 34 

Erosion, Sediment Transport, and 50 

Deposition 

III HYDROLOGY 63 

Runoff 63 

River Characteristics 70 

Hydraulic Geometry 75 

Velocity Measurements 79 

IV GEOMORPHIC AND HYDROLOGIC 

CHANGES IN 200 YEARS 85 

Glossary and Abbreviations 101 

Rivers, Creeks, and Sites (Map) 102-103 

References 105 
IV 

"Junction of the Yellowstone and the Missouri" painted by Karl Bodmer is based on 

a study done in 1833 and painted in Europe after his return from North America. 
:foreword 

THE ROOTS of the U.S. Geological Survey still thrive in the soil prepared two 

centuries ago by Lewis and Clark. The Lewis and Clark Expedition of 1803-06 

was, in the words of John Logan Allen (1975), " ... the first of what was to become 

a lengthy series of scientific explorations sponsored by the government of the 

United States ... [in which] trained and intelligent observers gathered and analyzed 

geographical information in what can only be described as a scientific method and 

documented the resulting geographical images fully in maps and regional descriptions." Notable successors to those first intrepid explorers were the railroad surveys that crossed the trans-Mississippi west at different latitudes before the Civil 

War. Then, after the war, came the western exploratory surveys led by Clarence 

King, Ferdinand Vandeveer Hayden, George Wheeler, and John Wesley Powell. 

Those four postwar surveys led directly to the creation in 1879 of a permanent 

government agency to continue to carry out the topographic, geologic, and hydrographic functions of those surveys of exploration-the U.S. Geological Survey. 

But making the connection between the Lewis and Clark Expedition and the 

present-day USGS is a deeper matter than the easy tracing of institutional genealogies. Even the casual reader of the scientific and engineering data collected and 

analyzed by Lewis and Clark will find in them the initial forays of the description 

and explanation of the topographic, geologic, hydrologic, and biologic characteristics of the landscape that have been the central thread of the work of the USGS 

for the past 124 years. The work of the modern USGS, like the work of Lewis and 

Clark, is motivated by the complementary goals of describing and understanding 

the physical world and providing a scientific basis for planning how society might 

best live in harmony with the land and its natural resources. 

This Circular expands on the rich descriptions of the hydrology and geomorphology-two sciences that had yet to be named 200 years ago-produced by Lewis 

and Clark. This Circular connects their work with 200 years of subsequent observation and knowledge produced by the USGS and other "trained and intelligent 

observers." Lewis and Clark provided the first major scientific documentation of 

the American West. The USGS scientists of today are proud to continue that tradition to explore, document, and explain the changing world around us. 

Robert M. Hirsch 

Associate Director for Water 

U.S. Geological Survey 

v 
VI 

Scale model of the keelboat (top) and red 

pirogue (bottom) used by Lewis and Clark. 
5\cknow {ecfgrnents 

ALL EXCERPTS in italics are from the University of Nebraska Press edition of The 

Journals of the Lewis and Clark Expedition edited by Gary E. Moulton and used by 

permission. Available wherever books are sold or from the University of Nebraska 

Press (800-526-2617) and on the Web at nebraskapress.unl.edu. Early stage data 

for the Ohio River at Louisville, Kentucky, were found by Steve Holmstrom of 

the U.S. Army Corps of Engineers. Photographic copies of the Bodmer paintings 

were provided by the Joslyn Art Museum, Omaha, Nebraska: gift of Enron Art 

Foundation, and copies of Clark's maps of the falls on the Columbia River were 

provided by the American Philosophical Society in Philadelphia, Pennsylvania. 

Early photographs of some sites on the Columbia River were provided by the U.S. 

Army Corps of Engineers, the Bonneville Power Administration, The University of 

Washington, and Washington State University. Other photographs were supplied 

by Bob Lindholm, Jim O'Connor, Norm Stucky, Lyn Topinka, Jim Wark, and Bill 

Woodcock. 

Mike Beckwith, Dale Blevins, Craig Brengle, Dan Driscoll, Tom Herrett, Robb 

Jacobson, David Kresch, Pat La Tour, Steve Lipscomb, Mary Kidd, Deborah Martin, 

Jim O'Connor, and J. Dungan Smith have been part of the volunteer corps helping 

to complete this Circular. They have reviewed parts of the manuscript, made significant suggested improvements, and sought out and found interesting details that 

have added to this story of Lewis and Clark. 

vii 
viii 

CONVERSIONS 

This Circular uses mostly English units. To determine equivalent 

metric values from English values, multiply the English values 

by the conversion factors listed below. To determine equivalent 

English values from metric values, divide the metric values by 

the conversion factors listed below. 

MEASUREMENT 

Length 

Area 

Volume 

Mass 

Force 

Volume per unit time (flow) 

Temperature 

Other units used by 

Lewis and Clark 

Vertical Datum 

MULTIPLY 

inch 

foot 

mile 

square foot 

square mile 

acre 

acre-foot 

cubic yard 

ounce 

pound 

slug 

foot per second 

cubic foot per second 

degree Fahrenheit 

bushel 

link 

pole 

pole 

chain ( 4-pole) 

rod 

rod 

league 

fathom 

yard 

BY 

25.4 

0.3048 

1.609 

0.09290 

2.590 

0.4047 

1,233 

0.7645 

28.35 

0.4536 

0.132 

0.3048 

0.02832 

°F-32 

1.8 

2,150.42 

7.92 

16.5 

25 

66 

16.5 

100 

3 

6 

3 

TO OBTAIN 

millimeter 

meter 

kilometer 

square meter 

square kilometer 

hectare 

cubic meter 

cubic meter 

gram 

kilogram 

newton 

meter per second 

cubic meter per second 

degree Celsius 

cubic inch (in3) 

inch (in) 

foot (ft) 

link 

foot (ft) 

foot (ft) 

link 

mile (mi) 

foot (ft) 

foot (ft) 

In this report, "sea level" refers to the National Geodetic Vertical Datum 

of 1929 (NGVD of 1929)-a geodetic datum derived from a general 

adjustment of the first-order level nets of both the United States and 

Canada, formerly called "Sea Level Datum of 1929." "Mean sea level" 

is not used with reference to any particular vertical datum; where used, 

the phrase means the average surface of the ocean as determined by 

calibration of measurements at tidal stations. 
I 

Introduction 

ffwo VERY different men, Meriwether Lewis and William Clark, joined to 

J, ~ake the first recorded set of scientific observations and measurements of 

geomorphology and hydrology west of the Mississippi River. They did not limit 

themselves to these two scientific topics but were true naturalists, making observations and measurements related to astronomy (Large, 1979; Bedini, 1984; 

Plamondon, 1991; Bergantino, 1998), biology (Cutright, 1969), ecology, ethnology 

(Ronda, 1984a), geology (Bluemle, 2001; Bergantino, 1998), and phenology, as 

well as to the general geographical understanding of the arrangements of rivers 

and other topographical features of the trans-Mississippi West (Allen, 1975) . 

.Jvt.eriwetlier Lewis 

Meriwether Lewis was born near Charlottesville, Virginia, on August 18, 1774. 

He was the expedition's biologist and botanist. His journal entries are the more 

descriptive and narrative and can often transport the modern reader back in time. 

An excerpt from Lewis's journal entry describing the White Cliffs area of the 

Missouri Breaks (page 89, bottom left) in Montana illustrates his writing style: 

... The hills and river Clifts which we passed today exhibit a most romantic 

appearance. The bluffs of the river rise to the hight of from 2 to 300 feet and 

in most places nearly perpendicular; they are formed of remarkable white 

sandstone which is sufficiently soft to give way readily to the impression of 

water; two or thre thin horizontal stratas of white free-stone, on which the 

rains or water make no impression, lie imbeded in these clifts of soft stone ~ ~ 

near the upper part of them ... The water in the course of time in decending 

from those hills and plains on either side of the river has trickled down the 

soft sand clifts and woarn it into a thousand grotesque figures, which with 

the help of a little immagination and an oblique view at a distance, are 

made to represent eligant ranges of lofty freestone buildings, having their 

parapets well stocked with statuary; collumns of various sculpture both 

grooved and plain, are also seen supporting long galleries in front of those 

buildings; in other places on a much nearer approach and with the help of 

less immagination we see the remains or ruins of eligant buildings; some 
2 Lewis and Clark's Observations and Measurements of Geomorphology and Hydrology, and Changes with Time 

collumns standing and almost entire with their pedestals and capitals; others 

retaining their pedestals but deprived by time or accident of their capitals, 

some lying prostrate an broken othes in the form of vast pyramids of connie 

structure bearing a sereis of other pyramids on their tops becoming less as they 

ascend and finally terminating in a sharp point ... As we passed on it seemed 

as if those seens of visionary inchantment would never have and end; for here 

it is too that nature presents to the view of the traveler vast ranges of walls of 

tolerable workmanship, so perfect indeed are those walls that I should have 

thought that nature had attempted here to rival the human art of masonry 

had I not recollected that she had first began her work .. .31 May 1805 

Of this remarkable passage, J.L. Allen (1975, p. 268) wrote: "Lewis's prose was 

worthy of the landscape; never has a better description of the Breaks and their glory 

been penned. And not until John Wesley Powell, more than a half-century later, 

made his celebrated first trip down the Colorado River would any observer come 

so close to describing the landforming processes so characteristic of arid environments." Two weeks later, Lewis described the Great Falls of the Missouri: 

... a smoth even sheet of water falling over a precipice of at least eighty feet, the 

remaining part of about 200 yards on my right formes the grandest sight I 

ever beheld, the hight of the fall is the same of the other but the irregular and 

somewhat projecting rocks below receives the water in it's passage down 

and brakes it into a perfect white foam which assumes a thousand forms in a 

moment sometimes flying up in jets of sparkling foam to the hight of fifteen 

or twenty feet and are scarcely formed before large roling bodies of the same 

beaten and foaming water is thrown over and conceals them. in short the 

rocks seem to be most happily fixed to present a sheet of the whitest beaten 

froath for 200 yards in length and about 80 feet perpendicular. the water 

after decending strikes against the hutment before mentioned or that on 

which I stand and seems to reverberate and being met by the more impetuous 

courant they role and swell into half formed billows of great hight which rise 

and again disappear in an instant ... 13 June 1805 

However, Lewis was not pleased and later wrote on that same day: 

... after wrighting this imperfect discription I again viewed the falls and was so 

much disgusted with the imperfect idea which it conveyed of the scene that I 

determined to draw my pen across it and begin agin, but then reflected that 

I could not perhaps succeed better than pening the first impressions of the 

mind; I wished for the pencil of Salvator Rosa or the pen of Thompson, that 

I might be enabled to give to the enlightened world some just idea of this 

truly magnifficent and sublimely grand object ... 13 June 1805 
Introduction 

Wi[fiam C[ark 

William Clark was born near Charlottesville, Virginia, on August 1, 1770. He was 

the expedition's cartographer and riverman. His journal entries, while complete, 

are often brief and present only the necessary facts. His style makes for entertaining reading because his journal entries use many abbreviations (see Glossary) 

and have novel punctuation and spellings. A word is often spelled several ways but 

each is phonetically correct. He characteristically spells "very" with two r's. Clark 

appears to capitalize those words he wants to emphasize. Clark wrote in 1804 

below the Kansas River: 

... rain last night after fixing the new Oars and makeing all necessary 

arrangements, we Set out under a jentle breese from the S. E. and proceeded 

on passed two large Islands on the S.S. leaving]. Shields and one man to 

go by land with the horses Some verry hard water, passed Several Islands 

& Sand bars to day at the head of one we were obliged to cleare away 

Driftwood to pass, passed a Creek on the L. Side Called <Tabboe> 15yds. 

wide passed a large Creek at the head of an Island Called Tiger River on the 

S. S. The Island below this Is d. is large and Called the Isle of Panters, formed 

on the S.S. by a narrow Channel, I observed on the Shore Goose & Rasp 

berries in abundance in passing Some hard water round a Point of rocks on 

the L. S. we were obliged to take out the roape & Draw up the Boat for 112 

a mile, we Came too on the L.S. near a Lake of the Sircumfrance of Several 

miles, Situated on the L.S. about two miles from the river ... 19 June 1804 

Careju[ Observers 

The observations made by Lewis and Clark were mostly localized in time and 

space to the narrow river corridors they were traversing on any given day. 

However, based on these local observations, they frequently commented on the 

potential future uses of the land and rivers and made remarkably prescient and 

insightful conjectures, inferences, and conclusions about the character of the land 

beyond the immediate river corridors. Their visions of the potential uses of various 

lands were influenced by the agrarian character of America at that time and by the 

heavy dependence upon rivers for energy and transportation. Comments on actual 

and potential land use were common in the journal entries during the period when 

Lewis and Clark were laboring upriver against the Missouri River current through 

what are now the States of Missouri, Iowa, and Nebraska. Clark wrote near the 

Chariton River between Jefferson City and Kansas City, Missouri: 

... Some high land which has a great quantity of Stone Calculated for 

whetstons ... I walked out three miles, found the prarie composed of good 

3 
4 Lewis and Clark's Observations and Measurements of Geomorphology and Hydrology, and Changes with Time 

Land and plenty of water roleing & interspursed with points of timberd land, 

Those Praries are not like those, or a number of those E. of the Mississippi 

Void of every thing except grass, they abound with Hasel Grapes & a wild 

plumb of a Superior quallity, called the Osages Plumb ... 1 0 June 1804 

Later, farther up the Missouri, Lewis and Clark noted potential industrial use on 

the Platte River in northwestern Missouri . 

... passd the (1) mouth of a Small river 10 ms above the Kanseis Called by 

the french Petite River Platte (or Shoal river) from the number of falls in 

it, this river is about 60 yards wide at its mouth and runs Parrilel with the 

Missouries for ten or twelve miles, told that the lands on this Small river is 

good, and on its Several falls well Calculated for mills .. .30 June 1804 

Observations made by Lewis and Clark were localized to the narrow river corridors they were 

traversing (orange). They also could extrapolate their 

vision of the nature of the land beyond the narrow 

river corridors to the interior of each river basin. 

/Marias 

• 

I WHITE CLIFFS OF THE 

I MISSOURI BREAKS 

Grear Falls 

Bazile/ 
Introduction 

In retrospect, however, this Platte River (not the Platte River in Nebraska) was not 

suitable for mills. It is a slow and meandering river with very few and small riffles 

(Dale Blevins, oral communication, 2002). Bazile Creek in northeastern Nebraska 

was also noted for potential industrial uses: 

... possesses many excellent situations for grist mills and other waterworks ... Fort 

Mandan Miscellany, Moulton, 1987, v. 3, p. 356. 

They even noted potential construction materials a few miles north of what is now 

Omaha, Nebraska, and at the mouth of the Cheyenne River in South Dakota: 

... The Situation of this place which we Call Council Bluff which is handsom 

ellevated a Spot well Calculated for a Tradeing establishment, the Bank 

high & leave! on top well Calculated for a fort ... those Bluffs afford good 

Clay for Brick, a great quantity of the 3 points one Opsd. one abov & one 

below . .3 August 1804 

... large quantities of tar may be procured on the river near the Black hills, and 

may be readily brought down the river. tar and sand in the proportion of one 

gallon to the Bushel, make a furm and strong cement. if an establishment 

is made at this place, the work must of necessity be principally formed 

of brick; there being no stone and but little timber. the drift-wood of the 

Missouri will supply an ample quantity of fuell ... Fort Mandan Miscellany, 

Moulton, 1987, v. 3, p. 360. 

Not only did Lewis and Clark predict potential uses in the future, but they 

"saw" far into the interior of the Louisiana Purchase. Their continuing ability 

to extrapolate their vision of the nature of the land beyond the narrow river 

corridors was essential to the success of the expedition. During their 

upriver traverse, on Monday, June 3, 1805, the expedition 

~ / 

-;;.· 1 V> 

~· 

<1" 

.ro . 

:6 

.6_,.. 

~~' ~ DUBOIS 

was faced with deciding which of two forks was 

\l"-0 

0 • Louisville 

5 
6 

Science in 1800: Historical Context 

When Thomas Jefferson was Minister to 

France and lived in Paris from 1785 to 1790, 

he probably found opportunities to inform 

himself about the new ideas relative to the 

earth sciences that were emerging in the scientific centers of Europe. We can surmise also 

that, following his return to Virginia and his 

ascendancy to the Presidency, he discussed at 

least some of these new ideas with Meriwether 

Lewis before the expedition began. Severi l 

decades earlier, Paolo Frisi had published his 

"Treatise on Rivers and Torrents with Methods of Regulating their Courses and Channels" 

(Frisi, 1762). Although Frisi's treatise was not 

translated from Italian to English until 1818, 

Jefferson, with his facility in Latin and Italian, 

would have been able to read it if it had come 

to his attention. The late 1700s also saw the 

beginnings of the great revolution of geologic 

thought that would culminate in 1830 in Sir 

Charles Lyell's "The Principles of Geology." 

James Hutton, the Scottish geologist who is 

considered the father of uniformitarianism, 

had laid the foundations, in his 1785 book, for 

the notion that the present is the key to the past 

and that earth surface processes operated in a 

slow but continuous manner. But it was not 

until 1802, when John Playfair published his 

"Illustrations of the Huttonian Theory of the 

Earth," that these ideas began to reach a wide 

audience. As counterpoint to the uniformitarian ideas that were emerging in Great Britain 

at the end of the 18th century, others had proposed a form of catastrophism stemming from 

the Biblical Flood but expanded to include 

ordinary floods, wildfires, volcanic eruptions, 

and earthquakes as explanations of some 

earth-surface processes. Principal among the 

proponents of catastrophism were Abraham 

Gottlob Werner and, during his earlier years 

of scientific endeavor, Professor Werner's most 

illustrious student, Alexander von Humboldt, 

who pioneered land-based exploration with a 

scientific bent (Tinkler, 1985). 

-·-Lewis and Clark's was therefore not the only 

scientific expedition into unmapped territory 

during the years that opened the 19th century. 

Baron Alexander von Humboldt and his colleague Aime Bonpland had been exploring 

the "equinoctal regions" of South America, 

beginning in 1799, and had been accumulating, 

along with those of plants and animals, observations of hydrologic phenomena, including 

the navigable connection between the headwaters of the Amazon and Orinoco Rivers in what 

is now southernmost Venezuela. It is doubtful, 

however, whether significant news of any of 

Humboldt's observations had reached North 

America by the time Lewis and Clark departed 

for the western rivers. 

Whether the ideas of Frisi, Hutton, Playfair, 

Werner, von Humboldt, and other European 

earth scientists had come to America in time for 

Lewis and Clark to carry them across the continent and incorporate them into the underlying 

assumptions of their journal writings is not 

entirely clear. From reading the journals, we 

are inclined to suggest that most of Lewis and 

Clark's hydrologic and geomorphologic observations were too original and too motivated by 

practical matters to have been much encumbered by the more theoretical concerns and 

controversies that were being aired elsewhere 

in the scientific world of the early 1800s. There 

is no doubt, however, that the explorations of 

Lewis and Clark were an enormous source of 

inspiration to later efforts by others-most 

directly and notably, to the exploration of the 

peoples and landscapes of the Missouri River 

30 years later by the Prussian prince, Maximilian von Wied, and the Swiss artist, Karl Bodmer 

(Thwaites, 1966). Somewhat farther removed 

in space and time, but also clearly inspired by 

Lewis and Clark, was the exploration of the 

Amazon River valley made 50 years later by 

U.S. Naval Lieutenant William Lewis Herndon 

(Herndon, 1853). 
Introduction 

the Missouri River (one was the Missouri River; the other one was later named 

the Marias River). This was a critical decision. Choosing the correct fork would 

lead them to the Great Falls and a possible route through the Rocky Mountains 

to the Columbia River and the Pacific Ocean. Lewis wrote: 

... An interesting question was now to be determined; which of these rivers 

was the Missouri, ... to this end an investigation of both streams was the 

first thing to be done; to learn their widths, debths, comparitive rappidity 

of their courants and thence the comparitive bodies of water furnished by 

each ... The noth fork is deeper than the other 

but it's courant not so swift; it's waters run 

in the same boiling and roling manner which 

has uniformly characterized the Missouri 

throughout it's whole course so far; it's 

waters are of a whitish brown colour very 

thick and terbid, also characteristic of the 

Missouri; while the South fork is perfectly 

transparent runds very rappid but with a smoth unriffled surface it's bottom 

composed of round and flat smooth stones like most rivers issuing from a 

mountainous country. the bed of the N . fork composed of some gravel but 

principally mud; in short the air & character of this river is so precisely that 

of the missouri below that the party with very few exceptions have already 

pronounced the N. fork to be the Missouri; myself and Capt. C. not quite 

so precipitate have not yet decided but if we were to give our opinions I 

believe we should be in the minority, certain it is that the North fork gives 

the colouring matter and character which is retained from hence to the gulph 

of Mexico. I am confident that this river rises in and passes a great distance 

through an open plain country I expect that it has some of it's sauces on 

the Eastern side of the rocky mountain South of the Saskashawan, but that 

it dose not penetrate the first range of these Mountains and that much the 

greater part of it's sources are in a northwardly direction towards the lower 

and middle parts of the Saskashawan in the open plains. convinced I am that 

if it penetrated the Rocky Mountains to any great distance it's waters would 

be clearer unless it should run an immence distance indeed after leaving those 

mountains through these level plains in order to acquire it's turbid hue ... thus 

have our cogitating faculties been busily employed all day .. .3 June 1805 

After crossing the Continental Divide, the expedition was in the vicinity of Missoula, 

Montana, and contemplating the Clark Fork as a possible route to the Columbia 

because the Snake River route was impassable. Lewis again extrapolates beyond his 

immediate observations to deduce that the Clark Fork would also be impassable: 

... it is hear a handsome stream about 100 yards wide and affords a considerable 

quantity of very clear water, the banks are low and it's bed entirely gravel. the 

7 

Confluence of the Marias 

(left) and Missouri (right) 

rivers looking downstream. 

Photo: Montana Tourism 
8 Lewis and Clark's Observations and Measurements of Geomorphology and Hydrology, and Changes with Time 

stream appears navigable, but from the circumstance of their being no sammon in 

it I believe that there must be a considerable fall in it below ... 9 September 1805 

Their prediction was confirmed 5 months later while interviewing native people at 

Fort Clatsop near the mouth of the Columbia River. Clark's version is given here: 

... from the same information [Indians] Clarks river [Clarks Fork] like that 

of the S. E. branch of the Columbia [Snake River?] which heads with 

Jefferson's and Maddisons river's can not be navagated thro' the rocky 

mountains in consequence of falls and rapids and as a confirmation of the 

fact we discovered that there were no Salmon in Clark's river, which is not 

[Lewis' version does not have this "not"] the Case in the S. E. branch of the 

Columbia altho it is not navagable. added to this, the Indians of different 

quartes further inform us, that Clark's river runs in the direction of the 

Rocky Mountains for a great distance to the north before it discharges 

itself into the Columbia river- . from the Same information the Columbia 

from the enterance of the S. E. branch to the enterance of Clark's river is 

obstructed with a great number of dificuelt and dangerous rapids (and the 

place Clark's river comes out of the Rocky mountains is a tremendious falls 

&c which there is no possibillity of passing the mountains either by land or 

water.) ... 14 February 1806 

and again later on the return trip in 1806 near Lewiston, Idaho, on the Clearwater 

River: 

... at this place we met with three men of a nation called the Skeets-so-mish 

who reside at the falls of a large river disharging itself into the Columbia 

on it's East side to the North of the entrance of Clark's river. this river they 

informed us headed in a large lake in the mountains and that the falls below 

which they resided was at no great distance from the lake ... 6 May 1806 

The large river was the Clark Fork, which flows into the northeast corner of Lake 

Pend Oreille and becomes the Pend Oreille River as it leaves the lake. The falls were 

probably the Albeni Falls at the northwest end of Lake Pend Oreille. These falls are 

only about 8 feet high (Craig Brengle, written communication, 2002), and unless 

the salmon arrived at low water in the fall, it is unclear if this height would halt the 

runs of salmon and steelhead so effectively that neither species is found in the Clark 

Fork. However, the native people may have had in mind the larger Post Falls on the 

Spokane River at the outlet of Coeur d'Alene Lake only 50 miles to the south-or 

perhaps other potential barriers, located downstream from Albeni Falls at Kettle 

Falls on the Columbia River, at Z Canyon on the Pend Oreille River at the boundary 

between Washington and British Columbia, or at Box Canyon and Metaline Falls 

in Washington (all under reservoirs now) (Mike Beckwith, written communication, 

2002).' After recrossing the Continental Divide, the expedition divided into two 
Introduction 

groups. Clark's group explored the Yellowstone River in July 1806 while Lewis's 

group explored the Marias River. Here Clark made another extrapolation: 

... Tongue River it dicharges itself on the Star d. Side and is 15 0 yards wide of 

water the banks are much wider .... but finding that its' water So muddy and 

worm as to render it very disagreeable to drink ... The water of this river is 

nearly milk worm very muddy and of a lightish brown Colour .... ! believe 

that the Country back thro' which this river passes is an open one where the 

water is exposed to the Sun which heats it in its passage ... 29 July 1806 

Itinerary 

Lewis started down the Ohio River in August 1803 and met Clark near Louisville 

(in what is now Kentucky) in October 1803. Together, they continued down the 

Ohio and traveled up the Mississippi River to St. Louis (pages 4 and 5). Their expedition spent the winter of 1803-04 at Camp Dubois opposite the mouth of the 

Missouri River. They started up the Missouri River on May 14, 1804, and reached 

the Mandan village near the present city of Bismarck, North Dakota, in October 

1804; there they spent the winter of 1804-05. During 1805, they "proceeded 

on," circumvented the Great Falls of the Missouri and then crossed, recrossed, 

and again crossed the Continental Divide, searching and eventually finding a route 

to the Pacific. The winter of 1805-06 was spent near the mouth of the Columbia 

River at Fort Clatsop. They returned in 1806 but spent several months at Camp 

Chopunnish, waiting for the snow to melt before they could cross the Rocky 

Mountains. The expedition arrived back in St. Louis on September 23, 1806 . 

.Jl..utfiors' :Notes 

Thomas Jefferson conceived the idea of a scientific expedition of discovery, gave 

Lewis and Clark detailed instructions regarding scientific observation, and was 

essentially the third person commanding the Corps of Discovery (page 6, "Science 

in 1800"). The scientific observations of Lewis and Clark in this circular are not 

organized in chronological order but by two major topics-geomorphology and 

hydrology. The regional-scale geomorphic features are reflected in their maps and 

descriptions of the surrounding landscapes. Valley-scale features are flood plains 

and terraces. The channel-scale features are riffles, rapids, falls, and sandbars. The 

"Geomorphology" section ends with Lewis and Clark's observations of erosion, 

sediment transport, and deposition processes that change the river and the landscape. The "Hydrology" section begins with observations of the runoff processes. 

Runoff determines river characteristics, hydraulic geometry, and river velocities. 

The final section summarizes the changes that have occurred in the 200 years since 

the Lewis and Clark expedition. 

9 
10 Lewis and Clark's Observarions and Measurements of Geomorphology and Hydrology, and Changes wirh Time 

All excerpts (italics) in this Circular have been taken from Moulton's (1983-93) 

eight annotated volumes of the Journals of Lewis and Clark. The journals include 

their maps, field notes, and numerous codices as well as personal journals. The 

excerpts are included verbatim such that punctuation, spelling, and capitalization 

are those of Lewis and Clark. Material inserted by Moulton is indicated by [] 

with the text in an italic font. Material inserted by the authors of this Circular is 

indicated by [] but with the text not italicized. Material inserted by other editors 

is indicated by <> and is in italics. The date of each excerpt is given in the form 

18 June 1804 to be consistent with the form most often used by Lewis and Clark. 

Often, they repeated each other's entries or made similar entries in both their individual journals as well as in field notes. However, usually each entry can be identified by the distinctly personal style of each writer. 

In March of 1803 cartographer Nicholas King was commissioned to prepare a map of the West using the most 

current cartographic sources. Notes on the map by Lewis suggest that it was probably carried by the expedition. 

Notice the large blank (unmapped) area between the Pacific coastline (left) and Great Lakes (right). 
II 

(jeomorylio[ogy 

L EWIS and Clark provided some of the first descriptions of flood plains and 

other geomorphic features in the United States and how these features were 

altered by erosion, sediment transport, and deposition. One primary geomorphologic contribution was the creation of detailed maps that Lewis and Clark made 

of the network of rivers and landforms. Adjectives they used to describe the landforms they encountered, traversing several physiographic provinces, are found 

today in the standard names of the subdivisions of these provinces. 

:Jvlays 

Clark made the first accurate maps of the rivers adjacent to their route and of 

the surrounding country. These maps (Moulton, 1983, volume 1) were based not 

only on personal observations and measurements but also on extensive discussions 

with the native people (Ronda, 1984). During the winter of 1804-05, while at 

Fort Mandan near the present town of Bismarck, North Dakota, Lewis and Clark 

wrote "A Summary view of the River and Creeks ... " and in it Lewis mentions the 

method of obtaining information: 

... As we have only ascended the Missouri, a few miles above the Mouth of 

Knife river, the subsequent discription of this river, and it's subsidiary streams 

are taken altogether from Indian Information. the existence of these rivers, 

their connection with each other, and their relative positions with rispect to 

the Missouri, I conceive are entitled to some confidence. information has 

been obtained on this subject, in the course of the winter, from a number of 

individuals, questioned seperately and at different times. the information 

thus obtained has been carefully compared, and those points only, in which 

they generally agreed, have been retained, their distances they give, by 

days travel, which we have estimated at 25 miles pr. day ... Fort Mandan 

Miscellany, Moulton, 1987, v. 3, p. 362. 

Clark was the expedition's cartographer. He carefully recorded the magnetic compass bearing for each reach of river and the length of each reach traversed during 

the day (page 13 ). While descending the Ohio River, he stopped and mapped the 

confluence with the Mississippi River in November of 1803. He measured the 

magnetic compass bearing of the Mississippi River shoreline (S 74o W) and the 

AUTHORS' NOTE 

The place names mentioned in this section 

can be found on the map on pages 102-103. 

Lewis and Clark prepared 

maps daily such as this 

one of the Great Falls in 

Montana. Notice the detailed 

notation along the river. 

Smithsonian 
12 

Instruments used to Measure Distance, Heights, and Angles 

This is a brief description of some of Lewis and Clark's instruments used to measure distance, heights, and angles. Lewis gives A summary discription of the apparatus employed 

... some remarks on the manner in which they have been employed ... 22 July 1804. 

*Circular protractor and index for measuring and plotting angles on paper. 

* Circumferentor is a magnetic compass that measures the horizontal angle between 

magnetic north and a landmark. 

* Logline and reel. At the end of the line was a log or flat, triangular piece of wood 

weighted along one edge so that it would be partially submerged in the water. A bridle 

of three short lines connected each corner of the wood log to the line. Knots were tied 

in the line or attached to the line like an appendage, at intervals of 7 fathoms. The line 

was wound around a reel. The log was cast over the side into the water and the line 

was pulled off the reel by the motion of the boat moving relative to still water. Similarly, if the boat was anchored in a river, then the water moving downstream pulled 

the line off the reel. By counting the number of knots that came off the reel during a 

specific time, the speed of the boat or the speed of the water could be calculated. 

* Pocket compass is a small version of the circumferentor. 

William Clark's pocket 

compass and case 

Smithsonian 

* Spirit level is similar to present-day carpenter levels with a bubble of air trapped in a 

tube of liquid to determine when a su face is horizontal. 

*Two-pole chain consisted of 50 links. Each link was 7.92 inches long so that the twopole chain was 33 feet long. 

A more detailed discussion, especially of the astronomical instruments, has been 

published by Bedini (1984) and Plamondon (1991). 
Geomorphology 

IS 

"r" 

i, --$ 

g i 

Course and distance on e Missouri River for September II, 1804 

Bearing Distance Comments 

(miles) 

4112 mes. To the lower pt of an Island, passed the Isd. On which we Campd 

2 mes. To the. head of the Island on its L.S. 

N.45°W J -mes. To a pt. On the L.S. below an Island (1 ) 

N.50°W 2 mes. To the upper pt of an Island on the S.S. passed one on the L.S. 

opsd. To which at 114 of a mile is a Village of the Barking Squire/ L. S. 

West 4 112 ·mes. To a pt. On the S.S. Passed an Isd. On the S.S. just above the one 

mentioned in the last Course. 11th 

16 Source: Moulton, 1987, p. 65, volume 3 

bearing of the Ohio River shoreline (N 52 1/2° W) where they meet at the confluence point by using the Circumferenter . 

... A Circumferentor, circle 6 Inches diameter, on the common construction; 

by means of this instrument adjusted with the sperit level, I have taken the 

magnetic azimuth of the sun and pole Star. It has also been employed in 

taking the traverse of the river ... 22 july 1804 

His measurement of the angle between these shorelines at the confluence was 

therefore 53.5°. The present-day magnetic bearings of the shorelines measured 

from the 1978 version of the U.S. Geological Survey's 7.5-minute quadrangle 

(Wyatt Quadrangle) are N 52oW and S 77.5 °W. The angle between the shorelines 

at the confluence point is 50.5°. Clark established a baseline along both shores 

starting at the confluence point or vertex of the angle. He may have measured the 

length of the baseline by using a cased measuring tape (Bedini, 1984) but probably 

used a surveyor's chain consisting of 100 metal links and equal to 66 feet. He probably did not use the chain to measure distance across rivers as wide as the Ohio 

13 
14 Lewis and Clark's Observations and Measurements of Geomorphology and Hydrology, and Changes with Time 

Missouri River 

Commission distances, 

in miles 

10,000 Mouth of the Mtssourz R. to Grasshopper Cr. 

REACH LENGTHS 

• Mouth of the Missouri to just 

above the Great Falls 

• Canyons above the Great Falls 

Comparison of the lengths of 

various reaches measured by 

Lewis and Clark in 1803-04 with 

those measured by the Missouri 

River Commission between 

1892 and 1895 before major 

changes. A log-log graph shows 

differences of both the short 

and long reaches. The inset 

shows in more detail the reach 

lengths above the Great Falls. 

1000 

100 

10 

James R. to Ltttle Missourz R. • Unconfined areas above 

I 

the Great Falls 

Mouth of the Mzssourz R. to Kansas R. 

Ltttle Mtssourz R. to Yellowstone R. l • Mlssoun River 

~ Comm1ssion d1stances, 

i;/ 

·-· .,)~· 

,------:.=-"-, r.. , ~ 

. -~· ' 

• f 

in miles 

40 

20 

0 

--• 0 20 40 

• Lewis and Clark distances, 

in miles 

10 100 1000 10,000 

Lewis and Clark distances, in miles 

and Mississippi Rivers. Clark could have determined the width across a river by 

first drawing a map showing the baseline and two angles or bearings measured at 

either end of the baseline to a landmark on the opposite side of a river and then 

measuring the width of the river on his map. The baseline along the Ohio River 

was 115 poor 1,897.5 feet long, and the baseline along the Mississippi River was 

117 poor 1,930.5 feet long . 

... asscertained by the Circumferenter and projection that the width of the Ohio 

from the point [confluence point] was- 1274 Yards [and] The Missippi-

[was]1435 Yards and the width of them both from those observed points on 

their respective banks was- 2002 Yards ... 14 November 1803 

One way to assess the accuracy of Clark's river distances is to compare them 

with those measured from the maps published by the Missouri River Commission 

(1892-95) and based on some topography as early as 1878. We compared the length 

of a number of unconfined reaches of the Missouri River between the Great Falls 

and the Mississippi River (figure above). Some differences in reach lengths between 

1803-05 and 1892-95 may be explained by geomorphic processes like meander 

cutoffs. A part of the Missouri River in what is now western Montana passes 

through a landscape alternating from unconfined rolling prairie reaches near Great 

Falls to stable canyon reaches near the Gates of the Rockies (now the site of Canyon 

Ferry Reservoir) to unconfined reaches and back to canyon reaches near Three 

Forks, Montana, where the Jefferson, Madison, and Gallatin Rivers join to form the 

Missouri River. Distances within the stable canyon reaches (smaller graph, above) 
Geomorphology 

should change very little as a result of geomorphic processes during the intervening 

90 years between Clark's measurements and the surveys done by the Missouri River 

Commission (MRC) between 1892 and 1895. For eight canyon reaches ranging 

in length from about 3 to 50 miles, the average difference (MRC's- Clark's) was 

-1.1 mile, or a 6.9-percent difference. For four unconfined reaches ranging in 

length from about 12 to 45 miles, where changes would more likely be a result 

of geomorphic processes, the average difference was -8.0 miles. This shortening 

may represent cutoffs during the intervening 90 years. Clark's total river distance 

(3,064 miles) from the mouth of the Missouri near St. Louis, Missouri, to Willards 

Creek (now Grasshopper Creek, p. 102, v. 5, Moulton, 1988), where the expedition ended their travel by water, is 649 miles longer than the distance measured on 

maps in 1998. 

:M.eanders 

Meandering rivers do not stay the same length. They become longer in some 

reaches as meanders grow larger across the meander belt (following page, "River 

Terms" ). They become shorter in other reaches as chutes cut across meander bends 

to eventually become the main channel while isolating the old meander bends as 

oxbow lakes. The first observations of meanders were recorded in the Lewis and 

Clark journals during their descent of the Ohio River in the fall of 1803 at a time of 

unusually low water. Lewis comments after having pulled the boat over a riffle near 

what is now Ambridge, Beaver County, Pennsylvania (p. 69, v. 2, Moulton, 1986) 

... The hills on either side of the ohio are from 3 to 400 feet which runing 

parrallel to each other keep the general course of the river, at the distance of 

about two miles while the river pursuing a serpentine course between them 

alternately washes their bases ... thus leaving fine bottom land between itself 

and the hills in large boddys, and freequently in the form of a simecicles or 

the larger segment of a circle or horseshoe form ... 2 September 1803 

Clark recognized oxbow lakes in Missouri above Kansas City that were once river 

meanders: 

... a large Lake on the S. S. which has the apperance of being once the bed of 

the river & reaches parrelel for Several Miles .. A July 1804 

... I neglected to mention yesterday that the Lake on the S. S. was large Say 314 

me. wide & 7 or 8 long ... S July 1804 

Later, on the Missouri River about 100 miles above the Platte River in Nebraska, 

Clark made additional observations: 

... I have observed a number of places where the River has anced run and 

now filled or filling up & growing with willows & cottonwood) ... (! have 

15 
16 

River Terms 

*Alluvium is any material ranging in size from clay to gravel that is eroded, transported, and deposited by a river to form its channel and flood plain. 

*Bankfull refers to the water level that corresponds to the tops of the riverbanks. 

Discharge at bankfull level (one of many possibilities) is thought to be important in 

determining the geometry of a river channel. Bankfull conditions, on average, can 

be expected to be reached or exceeded about 2 of every 3 years or about every 1.5 

years (Leopold and others, 1964). f 

*Braided rivers have many shifting channels, and the slopes are steeper than the 

slopes of meandering rivers. See the multiple channels between sandbars and 

islands in Clark's maps on page 13 and 18. 

*Chute is a new channel that forms across the base of a meander. As it grows in size, 

it carries more of the flow. 

* Crossing is the transitional area between bends of a river where the deep part of 

the channel switches from one side of the river to the other side. Sometimes called 

a riffle (page 36, "Riffle Formation"). 

*Cutbank is a steep vertical bank, usually actively eroding at its base (page 36, "Riffle Formation"). 

* Discharge is the volume of water passing a point on the river during a specific 

period of time. It is usually expressed in cubic feet per second in the United States. 

* Flood plain is the relatively flat area adjacent to the river that is shaped by the erosion and deposition of sediment during floods. 

*Meander is a single, S-shaped channel pattern formed in alluvial material. 

*Meander belt is the area between the bdges of the valley that is sculpted by the river 

moving laterally, with time, across the flood plain. 

* Meander scroll is a sediment formation made by deposition along a former channel 

boundary. 

*Natural levee is formed when the river overflows the top of the bank, the water I 

velocity decreases, and coarse material drops out of suspension along the bank to 

form a ridge. 

*Oxbow is created after a chute cuts across a tight meander bend, leaving the old 

channel (oxbow) only partially connected to the new one (Riffle Formation, page 36). 

* Oxbow lake is a lake that has formed by sediment filling in both ends of an ox 

bow. This prevents the oxbow lake from having a direct surface connection with 

the main channel during normal in-channel flows. 

* Point bar is a sloping bank consisting of sand or gravel on the inside of a river 

meander bend opposite a cutbank (page 36, "Riffle Formation" ). 
* Reach is a segment or section of river of any length chosen by the observer. 

* Sinuosity is a ratio of the length between two distant points in the river following 

the channel, divided by the length between these same distant points along the valley axis. The sinuosity shown in Clark's map on page 13 is 1.1. 

* Slope is the fall of the water divided by the run or distance over which the fall is 

measured. 

* Splay is a deposit of sediment formed during a flood when the river breaks through 

a natural or artificial levee. 

* Stage is the height of the water surface relative to some fixed reference point on 

land. The channel bed is irregular because of sandbars, pools, and point bars, so 

that stage usually does not correspond closely to the local depth. 

* Terrace is a relatively flat surface above the main flood plain of the river that usually represents an older flood plain. 

* Water year ends on September 30, having begun on October 1 of the previous year. 

This year was designated because most of the rivers of the United States reach their 

lowest stages in October. 

* Wavelength is the straight-line distance between two cutbanks or between two 

point bars on a meandering river. 

17 
18 Lewis and Cla rk's Observations and Measurements of Geomorphology and Hydrology, and Changes with Time 

observed a number of places where the river has Changd its Bead at different 

times) ... 11 August 1804 

and Lewis noted in the Missouri River valley about 50 miles above Big Muddy 

Creek in Montana that: 

... river bottom, which is also wider than usual being from 5 to 9 ms. in width; 

traces of the ancient beds of the river are visible in many places through the 

whole extent of this valley .. .3 May 1805 

Frequently they commented on the crookedness (sinuosity) of various tributaries 

near their mouths (the Yellowstone, Musselshell, Smith, and Jefferson Rivers) and 

the crookedness of the Missouri River itself. Above the Great Falls, Lewis mentioned that: · 

... we find it inconvenient to take all the short meanders of the river which has 

now become cooked and much narrower than below, we therefore take it's 

Copy provided by Joslyn Art Museum. Omaha. Nebraska 

Clark's map of the Big Bend of the Missouri 

River was later modified by Prince Maximilian and is sheet I I in the Atlas, volume I, 

Moulton, 1983. 

The view in the photograph of the neck of 

the Big Bend is shown by the blue arrow on 

the map. 

Photo: John Moody 
Geomorphology 

general course and lay down the small bends by the eye on our daily traverse 

or chart .... 15 July 1805 

Above the Platte River of Nebraska, they encountered a couple of unusual single 

bends, and Clark wrote: 

... Burnt Stump on the Bank in the bend to L. S. at which place I was yesterday 

at this place within 3/4 of a mile & round the bends 13 ms ... 10 August 

1804 

... we halted in a bend to the left to take the Meridian altitude, & Dine, 

& Sent one man across where we took Dinner yesterday to Step off the 

Distance across Isthmus, he made it 974 yards, and the bend around is 18314 

miles ... 12 August 1804 

Later, at the Big Bend of the Missouri River (downstream from present sites of 

Pierre, South Dakota, and Big Bend Dam, see Clark's map on page 18), Clark 

listed in his course summary: 

... to a Ceder hill on the L. S in a bend 

opposit the Gorge of this bend where the 

river is only 11/4 mile across & 3 0 Miles 

around ... 20 September 1804 

Measurements of the meanders of the Jefferson River* 

and later adds in the journal that "the bend 

is a Butifull Plain thro which I walked." 

Clark later wrote a detailed account of the 

meandering of the Jefferson River above the 

Big Hole River between Twin Bridges and 

Dillon, Montana. Clark gave the distance 

along the river, the distance along the valley 

axis, and the number of bends (right). From 

these data, the sinuosity of the Jefferson 

River in 1805 ranged from 1.5 to 4.0, and 

the wavelengths of these meanders ranged 

from 0.11 to 0.43 mile. Lewis and Clark 

gave the river width, w, of the Jefferson 

River as 45 yards so that, based on their 

data, the wavelengths, A, of these meanders averaged 9.4 river widths. Much later, 

Leopold and Wolman (1960) developed a 

similar empirical relation, A=10.9wl.Ol, for 

streams worldwide with widths ranging 

from 1 foot to 10,000 feet. 

Date River distance Valley distance Number Wavelength 

1805 (miles) (miles) of bends (miles) 

August 7 7 3 7 0.43 

August 8 5 2 7 0.29 

14 6 35 0.17 

August 9 11 4 16 0.25 

3 1 4 0.25 

August 10 6.5 2 8 0.38 

6.5 2 18 0.11 

August 11 3.0 1 6 0.17 

3.5 1.5 7 0.21 

7.5 2.5 15 0.17 

August 12 5.5 2 9 0.22 

6.5 2 

August 13 4 1 

6 3 

August 14 22 8 

August 15 6 4 

3 1 

August 16 7 3 

4 2 

1.5 1 

August 17 10 4 

*Lewis and Clark called the river the Beaverhead River. It is located approximately 

between the present towns of Twin Bridges and Dillon, Montana. 

Sinuosity 

2.3 

2.5 

2.3 

2.8 

3.0 

3.2 

3.2 

3.0 

2.3 

3.0 

2.8 

3.2 

4.0 

2.0 

2.8 

1.5 

3.0 

2.3 

2.0 

1.5 

2.5 

19 
20 Lewis and Clark's Observations and Measurements of Geomorphology and Hydrology, and Charges with Time 

Landscayes 

Lewis and Clark were keen observers of the landscape with eyes sharpen~d by the 

self-sufficient character of their predominantly agrarian society. They transected 

extensive gradients of physiography and precipitation, unknown to then at first, 

which were imperceptible each day but were later synthesized by Lewis ~'hen they 

finally reached the Rocky Mountains . 

... this convinces 1ne that we have ascended to a great hight since we have 

entered the rocky Mountains~ yet the ascent has been so gradual along the 

vallies that is was scarcely perceptable by land ... 1 0 August 1805 

Their scattered daily vignettes were written while the expedition crossed half a continent but, when collected together, paint a reference picture of the land"capes of 

the Western United States that is 200 years old and helps to determine the changes 

of the landscape with time (page 85, "Geomorphic and Hydrologic Changes in 200 

Years"). The physiographic provinces of these landscapes (opposite) are based on 

surface geomorphic characteristics (Hammond, 1964). Some of these geomorphic 

characteristics were first observed and recorded by Lewis and Clark. In addition 

to the geomorphic characteristics, Lewis and Clark inevitably describec the distributions of the characteristic vegetation of these landscapes. These vegetation 

patterns are indicators of the landscapes, the precipitation regimes, and e~ological 

regions (Bailey, 1995). Many of their observations repeat earlier observafons, and 

so the most descriptive and interesting observations have been selected to illustrate 

their impressions of these provinces. The early observations of landscapes in the 

journals, from about 23 May 1804 to 16 September 1804, are Clark's. J\1o earlier 

entries describing the landscape have been found for Lewis, whose ent-ies start 

about 16 September 1804. He wrote ccA Summary view of the Rivers and Creeks~~ 

during the winter of 1804-05 (p. 336-369, v. 3, Moulton, 1987). They skirted the 

Ozark-Ouachita Highlands coming up the Mississippi River and again going up the 

Missouri River near St. Louis, Missouri. 

OZARK-OUACHITA HIGHLANDS 

.... A ridge of Hills 200 feet high make across the river at this place; and the Gd. 

Tower [Grand Tower] as well as the sugarloaf point~ as also a rock detached 

from both these and likewise the hills~ another side of the bason all appear 

once to have formed a part of the range of hills which cross the Mississippi 

at this place~ and which in the course of time have been broken down by the 

river ... at 314 of a mile above Gabia Creek the high lands juts to the river and 

form a most tremendious Clift of rocks near the Commencement of this Clift 

I saw a Cave ... 26 November 1803 and 4 December 1803 

... the country watered by this river [Gasconade]~ is generally broken~ thickly 

covered with ti1nber and tolerably fertile. the hills which border on the 
Physiographic Provinces 

Lewis and Clark followed a fluvial landscape 

crafted by the Ohio, Mississippi, Missouri, 

Clearwater, Snake, and Columbia Rivers. These 

fluvial landscapes were embedded in larger 

landscapes shaped by glaciers, ancient and 

modern episodes of mountain uplifts, and sediment erosion and deposition. The North-Central 

Lake-Swamp-Moraine Plains and Dakota-Minnesota Drift and Lake-bed Flats were shaped by a 

continental glacier during the last 1 million 

years. The glacier ploughed across the landscape gouging out lakes, pushed the Missouri 

and Ohio Rivers to much of their present positions, and ground the soils into fine silt and 

clay particles. During warm spells at the end of 

the glacial period about 18,000 years ago, this 

fine sediment was transported by wind near 

the edge of the glacier and deposited as thick 

layers of loess (Ruhe, 1969) commonly found 

capping the hills and bluffs of the Middle Western Upland Plain and the West-Central Rolling 

Hills in parts of Missouri, Iowa, and Nebraska. 

The Appalachian Mountains were uplifted about 

270 million years ago to form the core of the 

Appalachian Highlands Province. The Northern 

Rocky Mountains were uplifted about 70 million 

years ago. Erosion of the Rocky Mountains and 

deposition of thick layers of sediment east of the 

mountains helped shape the Mid-continent Plains 

and Escarpments province, which included parts 

of the Great Plains (Trimble, 1980). Regions of 

sedimentary rock deposited and formed in ancient 

oceans were uplifted also to form relatively flat 

areas called plateaus. The Ozark-Ouachita Highlands consist of uplifted rocks older than about 

250 million years, and the dissected Upper Missouri Basin Broken Lands are younger rocks 

uplifted about 5 million years ago (Trimble, 

1980). Modern-day volcanism associated with 

tectonic activity has shaped the Columbia Basin, 

the Cascade-Klamath Ranges, and the PugetWillamette Lowland provinces. 

Columbia Basin ----, Northern Rocky Mountains 

Cascade·Kiamath Ranges Upper Missouri Basin Broken Lands 

Dakota-Minnesota Drift and Lake-bed Flats 

Puget-Willamette Lowland 

Mid-continent Plains and Escarpments 

O zark-Ouachita Highlands 

Adapted from USGS Na~onal Atlas. 1970 

21 
22 Lewis and Clark's Observations and Measurements of Geomorphology and Hydrology, and Changes with Time 

Missouri near the moth of this river are about 300 feet high ... Fort Mandan 

Miscellany, Moulton, 1987, v. 3, p. 338. 

The observation "tolerably fertile" is questionable because little fertile soil is now 

found in the Ozarks (Dale Blevins, written communication, 2002). This suggests 

some degree of caution in evaluating some of Lewis and Clark's observations. They 

did not actually see the Gasconade Basin, and probably this and other information 

came from interviews with travelers or natives of regions they did not specifically 

traverse. Thus, this type of "observation" may be inaccurate. The following observations are reported to be accurate (Dale Blevins, written communication, 2002) . 

... The country watered by this river [Osage River], is generally level & fertile, 

tho' it is more broken on the lower portion of the river; the bottom lands are 

wide, well timbered, and but partially liable to inundation; the soil consists of 

a black rich loam many feet in debth. the uplands also consist of a dark loam 

overlaying a yellow or red clay; a majority of the country consist of plains 

intersperced with groves of timber. the timber still diminishes in quantity as 

you proceed Westwardly with the river ... Fort Mandan Miscellany, Moulton, 

1987, v. 3, p. 339 . 

... [Lamine River] takes it's rise in an open hilly country with Bluewater river 

and some of the Northern branches of the Osage river ... The country through 

which it passes is generally fertile, and consists of open plains and praries 

intersperced with groves of timber ... Fort Mandan Miscellany, Moulton, 

1987, v. 3, p. 342. 

Copy provided by Joslyn Art Museum, Omaha, Nebraska: gift of Enron Art Foundation. 

Karl Bodmer's watercolor of the "Confluence of the Missouri and Gasconade" in the 

Ozark-Ouachita Highlands (April I 3, 1833). 

The Gasconade River is a tributary that 

drains the Ozark-Ouachita Highlands and 

joins the Missouri about midway between St. 

Louis and Jefferson City, Missouri. 
Geomorphology 

MIDDLE WESTERN UPLAND PLAIN 

... On the East Side of the Mississippi a leave! rich bottont extends back about 

3 miles, and rises by Several elevations to the high Country, which is thinly 

timbered with Oake &. On the lower Side of the Missouri, at about 2 

1niles back the Country rises graduilly, to a high plesent thinly timberd 

Country ... undated, Moulton, 1986, v. 2, p. 218 . 

... the Village of St. Charles, situated on the North bank of the river, in a 

narrow tho' elivated plain, tvhich is bounded in the rear by a range of small 

hills; hence the appellation of Petit cote ... Fort Mandan Miscellany, Moulton, 

1987, v. 3, p. 337. 

MIDCONTINENT PLAINS AND ESCARPMENTS 

... Passed some Channing land, I have not Seen any high hils above Charliton 

and the hils below for Several days Cannot to turmed hills but high Land, 

not exceeding 100 abov the high water mark ... 13 June 1804 

... The country through which it [Grand River] passes is similar to that 

discribed on the large Shariton river. about the entrance of this river the 

lands are extreenzly fertile; consisting of a happy nzixture of praries and 

groves, exhibiting one of the 1nost beatifull and picteresk seens that I ever 

beheld .... Fort Mandan Miscellany, Moulton, 1987, v. 3, p. 343 . 

.. . The Countrey about this place is butifull on the river rich & well 

ti1nbered on the S. S. about two miles back a Prarie cams. which is rich 

and interspursud with groves of ti1nber, the County rises at 7 or 8 miles Still 

further back and is roleing- on the L. S. the high lands & Prarie Conzs. in 

the bank of the river and Continus back, well watered ... 17 June 1804 

... This Prarie is butifull a high bottom for 1112 a nzile back and risees to the 

Common leave[ of the Countrey about 70 or 80 feet and extends back out 

of view ... 22 June 1804 

... [Big Blue River] passes through a roling country. the lands are tolerably 

good ... Fort Mandan Miscellany, Moulton, 1987, v. 3, p. 343 . 

... This river [Kansas] takes ifs rise not very distant fro1n the principal branch of 

the Arkanas in a high broken sandy country ... fro1n hence it takes it's course 

nearly East about 300 leagus through fertile and leave!, plains & praries, 

intersperced with groves of tinzbered land; it then enters a country equally 

fertile and well ti1nbered, through which it 1neanders about 20 leagues 

further and discharges itself into the Missouri ... Fort Mandan Miscellany, 

Moulton, 1987, v. 3, p. 343 . 

... about 3/4 of a mile fro1n the entrance ol this river [Kansas] on it's North side 

there is a handsonze bluff about 100 feet high, which furnishes an excellent 

23 
24 Lewis and Clark's Observations and Measurements of Geomorphology and Hydrology, and Changes with Time 

situation for a fortication ... Fort Mandan Miscellany, Moulton, 1987, v. 3, 

p. 344 . 

.. . A high Clift:~ on the upper Side of the Kansis 112 a mile up below the 

Kanses the hills is about 1112 miles from the point on the North Side of the 

Missouries the Hill or high lands is Several miles back:~ ... 2 7 June 18C4 

WEST-CENTRAL ROLLING HILLS 

... and throught i(s [Big Nemaha River] whole course:~ passes through rich:~ and 

level plains:~ and praries. there is some timber on i(s borders ... Fort Mandan 

Miscellany, Moulton, 1987, v. 3, p. 346 . 

... [Nishnabotna River] passes through a fertile country deversifyed with plains 

meadows and woodlands; considerable bodys of the latter appear in some 

parts of this country .... the country lying between the Missouri and this river 

from the Balld pated prarie nearly to i(s mouth:~ is one of the most beautiful:~ 

level and fertile praries that I ever beheld; it is from one to three miles in 

width. there is considerable quantity of timber on the banks of the Missouri:~ 

and but little on the Nishnabatona ... Fort Mandan Miscellany, Mo•1lton, 

1987, v. 3, p. 346-347 . 

.. . This Prarie I call Ball [possibly Bald] pated Prarie:~ from a range of Ball Hills 

parrelel to the river & at from 3 to 6 miles distant from it:~ and extends as 

far up & Down as I can See ... 16 July 1804 

... [Weeping Water Creek] heads in high broken plains near Salt rive:·~ and 

passes through a roling country:~ mostly uncovered with timber and not 

very fertile there is a scant proportion of timber on it banks and some 

clumps of trees are scattered over the face of the country ... Fort Mandan 

Miscellany,Moulton, 1987, v. 3, p. 34 7 . 

... [Mosquito Creek] heads with the Nishnahbatona river in an open co14ntry. 

the Missouri bottom through which it passes is about 6 miles wide:~ level:~ 

extreemly fertile and about one half well covered with timber. .. Fort Mandan 

Miscellany, Moulton, 1987, v. 3, p. 353. 

Lewis and Clark described the interior of the Platte River Basin. It is not clear 

how they obtained the information, but it probably was from discussions with 

the native people. Because the Elkhorn and Loup Rivers are northern tributaries 

to the Platte River, these descriptions reflect the region of north-central ~ 1ebraska 

consisting of West-Central Rolling Hills and the Nebraska Sand Hills. 

[Platte River] passing the heads of the Arkansas at no great distance from 

Santa Fee:~ continues i(s rout to the Missouri:~ through immence level and 
Geomorphology 

fertile plains and meadows, in which, no timber is to be seen except on it's 

own borders and those of it's tributary streams ... Fort Mandan Miscellany, 

Moulton, 1987, v. 3, p. 349. 

[Elkhorn River] it takes it's rise in some sandy plains between the Wolf River 

[Loup] and the Quecurre [Niobrara River]; ... passes through a fertile level 

country, parallel with the Missouri to the River Platte ... Fort Mandan 

Miscellany, Moulton, 1987, v. 3, p. 350. 

[Loup River] This stream takes it's rise in a remarkable large fountain situated 

in a level plain, equadistant between the rivers Quicurre and Plat, at some 

little distance below the Cote nair or Black Hills; from whence it passes 

through level and fertile plains and meadows in which there is scarcely a tree 

to be seen except on it's own borders, ... Fort Mandan Miscellany, Moulton, 

1987, v. 3, p. 350. 

[Bazile Creek] takes it's rise in a broken Hilly and open country between the 

Quicurre and Hart's horn [Elkhorn] rivers. passes through a broken country 

with some handsome plains an praries, ... Fort Mandan Miscellany, Moulton, 

1987, v. 3, p. 357. 

MIDDLE WESTERN UPLAND PLAIN/DAKOTA-MINNESOTA DRIFT 

AND LAKE-BED FLATS 

... The [Big Sioux] disembogues on the N. side above a bluff; ... it takes it's rise 

with the St. Peter's and Vulter rivers, in a high broken and woody country 

called the Hills of the prarie. it waters a deversifyed country, generally 

level fertile and uncovered with timber; in some parts particularly near the 

falls [Sioux Falls], it is broken & stoney, and in others, intersected by a 

great number of small lakes which possess some timber generally on their 

borders ... Fort Mandan Miscellany, Moulton, 1987, v. 3, p. 355. 

Karl Bodmer's watercolor of the 

"Missouri in the Morning below 

Council Bluffs" painted on May 4, 1833, 

in the west-central rolling hills. View 

is looking east and located about I to 

2 miles north of the present city of 

Council Bluffs, Iowa. 

Copy provided by Jos~ Art Museum, Omaha Nebraska; gift of Enron Art Foundation. 

25 
26 Lewis and Clark's Observations and Measurements of Geomorphology and Hydrology, and Changes with Time 

UPPER MISSOURI BASIN BROKEN LANDS 

... this river [Niobrara] takes it's rise in the Black hills, about one hundred 

leagues West of it's mouth, and passes through a variagated country. at it's 

source and for seventy five leagues below the country is mountanous rockey 

and thickly covered with timber, principally pine; ... the country on it's lower 

portion for 25 leagues consists of open plains and meadows, with but a very 

small proportion of timber; ... Fort Mandan Miscellany, Moulton, 1987, v. 3, 

p. 357-358 . 

... mountanious Countrey without water & riseing to 5 or 600 hundred 

feet ... on the S. S. much higher hills than usia! appear to the North distant 

8 miles recently burnt .... The Countrey on the S S. is pore & broken ... Some 

broken Country which Continus about 3 miles back & then is leave! & rich 

all Plains ... 8-11 September 1804 

... found the country in every direction for about three miles intersected with 

deep revenes and steep irregular hills of 100 to 200 feet high; at the tops of 

these hills the country breakes of[fj as usual into a fine leave! plain extending 

as far as the eye can reach. from this plane I had an extensive view of the 

river below, and the irregular hills which border the opposite sides of the 

river and creek. the surrounding country had been 

birnt about a month before and young grass had 

now sprung up to hight of 4 Inches presenting the 

live green of the spring. to the West a high range 

of hills, strech across the country from N. to S and 

appeared distant about 20 miles; they are not very 

extensive as I could plainly observe their rise and 

termination no rock appeared on them and the 

sides were covered with virdue similar to that of 

the plains ... 17 September 1804 

They crossed the 100th meridian on about September 

24, 1804. This is an important climatic line. Annual 

rainfall east of the line is more than 20 inches, and 

Karl Bodmer's watercolor of"Rock 

Formations on the Upper Missouri" 

painted on August 2, 1833. 
Geomorphology 

unaided agriculture is possible; annual rainfall west of the line, with some exceptions, is less than 20 inches and agriculture is exceedingly difficult without some 

form of irrigation. Wallace Stegner (1954), in his book "Beyond the Hundredth 

Meridian," stated the importance of this line succinctly: "That one simple fact was 

to be, and is still to be, more fecund of social and economic and institutional change 

in the West than all the acts of all the Presidents and Congresses from the Louisiana 

Purchase to the present." 

NORTH-CENTRAL LAKE-SWAMP-MORAINE PLAINS 

... [Spring Creek] heads in a small lake a few leagues distant and passes through 

a rich level plain; the land is fertile but without timber. .. Fort Mandan 

Miscellany, Moulton, 1987, v. 3, p. 361. 

Beaver Creek ... heads in some small lakes a few miles from the river, and 

passes through a level fertile and open country ... Fort Mandan Miscellany, 

Moulton, 1987, v. 3, p. 361. 

[Badger Creek] takes it's rise in small lakes, in the open plains, and passes 

through handsome plains and meadows ... Fort Mandan Miscellany, 

Moulton, 1987, v. 3, p. 361-362. 

UPPER MISSOURI BASIN BROKEN LANDS 

... The Northern branch of this river [Cheyenne River] penetrates the Black 

hills, and passes through a high broken well timbered country to it's source, 

the Southern fork takes it's rise in the Black hills, on their E side, and passes 

through a broken country covered with ti1nber, to it's junction with the N 

fork; fro1n whence united, they take their course through a woody and 

broken country fror some few leagus, then entering an open fertile and level 

country it continues ifs rout to the Missouri ... Fort Mandan Miscellany, 

Moulton, 1987, v. 3, p. 359 . 

... The Countrey in this quarter is Generally leave[ & fine Some high Short 

hills, and some ragid ranges of Hills at a Distans ... 18 October 1804 

... the Cannon Ball river ... passes through a variety of country, sonze broken 

& partially timbered, near it's source; other parts broken, hilly and bare of 

timber, and in others beautifull and extensive plains and meadows, with but 

little tinzber, all sufficiently fertile, and some extreemly so ... Fort Mandan 

Miscellany, Moulton, 1987, v. 3, p. 361. 

... The Countrey is fine, the high hills at a Distanc with gradual assents ... 20 

October 1804 

... a butifull Countrey on both Sides of the river ... 24 October 1804 

27 
28 Lewis and Clark's Observations and Measurements of Geomorphology and Hydrology, and Changes with Time 

The last two entries reflect the slight changes in the character of the Upper I 1issouri 

Basin Broken Lands drained by the Heart and Knife Rivers near Bismarck, North 

Dakota. Lewis mentions in his summary that these rivers pass throu.~h open 

plains and meadows, generally fertile, and always untimbered reflecting the westward decrease of timber. Their observations of the landforms broke off during the 

winter at Fort Mandan and began again in the spring of 1805: 

... fro1n it's source it [Yellowstone River] takes it's course for nzany rniles 

through broken ranges of the Rocky mountains, principally broken, and 

stoney, and thickly timbered. the vallies said to be wide in many places 

and the lands fertile. after leaving the Rocky nzountains it descends into 

a country ntore level, tho' still broken, fertile and well ti1nbered. this 

discription of country continues as far down as the Oke-tar-pas-ah-ha, 

where the river enters an open level and fertile country through tuhich it 

continues it's rout to the Missouri; even in this open country it possesses 

considerable bodies of well timbered land ... Fort Mandan Miscellany, 

Moulton, 1987, v. 3, p. 363-364 . 

... it [Big Muddy Creek] meanders through a butifull & extencive vallie as 

far as can be Seen about N 3 oa W. I saw only a Single tree in this fertile 

vallie ... 29 April1805 

... the country appears 1nuch nzore pleasant and fertile than that we have 

passed for several days; the hills are lower, the botto1ns wider, and better 

stocked with tintber, ... 1 May 1805 

... the courant reather stronger than usual and the tuater continues to 

beconte reather clearer, from both which I anticipate a change of Country 

shortly ... 13 May 1805 

... the great number of large beds of stremns perfectly dry which we daily pass 

indicate a country but badly watered ... 17 May 1805 

... The high Country in which tue are at present and have been passing for 

S01ne days I take to be a continuation of what the Indians as well as 

the French Engages call the Black hills. This tract of Country So Called 

Consists of a Collection of high broken and irregular hills and Short Chains 

of Mountains, sometinzes 1 00 miles in width and again beco1ning r·tuch 

narrower, but always nzuch higher than the Country on either Side ... 26 

May 1805 

The dry climate west of the 1 OOth meridian suggested an experiment to Lewis: 

... the air of the open country is asstonishingly dry as well as pure. I found 

by several experiments that a table spoon full of water exposed to the air 

in a saucer would avaporate in 3 6 hours when the murcury did not stand 
Geomorphology 

higher than the temperate point at the greatest heat of the day; my inkstand 

so frequently becoming dry put me on this experiment .. .30 May 1805 

The Rocky Mountains were within view in the clean dry air, perhaps never again 

to be equaled in clarity . 

... I [Clark] took one man and walked out this morning, and ascended the high 

countrey to view the mountains ... ! crossed a Deep holler and assended a 

part of the plain elevated much higher than where I first viewed the above 

mountains; from this point I beheld the Rocky Mountains for the first time 

with Certainty, I could only discover a fiew of the most elivated points above 

the horizon. the most remarkable of which by my pocket Compas I found 

boreS. 60 W. .. 26 May 1805 

... In the after part of the day I [Lewis] also walked out and ascended the river 

hills which I found sufficiently fortiegueing. on arriving to the summit one 

of the highest points in the neighbourhood I thought myself well repaid for 

any labour .... these points of the Rocky Mountains were covered with snow 

and the sun shone on it in such manner as to give me the most plain and 

satisfactory view. while I viewed these mountains I felt a secret pleasure 

in finding myself so near the head of the heretofore conceived boundless 

Missouri; but when I reflected on the difficulties which this snowey barrier 

would most probably throw in my way to the Pacific, and the sufferings and 

hardships of myself and party in them, it in some measure counterballanced 

the joy I had felt in the first moments in which I gazed on them; but as I 

have always held it [little Short of Criminality in Clark's version} a crime 

to anticipate evils I will believe it a good comfortable road until! I am 

compelled to beleive differently ... 26 May 1805 

... I now boar out from the river [Lewis is going by land and Clark is going 

by boat] in order to avoid the steep ravines of the river which usually make 

out in the plain to the distance of one or two miles; ... for the plain through 

which we had been passing possesses no water and is so level that we cannot 

approach the buffaloe within shot before they discover us and take to 

flight ... we passed a ridge of land considerably higher than the adjacent plain 

on either side, from this hight we had a most beatifull and picturesk view of 

the Rocky mountains which wer perfectly covered with Snow and reaching 

from S. E. to the N. of N. W.- they appear to be formed of several ranges 

each succeeding range rising higher than the preceding one until! the most 

distant appear to loose their snowey tops in the clouds; this was an august 

spectacle and still rendered more formidable by the recollection that we had 

them to pass ... 12 June 1805 

29 
30 Lewis and Clark's Observations and Measurements of Geomorphology and Hydrology, and Changes with Time 

While the expedition was above the Great Falls and could see the mountains, the 

expedition was not yet in the mountains . 

. . . The country in most parts very level and in others swelling with gentle rises 

and decents, or in other wirds what I have heretofore designated a wavy 

country destitute of timber except along the water-courses ... 14 July 1805 

NORTHERN ROCKY MOUNTAINS 

... whever we get a view of the lofty summits of the mountains the snow 

presents itself, altho' we are almost suffocated in this confined vally with 

heat .... this evening we entered much the most remarkable clifts that we have 

yet seen. these clifts rise from the waters edge on either side perpendicularly 

to the hight of 1200 feet. every object here wears a dark and gloomy aspect. 

the towing and projecting rocks in many places seem ready to tumble on us. 

the river appears to have forced it's way through this immence body of solid 

rock for the distance of 5 314 miles ... the river appears to have woarn a passage 

just the width of it's channel or 150 yds ... from the singular appearance of 

this place I called it the gates of the rocky mountains ... 19 July 1805 

... the country was rough mountainous & much as that of yesterday until! 

towards evening when the river entered a beautiful! and extensive plain 

country of about 1 0 or 12 miles wide which extended upwards further that 

the eye could reach this valley is bounded by two nearly parallel ranges 

of high mountains which have their summits partially covered with snow 

[probably now the site of the Canyon Ferry Reservoir] ... 21 July 1805 

... and that the river was confined between inacessable mountains, was very 

rapid and rocky insomuch that it was impossible for us to pass either by land 

or water down this river [Salmon River] to the great lake where the white 

men lived ... 13 August 1805 

The Gates of the Rockies are large limestone cliffs bordering the Missouri about 

45 miles upstream from Great Falls, 

Montana. 

Photo: USGS 
Geomorphology 

... we made a number of inquires of those people about the Columbia River 

the Countrey game &c. The account they gave us was verry unfavourable, 

that the River abounded in emence falls, one perticularly much higher than 

the falls of the Missouri & at the place the mountains Closed So Close that 

it was impracticable to pass, & that the ridge Continued on each Side of 

perpendicular Clifts inpenetratable, ... 17 August 1805 

PUGET-WILLAMETTE LOWLAND 

... we were now convinced that there must be some other considerable river 

[Willamette River] which flowed into the columbia on it's south side below 

us which we have not yet seen, as the extensive valley on that side of the 

river lying between the mountainous country of the Coast and the Western 

mountains must be watered by some stream which we had heretofore 

supposed was the quicksand river. but if it be a fact that the quicksand 

river heads in Mount Hood it must leave the valley within a few miles of 

it's entrance and runs nearly parallel with the Columbia river upwards. 

we indeavoured to ascertain by what stream the southern portion of the 

Columbian valley was watered but could obtain no satisfactory information 

of the natives on this head ... 1 April1806 

:f{ood P{ains and 'Terraces 

Lewis and Clark observed within these regional-scale landscapes many specific 

fluvial, valley-scale geomorphic features. One feature was the character of the 

flood plains. Early in the expedition Lewis describes the terraces that compose the 

present and ancient flood plains (page 33, "River Terraces"). While descending the 

Ohio he described the meander features mentioned above and went on to describe 

the flood plains and terraces, which he called bottoms: 

... on each side of the river there are three banks, or suddon rises from the 

summets of which the land generally brake off for a certain distance pretty 

level untill arrives at the high hills before mentioned which appear to give 

a direction to the river- the fist bank or that which the river washes is 

generally from twenty to twentyfive feet, and the bottom lying on a level 

with this is only overflown in remarkable high floods, the consequence is 

that there is no drowneded or marsh lands on this river; this bottom which 

is certainly the richest land from it's being liable some times to be overflowed 

is not esteemed so valuable as the second bottom- The second bottum 

usually rises from twentyfive to thirty feet above the first and is allways safe 

or secure from inundation; usually good when wide from the 3d bank and 

contrary when the bottom is narrow or the river brakes against the 2d near 

31 
32 Lewis and Clark's Observations and Measurements of Geomorphology and Hydrology, and Charges with Time 

the 3rd bank which it sometimes dose what is called the third bottom is 

more properly the high benches of the large range of hills before noticed and 

is of a more varied discription as well as it respects the fertility of ifs soil as 

shape and perpendicular hight~ the river sometimes but very seldom brakes 

against this bank- the second and third of these banks allways run parrallel 

with the high hills and that bordering on the river is of course shat'·~d by 

it ... 2 September 1803 

This description indicates that Lewis's insights into geomorphology were similar 

to those published at nearly the same time by Playfair (1802) in England (page 

6, "Science in 1800: Historical Context"). One wonders whether either Jefferson 

or Lewis had a chance to read Playfair's descriptions before the expedition set 

out in 1803. Darwin (1846) would later publish a description of coastal terraces 

in South America and this work would later be extrapolated to rivers (Miller, 

1883). One also wonders what impact Lewis's observations would haYe had in 

molding the yet unnamed field of geomorphology had he published his observations in the early 1800s. Clark added to this description of the flood plains and 

terraces a description of the typical vegetation that occurred downstream from 

the Kansas River: 

... The Countrey and Lands on each Side of the river is various as usia/ and may 

be classed as follows. viz: the low or over flown points or bottom land~ of the 

grath of Cotton & Willow~ the 2nd or high bottom of rich furtile Soils of the 

grath of Cotton~ Walnut~ Sont ash, Hack berry~ Mulberry~ Lynn & Sycamore. 

the third or high Lands risees gradually from the 2nd bottom (cauht whin 

it Coms to the river then from the river) about 80 or 100 foot roleing back 

Supplied with water the Small runs of (which losees themselves in the brJttom 

land) and are covered with a variety of timber Such as Oake of different 

Kinds Blue ash~ walnut &c. &c. as far as the Praries ... 21 June 1804 

Near the Great Falls, the flood plains were not persistent: 

... scarcely any bottoms to the river; the hills high and juting in on both sides~ 

to the river in many places ... 26 May 1805 

... here the hills recede from the river on both sides~ the bottoms extensive 

particularly on the Stard. side ... here also the river spreads to more than 3 

times ifs former width and is filled with a number of small and handsome 

Islands ... 28 May 1805 

And now above the Great Falls: 

... the bottoms are hadsome level and extensive on both side; the bank on this 

side is not more than 2 feet above the level of the water ... 25 June 1805 
River Terraces 

Playfair (1802) maintained the Huttonian or 

uniformitarian theory (page 6, "Science in 1800: 

Historical Context") that rivers, through slow 

and steady action, have formed terraces at "different levels on which the river has run at different periods of time" (Miller, 1883). Some 

river terraces are abandoned flood plains, and 

the change in the levels can be in response to 

changes in climate or changes in base level. 

The change from a wetter to a drier climate 

will cause a decrease in the height of the annual 

floods such that the old flood plain is abandoned, leaving a terrace. For example, the three 

terrace levels along the Ohio River are perhaps 

most comprehensively described by Ray (1974, 

p. 58-65; see especially his Figure 18) who 

clearly correlates the separate levels with climate change associated with different episodes 

of discharges related to the melting of the great 

continental glaciers during and after the Pleistocene tee ages. 

550 Present flood plain 

500 

Elevation, 

in feet 450 

above sea level 

400 

350 

Terrace of Cary age 

600 550 500 450 

Profiles of the two terraces 

of the Wisconsinan glacial 

age and the flood plain of 

the Ohio River (Ray, 1974). 

The river level is shown as 

a series of steps behind the 

navigation dams. 

Distance downstream, in river miles 

Two examples of a change in base level may 

be ( 1) the sudden drop of the mouth of a river 

in response to changes in sea level or tectonic 

activity or (2) the river slowly incising into the 

valley floor such that " ... each meander will 

sweep past a given point at a slightly lower level 

than that of its predecessor; and each time the 

meander belt swings across the valley from one 

side to the other and back again, it will return 

at a distinctly lower level than the level at which 

it left" (Davis, 1902). Thus, old flood plains are 

abandoned and become terraces. Leopold and 

Miller (1954) described three levels of flood 

plain and terraces along the Powder River in 

Wyoming, which they interpreted as having 

formed entirely after the end of the ice ages. 

Profile of three terrace levels 

on Powder River in eastern 

Montana thought to have 

formed after the end of the 

last ice age (Leopold and 

Miller, 1954). 

33 
34 Lewis and Clark's Observations and Measurements of Geomorphology and Hydrology, and Changes with Time 

They frequently commented on whether or not the lowest bottom or flood plain 

has been flooded: 

It's [Musselshell River] banks abbrupt and about 12 feet high yet never appear 

to overflow while the banks of Judith River were low yet appeared seldom 

to overflow. 

Farther upstream, above the Great Falls, they described the Sun River with: 

... banks which were formed principally of darkbrown and blue clay were 

about the hight of those of the Missouri or from 3 to 5 feet; yet they had not 

the appearance of ever being overflown ... 14 June 1805 

While Lewis's party crossed back over the Continental Divide in 1806 to explore 

the Marias River, he encountered a tributary, Badger Creek, to the southern 

branch, Two Medicine River, of the Marias and commented that: 

... another branch of nearly the same dignity formed a junction with it, 

coming from the S. W this last is shallow and rappid; has the appearance of 

overflowing it's banks frequently and discharging vast torrants of water at 

certain seasons of the year ... 26 july 1806 

Cfianne{-Sca(e (jeomoryfiic :features 

Within the larger valley-scale, geomorphic features are smaller features such as 

riffles, rapids, falls, sandbars, point bars, and braided streams. Riffles, rapids, and 

falls were obstacles encountered while going downstream on the Ohio, Snake, and 

Columbia Rivers. Rapids, falls, sandbars, point bars, and braided channels were 

encountered while going upstream on the Missouri River. 

RIFFLES 

Riffles were mentioned early and frequently in the journals while Lewis and 

Clark were descending the Ohio River, which was especially low, even for the late 

summer and fall season: 

... proceeded to a ripple of McKee's rock where we were obleged to get out all 

hands and lift the boat over about thirty yards; the river is extreemly low; 

said to be more so than it has been known for four year .. .30 August 1803 

... we passed the little horsetale ripple or riffle with much deficulty, all hands 

laboured in the water about two hours before we effected a passage; the 

next obstruction we met was the big-horse tale riffle, here we wer obliged to 

unload all our goods and lift the emty Boat over, about 5 OCock we reach 

the riffle called Woollery's trap, here after unloading again and exerting all 
Geomorphology 

our force we found it impracticable to get over, I therefore employed a man 

with a team of oxen ... ten miles this day ... 1 September 1803 

... [s]truck on a riffle which we got over with some difficulty and in the 

distance of two miles and a half passed 4 others three of which we were 

obliged to drag over with horses; the man charged me the exorbitant price 

of two dollars for his trouble ... struck on a riffle about two miles below the 

town hoisted our mainsail to assist in driving us over the riffle the wind 

blew so heard as to break the spreat of it ... the oxen arrived got off with 

difficulty the oxen drew badly however with their assistance we got over two 

other riffles which lyed just below ... ten miles this day .. 6 September 1803 

... passed several bad riffles and one particularly at the lower end of the long 

reach called Willson's riffle here we were obliged to cut a channel through 

the gravel with our spade and canoe paddles and then drag the boat 

through ... 20 miles this day ... 12 September 1803 

These riffles on the Ohio River represent two of the riffle-forming processes (following page, "Riffle Formation"). On the Missouri River, the expedition seemed to 

have first encountered riffles and rapids during the fall of 1804, just before reaching 

the Mandan villages. Some riffles and rapids may have existed on the lower Missouri 

River but probably were covered by deeper water during the summer. As the expedition approached the Mandan villages, riffles may have been exposed at low water . 

... passed a verry bad riffle of rocks in the evining ... 25 October 1804 

The next mention seems to be while the expedition is passing through the Missouri 

River Breaks in Montana below Marias River and illustrates an understanding of 

the third process, debris riffles, responsible for forming riffles in canyon reaches: 

... the courant strong particularly arround the points against which the courant 

happened to set, and at the entrances of the little gullies from the hills, those 

rivulets having brought down considerable quantities of stone and deposited 

it at their entrances forming partial barriers to the water of the river to the 

distance of 40 or 50 feet from the shore, arround these the water run with 

great violence,. .. 25 May 1805 

.. . scarcely any bottoms to the river; the hills high and juting in on both sides, 

to the river in many places ... late this evening we passed a very bad rappid 

which reached quite across the river ... these are the most considerable rappids 

which we have yet seen on the missouri and in short the only place where 

there has appeared to be a suddon decent ... 26 May 1805 

... the river becomes more rappid and is intercepted by shoals and a greater 

number of rocky points at the mouths of the little gulies than we experienced 

yesterday .... great quantities of stone also lye in the river and garnish it's 

35 
36 

Riffle Formation 

Several types of riffles may exist in rivers: 

(1) bedrock riffles, (2) alluvial riffles, and (3) 

debris riffles. 

Bedrock riffles are formed as a river erodes 

down through the layers of sediment in the 

bed of the river and exposes erosion-resistant 

bedrock across the channel. Alluvial riffles 

form in reaches of rivers that are composed of 

erodible materials and thus are free to adjust 

their channel geometry (Matthes, 1941; Leopold and Wolman, 1957; Meade, 1985; Nelson 

and Smith, 1989). 

Alluvial riffles are formed in meandering rivers. 

As the water enters a bend, the flow near the 

surface turns slightly from the downstream 

direction and heads toward the cutbank while 

the flow near the bottom turns slightly in the 

opposite direction (toward the point bar). The 

flow near the bank erodes sediment from the 

cutbank and from the river bottom adjacent 

to the cutbank in the pool (right). The inward 

component of the near-bottom flow moves the 

eroded sediment out of the pool and toward 

the inner bank. As the water leaves the bend, 

the surface and bottom flows slowly turn 

back to the downstream direction. In order to 

generate an equilibrium topography, the sedi ~ 

ment transport must be the same at all cross 

sections. Most of the sediment removed from 

the cutbank is deposited on the next point bar 

downstream, as Lewis and Clark observed. 

But in order to convey the correct volume of 

passing sediment, the crossing must be somewhat shallower than the average depth of 

the channel near the apex of the bend. This 

requires that sediment be added to the riffle, 

that occupies the relatively shallow area where 

the curvature of the bend changes direction. 

The water then exits the next bend and the 

erosion and deposition process is repeated. 

Alluvial Riffles 

This aerial photograph of a meandering river was 

taken after the 1978 flood on the Powder River in 

southeastern Montana. Alluvial riffles are at the crossings between bends. Notice that some sand (white 

areas) was deposited as floodwaters overflowed the 

banks and slowed down while crossing the point bar 

through trees. Older meander scrolls can be seen 

outlined by cottonwood trees. 

Debris riffles are formed by lateral inputs of 

debris into the main channel from hillslopes 

or from tributaries. The resulting debris fan 

partially fills the river and creates a narrower 

and shallower channel (below). These debris 

deposits are reworked by the river leaving the 

coarse sediment in the channel as a riffle and 

forming separation, reattachment, channelmargin deposits (Schmidt and Graf, 1990). 
Geomorphology 

borders~ ... the river is generally about 200 yds. wide~ very rappid and has a 

percept able fall or declination through ifs whole course ... 2 7 May 1805 

... tue e1nployed the chord generally to which we also gave the assistance of 

the pole at the riffles and rocky points; these are as numerous and many of 

thenz nzuch worse than those we passed yesterday; arround those points the 

water drives with great force~ and we are obliged in ntany instaces to steer 

our vessels through the appertures fanned by the points of large sharp rocks 

which reach a few inches above the surface of the water, here sould our 

chord give way the bough is instantly drivin outwards by the stream and the 

uessel thrown with her side on the rocks ... 28 May 1805 

RAPIDS 

Lewis realized that the expedition had ascended to a great hight since we have 

entered the rocky Mountains, and therefore, the rivers in the Columbia River Basin 

would be steeper than the Missouri River: 

... but this I can scarcely hope from a knowledge of its [the Columbia River] 

having in it conzparitively short course to the ocean the same number of feet 

to decend which the Missouri and Mississippi have franz this point to the 

Gulph of Mexico ... 1 0 August 1805 

... The River [Salmon River] franz the place I left nzy party to this Creek is 

almost one continued rapid, five verry Considerable rapids the passage of 

either tuith Canoes is entirely irnpossable~ as the water is Confined betwen 

hugh Rocks & the Current beeting from one against another for Sonze 

distance below &c. &c. at one of those rapids the 1nountains Close So Clost 

as to prevent a possibility of a portage with great labour ... This river is about 

1 00 yards wide and can be forded but in a few places. below my guide and 

1naney other Indians tell n1e that the Mountains Close and is a perpendicular 

Clift on each Side~ and Continues for a great distance and that the water 

runs with great violence from one rock to the other on each Side foaming & 

roreing thro rocks in every direction~ So as to render the passage of any thing 

impossible ... The Torrents of water which come down aftr a rain carries with 

it enzence nu1nbers of those Stone into the river ... 23 August 1805 

Instead of trying to go down the Salmon River, the expedition went by horse overland to the confluence of the Clearwater and North Forth of the Clearwater Rivers 

near what is now Orofino, Idaho. This was a difficult passage through what was 

essentially a rain forest of dark, heavy timber. The expedition had a difficult time 

finding a navigable river. The native peoples name for the Salmon River means 

"River of No Return." The Lochsa River was and is today (ClassV-VI whitewater 

river) a boulder-strewn, steep tributary to the Clearwater River, filled with rapids, 

37 
38 Lewis and Clark's Observations and Measurements of Geomorphology and Hydrology, and Charges with Time 

and whose name means "Rough Water" in Nez Perce (Mike Beckwid', written 

communication, 2002). However, they proceeded on and found the C1 

~arwater 

River, built canoes, and set off down the Clearwater on October 7, 1805: 

... The after part of the day Cloudy proceded on passed 10 rapids which wer 

danjerous the Canoe in which I was Struck a rock and Sprung a leak in the 

3rd rapid ... 7 October 1805 

... A Cloudy morning ... passed 15 rapids four Islands and a Creek on the Stard 

Side at 16 miles just below which one canoe in whick Serjt. Gass was Stearing 

Course and distance on the Clearwater River for October I 0, 1805 

Bearing Distance 

(miles) 

South 

S.20°W 1112 

West 112 

s. 30° w 3 

West 2 

s. 30° w 4 

West 2 

sw 1 

South 1 

S80W 3 

West 

Comments 

mile passed a bad rapid at the head of an Isd. on Ld. Side 

miles to a Ld bend, passed a Isd on Ld. Side rapid at the Head bad. pass<?.d 

Lower pt. of the other at the mouth of a run on Stand. 

to a St. bend passed a Small Isd. Ld side and a rapid 

mile to a Ld. bend passed a Creek Cg on the Ld Side at 112 a mile on which is 

Cotton wood bottoms Inds. Camp below the Creek 

miles to the head of an Isd. at bad rapid on bother Sides Curt [current] on the 

right Side 

mile pd. a rapd at Lower point of Isd & rapid at 1 mile, a rapd at 1112 miles 

rocky bottoms on each Side a rapid at 2112 miles a run & (Inds. Camp) on Stard 

Sd at 3 miles a rapid at 3112 miles to a Lard. bend, low plain 100 ft 

mile to a Stard bend, {passed an Indian bathing in hot bath) rapid an Island on 

the L. S. Shale waters at the head opsd. to which verry bad rapid we Call raged 

rapid one Canoe Struck & lodged Sprung a Leak onload Passed Several Inds 

camps on the Island. Took Meridian altitd. on the Island with Sextent made 

it 74°26' Latd 46° 29' 217110" North 

mile to a bend on the St. Side psd 2 rapid 

mile to the L. bend passed 2 rapid a large bottom on each Side 

miles to the mouth of a Large fork Caled by the Inds. Ki-moo-e-nem 

[Snake River] passed 2 rapids Isd. in mouth 

mile to aLd. bend ps Shore in the mouth. Wind high which obliged us to 

Stop. Kimooenem has two forks on the South Side, & Camps of lnds. all 

the way up 2d fork called Par-nash-te about 50 ms. camped on Std. Side to 

make observt 

Taken from p. 253-254, volume 5, Moulton, 1988. 
Geomorphology 

and was nearle turning over, She Sprung a leak or Split open on one Side and 

Bottom filled with water & Sunk on the rapid ... 8 October 1805 

Clark's course and distances for October 10, 1805, give a good idea of the rapids on 

the Clearwater River to the confluence with the Snake River. Course and distance 

read with a similar detailed accounting of the rapids downstream to the mouth of 

the Snake River (below). 

Rapids also dominated the journal entries while they went down the Snake River: 

... we passed to day [blank] rapids Several of them very bad and came to at the 

head of one (at 30 miles) on the Stard. Side to view it before we attemptd. 

to dsend through it. The Indians had told us was verry bad- we found long 

and dangerous about 2 miles in length, and maney turns necessary to Stear 

Clare of the rocks, which appeared to be in every direction. The Indians went 

through & our Small Canoe followed them, as it was late we deturmined to 

camp above until/ the morning ... 12 October 1805 

... at 12 miles we Came too at the head of a rapid which the Indians told me 

was verry bad, we viewed the rapid found it bad in decending three Stern 

Canoes Stuk fast for Some time on the head of the rapid and one Struk a 

rock in the worst part, fortunately all landed Safe below the rapid which was 

nearly 3 miles in length ... after dinner we Set out and had not proceded on 

two miles before our Stern Canoe in passing thro a Short rapid opposit the 

head of an Island, run on a Smoth rock and turned broad Side, the men got 

out on the [rock] all except one of our Indian Chiefs who Swam on Shore, 

The Canoe filed and Sunk ... 14 October 1805 

... a Suck cession of Sholes, appears to reach from bank to bank for 3 miles which 

was also intersepted with large rocks Sticking up in every direction, and the 

chanel through which we must pass crooked and narrow. we only made 20 

miles today, owing to the detention in passing rapids &c ... 15 October 1805 

FALLS 

The Great Falls of the Missouri River The first major falls that Lewis and Clark 

encountered were the Great Falls of the Missouri River. They spent about a 

month (June 16-July 14, 1805) portaging the Great Falls, and during this time 

Clark measured their profile. He gives the course, horizontal distances in poles 

(see "Conversions" and "Glossary") and vertical distances in feet. The total 

horizontal distance is 14.83 miles with a total drop of 360 feet or an average 

slope of 0.005. Superimposed upon Clark's profile of the Great Falls (next page) 

are the approximate locations of four dams. The largest fall was 93.75 feet high 

according to Clark and is now part of the Ryan Dam. Today, Crooked and 

Rainbow Falls can still be seen and were measured by Clark to be 34 and 47.67 

feet high, respectively. 

39 
40 

A comparison of profiles 

shows a close correlation 

between the one made by 

Lewis and Clark's Observations and Measurements of Geomorphology and Hydrology, and Changes with Time 

Major falls on the Columbia River The final obstacles on the Columbia River 

were three major falls. The Great Falls (later Celilo Falls), the Falls at the Short and 

Long Narrows (later The Dalles), and the Great Rapids (later The Cascades) were 

each mapped by Clark {pages 42, 43, and 44). These maps record the morphology 

in 1805 of the falls which today are all under water impounded in the reservoirs 

behind The Dalles (footnote 11, p. 326, v. 5, Moulton, 1988) and Bonneville 

Dams. At Celilo Falls: 

. . . the waters is divided into Several narrow chanels which pass through a 

hard black rock forming Islands of rocks at this Stage of the water ... 22 

October 1805 

These numerous channels observed and mapped by Clark represent channels carved 

in the Columbia River basalts by flow velocities {up to 40 miles per hour) associated with catastrophic floods that emanated from Lake Missoula, in what is now 

Profiles of the Great Falls of the Missouri 

Lewis and Clark and the 3,400 ---------------------

other by the USGS. 

Land surface 

altitude, 

in feet above 

sea level 

The Black Eagle Dam is 

located just above Rainbow 

and Crooked Falls. 

Photo: USGS 

2,576 2,580 2,584 2,588 

--William Clark's measurements 

- USGS 7.5-minute topographic map 

... noting the particular Cataracts Cascades 

and the hight they fall as Measured, together 

with an estimate of the decline of the water 

in rapids &c. &c. 

June 17 & 18th 1805 William Clark 

2,592 

Distance upstream from the Mississippi River, in miles 
Geomorphology 

0 

This 1888 map from the U.S.Army Corps of Engineers shows the location of 

several of the major rapids and falls along the lower reach of the Columbia 

River. Today this reach is under water impounded by the Dalles Dam. 

T 0 

N 

\ 

0 '{ •.... _ ..... - ·--

t~ --

~.,.= 

J: Washington State University 

Site of t he The Dalles o r Five-Mile Rapids 

Dall es Dam (Long Narrows) 

Ten Mile Rapids 

(Short Narrows) 

Montana. The ice dam across the outlet of the lake broke several times at the end 

of the ice age about 16,000 to 12,000 years ago and released about 400 cubic miles 

of water each time. The water flowed across what is now eastern Washington and 

down the Columbia River (Bretz, 1930; Allen and others, 1986). A short distance 

downstream were the two falls at The Dalles. Dalles means "gutter" in French and 

refers to the numerous slotlike channels in the basalt probably created by the Lake 

Missoula Floods. At the beginning of a narrow reach of the Columbia River: 

... The first pitch of this falls is 20 feet perpendicular, then passing thro'a narrow 

Chane[ for 1 mile to a rapid of about 18 feet fall below which the water has 

no perceptable fall but verry rapid See Sketch No. 1. It may be proper here 

to remark that from Some obstruction below, the cause of which we have 

not yet learned [see next excerpt below], the water in high fluds (which are 

in the Spring) rise <nearly> below these falls nearly to a leave[ with the water 

above the falls; the marks of which can be plainly trac'd around the falls. 

at that Stage of the water the Salmon must pass up which abounds in Such 

great numbers above .. . 24 October 1805 

This observation makes an interesting connection between geomorphology, 

hydrology, and biology. The obstruction is the Long Narrows, which is described in 

the next excerpt and was later known as Five-Mile rapids. The peak runoff on the 

41 

-MAPCOLUM BIA- RIVER 

THE DALLES •• CELILO, Or. 

-1881.-

-. 

R 11,.. 

Celilo Falls 

(The Great Falls) 
42 Lewis and Clark's Observations and Measurements of Geomorphology and Hydrology, and Changes with Time 

Photograph shows the Celilo Falls as viewed from 

downstream and looking upstream before the 

construction ofThe Dalles Dam completed in 1960. 

The view in the photograph is shown by the blue 

arrow on the map. 

Clark's map of the Celilo Falls 

on the Columbia River. 

Map: American Philosophical Society 

Columbia River at The Dalles occurs in summer (page 68, "River Hydrographs"), 

and the salmon runs have probably evolved to peak during the summer. Chinook 

salmon begin arriving in February, but the main population of fish do not arrive 

until May, June, and July and then diminish rapidly after July (Chapman, 1986). 

Thus, the salmon can surmount the falls at the only time of year when it would be 

possible as suggested by Lewis and Clark. In drought years, when the peak flow was 

much less, the flow may not have backed up to a sufficient depth to allow the salmon 

to pass the falls. Just downstream from The Great Falls, the Columbia River went 

through the Short Narrows: 

.... from the top of which I could See the dificuelties we had to pass for Several 

miles below; at this place the water of this great river is compressed into a 

Chane/ between two rocks not exceeding forty five yards wide and continues 

for a 114 of a mile when it again widens to 200 yards and continues this width 

for about 2 miles when it is again intersepted by rocks. This obstruction in 

the river accounts for the water in high floods riseing to Such a hite at the 

last falls. The whole of the Current of this great river must at all Stages pass 

thro' this narrow chanel of 45 yards wide ... 24 October 1805 

and then through the Long Narrows where: 
Geomorphology 

... the Chane! is narrow and compressed for about 2 miles, when it widens 

into a deep bason to the Stard. Side, & again contracts into a narrow chanel 

divided by a rock .... 24 October 1805 

The deep bason may also have been created by the Lake Missoula Floods, which 

could pluck out large areas of bedrock in a somewhat random pattern. Because 

the portage was impractiable with our large Canoes, we Concluded to Make a 

portage of our most valuable articles and run the canoes thro. After passing the 

Long Narrows they 

... proceeded on down the water fine, rocks in every derection for a fiew miles 

when the river widens and becoms a butifull jentle Stream of about half a 

mile wide ... 25 October 1805 

Upstream from the Cascades, Clark made an interesting observation: 

... a remarkable circumstance in this part of the river is, the Stumps of pine 

trees are in maney places are at Some distance in the river, and gives every 

appearance of the rivers being darned up below from Some cause which I am 

not at this time acquainted with, the Current of the river is also verry jentle 

not exceeding 1 112 mile pr. hour and about 3/4 of a mile in width .... here 

Clark's map of The Dalles, or 

'"! Short and Long Narrows, on 

; the Columbia River. Westward "i· 

; flow is from bottom to top. <;' 

University of Washington 

43 

This lithograph looking 

downstream into the Long 

Narrows was made from 

an engraving by J.M. Stanley 

in 1853. 

The view in the engraving 

is shown by the blue arrow 

on the map. 
44 Lewis and Cla rk's Observations and Measurements of Geomorphology and Hydrology, and Changes with Time 

the river widens to about one mile large Sand bar in the middle, a Great 

[rock] both in and out of the water, large <round> Stones, or rocks are also 

permiscuisly Scattered about in the river .. .3 0 October 1805 

Clark observes the remnants of the landslide downstream, a day later on October 

31, 1805 (opposite): 

... This Great Shute or falls is about 112 a mile with the water of this great river 

Compressed within the Space of 150 paces in which there is great numbers 

of both large and Small rocks, water passing with great velocity forming & 

boiling in a most horriable manner, with a fall of about 20 feet, below it 

widens to about 200 paces and current gentle for a Short distance. a Short 

distance above is three Small rockey Islands, and at the head of those falls, 

three Small rockey Islands are Situated Crosswise the river, Several rocks 

above in the river & 4 large rocks in the head of the Shute; those obstructions 

together with the high Stones which are continually brakeing loose from the 

This 1929 photograph is looking 

downstream into Cascade Rapids.The 

Bonneville Dam was constructed at 

the terminus of the rapids. 

Clark's map of the Cascades 

Rapids [Great Shute] ofthe 

Columbia River. 

The view in the photograph 

is shown by the blue arrow 

on the map. 
Geomorphology 

0 

Bonneville Landslide 

2miles 

The stumps of the "submerged forest" have 

puzzled many scientists since Lewis and Clark 

made their observations. Current thinking attributes the stumps to the submergence of a forest 

by water backed up behind the Bonneville landslide on the Columbia River, near the former 

location of Cascade Rapids. The cause of the 

landslide is not clear, but the stumps have been 

dated to provide an estimate of when the landslide occurred. Lawrence and Lawrence (1958) 

estimated the date to be between A.D. 988 and 

1588; Pringle and Schuster (1998) and Schuster and Pringle (2002) estimated ages ranging 

from A.D. 1500 to 1760 on the basis of radiocarbon dating. More recent radiocarbon dates 

(Jim O'Connor, written communication, 2002) 

indicates the blockage of the Columbia River 

was between A.D. 1400 and 1465. 

mountain on the Stard Side and roleing down into the Shute aded to those 

which brake loose from those Islands above and lodge in the Shute, must be 

the Cause of the rivers darning up to Such a distance above, where it Shows 

Such evidant marks of the Common current of the river being much lower 

than at the present day .. .31 October 1805 

SANDBARS 

On the Missouri, sandbars were numerous and the most troublesome feature 

encountered in June of 1804. In what is now Iowa and Missouri, the expedition 

had to labor upriver against the peak runoff (page 68, "River Hydrographs") 

through the sandbars (see the stippled areas on Clark's map on pages 13 and 18) 

and sometimes over them: 

... passd. a bad Sand bar on which we Stuck for a Short time this is Said to be 

the worst part of the river ... 15 June 1804 

and near the White River in South Dakota 

... the Sandbars So noumerous; it is not worth mentioning them ... 9 September 1804 

45 
46 

River Snags 

Snags are tree stumps and parts of trees buried 

in sandbars. Snags continue to trap sediment 

as the river flows among them. If enough snags 

are present in an area, trapped sediment may 

accumulate vertically until the sandbar is high 

enough to become new flood plain and alter 

the course of the river. During later floods, 

the river may cut a channel through the flood 

plain, which was once a sandbar, and expose 

these buried tree parts. In some tributaries to 

the Missouri River, ~hese buried snags have 

ages ranging from 100 to 11,270 years before 

the present (Guyette and Dey, 2001). Karl 

Bodmer's painting in 1833 is probably the best 

visual impression of snags on the Missouri 

River. Mark Twain's paragraph in "Roughing It" (written about his trip up the Missouri 

River by steamboat in 1861) is among the best 

verbal descriptions of snags: 

We were six days going from St. Louis "St. ]oe"-a trip that was so dull, and sleepy, 

and eventless that is has left no more impression on my memory than if its duration 

had been six minutes instead of that many days. No record is left in my mind, now, 

concerning it, but a confused jumble of savage-looking snags, which we deliberately 

walked over with one wheel or the other; and of reefs which we butted and butted, and 

then retired from and climbed over in some softer place; and of sand bars which we 

roosted on occasionally, and rested, and then got out our crutches and sparred over. In 

fact, the boat might almost as well have gone to St. joe by land, for she was walking 

most of the time, anyhow-climbing over reefs and clambering over snags patiently and 

laboriously all day long. The captain sbid she was a "bully " boat, and all she wanted 

was more "shear" and a bigger wheel. I thought she wanted a pair of stilts, but I had 

the deep sagacity not to say so. 
Geomorphology 

... Set out verry early, the river wide & Shallow the bottom narrow, & the river 

Crouded with Sand bars ... 11 September 1804 

... we found great dificuelty in passing between the Sand bars the water Swift 

and Shallow, it took 314 of the day to make one mile ... 12 September 1804 

These sandbars were populated by snags (opposite) . 

.. . a fair morning, the River rise a little we got fast on a Snag Soon after we Set 

out which detained us a Short time ... 9 June 1804 

... we Set out and proceeded on under a gentle breeze from the N. W passed 

Some verry Swift water Crouded with Snags ... 22 June 1804 

... the bank was falling in and lined with Snags as far as we could See down, ... 14 

July 1804 

... a bend to L.S. choked up with Snags ... 8 August 1809 

It was not until May of 1805 downstream from the Musselshell River that the 

number of sandbars seem to decrease: 

... the sandbars, and with them the willow points have almost entirely 

disappeared ... 17 May 1805 

... there are now but few sandbars, the river is narrow and current gentle ... 18 

May 1805 

... fewer sandbars and the courant more gentle and regular ... 22 May 1805 

On the return trip in 1806, they traveled down the Missouri River downstream 

from the Yellowstone River after the summer peak runoff in later summer and fall, 

and Clark observed that: 

... in places where there was Sand bars in the fall 1804 at this time the main 

Current passes, and where the current then passed is now a Sand bar-Sand 

bars which were then naked are now covered with willow Several feet 

high ... 20 August 1806 

Near the Big Sioux River he noted that: 

... the river [Missouri] much crowded with Sand bars, which are very differently 

Situated from what they were when we went up .. .3 September 1806 

and 

... passed the enterance of the great river Platt which is at this time low the water 

nearly clear the Current turbelant as usia/; the Sand bars which Choked up 

the Missouri and Confined the [river?] to a narrow Snagey Chane/ are wastd 

a way and nothing remains but a fiew Small remains of the bear [bar] which 

is covered with drift wood ... 9 September 1806 

47 
48 

This view of the Powder 

River was taken near the 

Wyoming-Montana State 

line. 

Photo: John Moody 

Lewis and Clark 's Observati ons and Measurements of Geomorph ology and Hydrology, and Changes with Time 

Point bars are a special subset of sandbars and were first mentioned as a batteau (a sandy beach on the inside curve of a river, 

footnote 9, p. 299, v. 2, Moulton, 1986). Clark described the 

maintenance of point bars on the Missouri River upstream from 

the Platte River: 

... In every bend the banks are falling in from the Current being 

thrown against those bends by the Sand points which inlarges 

and the Soil I believe from unquestionable appearns. of the 

entire bottom from one hill to the other being the mud or ooze 

of the River at Some former Period mixed with Sand and Clay 

easily melts and Slips into the River, and the mud mixes with the water & the 

Sand is washed down and lodges on the points ... S August 1804 

and later on the Big Horn River: 

... like the Missouri, it washes away its banks on one Side while it forms 

extensive Sand bars on the other side ... 26 July 1806 

BRAIDED REACHES 

No mention was made of the braided character of the Missouri until October 3, 

1804, when there is a brief entry: we attempted several chanels and could not 

find water to assend. Multiple channels, separated by islands and sandbars, are 

shown in Clark's maps. Prior to October 3, 1804, the river stage may have been 

high enough that the expedition's boats could navigate the channels. Lewis and 

Clark frequently would give the measured width of the Missouri or mention 

that it was wide or narrow. However, near the Cheyenne River in South Dakota, 

more observations of the braided character appear in their journals, perhaps 

because the river stage had fallen. If they had traversed the lower Missouri River 

in September-October rather than in May-June, they may have had more comments about the braided character of the river . 

... we were obliged to Drop down 3 miles to get the Chane[ Suft. deep to pass 

up .. .4 October 1804 

... we proceeded on found the river Shale we made Sever!. attempts to find 

the main Channel between the Sand bars, and was obliged at length to Drag 

the boat over to Save a league which we must return to get into the deepest 

Channel, we have been obgd to hunt a Chan!. for Some time past the river 

being devided in many places in a great number of Chanels ... 6 October 1804 

... many Sand bars and bad places, water much devided between them ... 26 

October 1804 

... the river for several days has been as wide as it is generally near it's mouth, 

tho' it is much shallower or I should begin to dispair of ever reaching it's 
Channel Patterns 

Why a river is straight, meandering, or braided 

has been studied by many scientists since 

Lewis and Clark made their observations. 

These channel patterns represent a continuum, 

and all three types may be found in the same 

river. For example, Russell (1954) mentions 

that the Meander River in Turkey, from which 

the term is derived, has both meandering and 

braided reaches. With some exceptions, the 

Missouri River was generally a braided river 

downstream from the Great Falls and a meandering river in unconfined reaches upstream 

from the falls. Channels with sinuosity {pages 

16 and 17, "River Terms') greater than 1.5 

was a definition used by Leopold and Wolman 

(1957) to separate straight reaches from meandering reaches within the continuum of channel patterns. Scientists have found that the 

type of channel pattern also depended upon 

the channel width, the discharge, the channel 

slope, the grain size of the sediment on the riverbed, and the amount and frictional resistance 

of the sediment in the channel (Matthes, 1941; 

Leopold and Wolman, 1957; Langbein and 

Leopold, 1966; Schumm, 1977; van den Berg, 

1995). In general, for a fixed discharge and 

median diameter, meandering reaches will have 

slopes less than the slopes of braided reaches 

(below). Similarly, for a fixed slope and grain 

size, braided reaches will have a greater discharge than meandering reaches. The channel 

pattern can also be changed by adding more 

sediment to the channel through such processes 

as landslides (Lisle and others, 1983), dumping 

mine tailings into a river (Gilbert, 1917), and 

erosion from watersheds burned by wildfire 

(Moody, 2001). 

1000 --- --- --- --- -----

Stream power, 

pgSQ/W, watts per 

square meter 

Braided channels / 

100

~ Meandering channels 

10 ---------- --- --- -

0.1 10 100 1000 

Median grain size, in millimeters 

The variable on the vertical axis is called the unit stream power or 

stream power per unit width, where p is the density of water and g 

is the acceleration of gravity, and each are constants. S is the channel 

slope, Q is the discharge at bankfull, and W is the channel width. 

Adapted from van den Berg (1995). 

49 
50 

Braided reach of the 

Platte River, Nebraska. 

Photo: University of Nebraska 

Lewis and Clark's Observations and Measurements of Geomorphology and Hydrology, and Changes with Time 

source; it has been crouded today with many sandbars; the water also 

appears to become clearer, it has changed it's complexin very considerably ... 9 

May 1805 

and above the Gates of the Rocky Mountains: 

... the river immediately on entering this valley assumes a different aspect and 

character, it spreads to a mile and upwards in width crouded with Islands, 

some of them large, is shallow enough for the use of the seting pole in almost 

every part and still more rappid than before; it's bottom is smooth stones 

and some large rocks as it has been since we have entered the mountains ... 21 

July 1805 

... the river is still divided by a great number of islands, it channels sometimes 

seperating to the distance of 3 miles; the current very rapid with a number 

of riffles; the bed gravel and smooth stones ... 23 July 1805 

They mentioned the activities of the beaver along this braided reach within the 

mountains: 

... we saw many beaver and some otter today; the former dam up the small 

channels of the river between the islands and compel! the river in these parts 

to make other channels; which as soon as it has effected that which was 

stoped by the beaver becomes dry and is filled up with mud sand gravel 

and drift wood. the beaver is then compelled to seek another spot for his 

habitation wher he again erects his dam. thus the river in many places among 

the clusters of islands is constantly changing the direction of such sluices as 

the beaver are capable of stoping or of 20 yds. in width. this anamal in that 

way I beleive to be very instrumental in adding to the number of islands with 

which we find the river crouded ... 24 July 1805 

'Erosion, Sediment Transyort, ana 1Jeyosition 

Lewis and Clark also made observations of processes that change the geomorphic 

features. They made a few observations of hillslope erosion, but the majority of the 

entries in their journals dealt with bank erosion along the Missouri River. 

EROSION 

Clark described the erosion process near the White River in South Dakota: 

... The rain Continued the Greater part of the day in My ramble I observed, 

that all those parts of the hills which was Clear of Grass easily disolved and 

washed into the river and bottoms, and those hils under which the river run, 

Sliped into it and disolves and mixes with the water of the river, the bottoms 
Geomorphology 

of the river was covered with the water and mud frame the hills about three 

Inches deep- those bottoms under the hils which is Covered with Grass, 

also receves a great quantity of mud ... 14 September 1804 

Clark observed mass wasting near the Bald Pate Prairie in the vicinity of the 

Nishnabotna River: 

... this Hill has Sliped from the top which forms a Bluff above & 200 foot 

above the water, about 314 of a mile in length & about 200 feet in Depth has 

Sliped into the river ... 18 July 1804 

and later Lewis noted some mass wasting near the mouth of the Little Missouri: 

... the lard. shore on which I walked was very broken, and the hills in many 

places had the appearance of having sliped down in masses of several acres 

of land in surface ... 14 April1805 

Bank erosion was noted more frequently in the journals than hillslope erosion but 

was limited to the period from May 15, 1804 (when they started up the Missouri 

River) to about June 28. This was a rainy period according to the journals. Clark 

noted that the river begin to rise on May 28, then rises fast, (May 30), rose last 

night a foot (June 6), rise a little (June ), riseing fast, (June 15), raised 3 Inches last 

night (June 21), ros.e 4 Inchs last night (June 22), the river rose a little last night 

(June 27), and the river Missourie has raised yesterday last night & today about 2 

Foot this evening it is on a Stand (June 28). The river apparently crested on June 

28, 1804. This rise of the river was after the spring rise associated with snowmelt 

at lower elevations (page 68, "River Hydrographs"). The larger river rise is the 

annual inundation of the river, which usually happen in the month of June near the 

mouth. Smaller rises are the consequence of local storms. Most of the bank erosion 

was observed during periods when the river was rising . 

... we attempted to pass up under the Lbd. Bank which was falling in So fast 

that the evident danger obliged us to Cross between the Starbd. Side and a 

A bank failure of a type that might have been 

seen by Lewis and Clark. This example was 

photographed on the Ob River in Siberia near 

Khanty-Mansiysk and has birch and conifer trees 

on the bank rather than the cottonwood and 

willow trees Lewis and Clark would have seen. 

51 
52 

Sediment-laden (muddy) 

water from the Knife River 

flowing into the Missouri 

River Oune 200 I). The 

crumbling bank is a source 

of the sediment. 

Lewis and Clark's Observa tions and Measurements of Geomorphology and Hydrology, and Changes with Time 

Sand bar in the middle of the river ... 24 May 1804 

... The banks are falling in Verry much to day ... 6 June 1804 

... immense Current & falling banks on the S.S ... 14 June 1804 

... all at once the river became Crowded with drift that it was dangerous to 

cross this I Suppose was from the caveing in of the banks at [t]he head of 

Some Island above ... 2 July 1804 

... the Banks washing away & trees falling in constantly for 1 mile .. .4 August 

1804 

Some bank erosion was noted after a local storm: 

... My notes of the 13th of July by a Most unfortunate accident blew over 

Board in a Storm in the morning of the 14th .. last night at about 10 oClock a 

violent Storm of wind from the N.N.E. which lasted with Great violence for 

about one hour, at which time a Shower of rain Succeeded ... 13 July 1804 

... Some hard Showers of rain this morning [14th] prevented our Setting out 

until! 7 oClock ... and the opposit Shore, the bank was falling in and lined 

with Snags as far as we could See down ... 14 July 1804 

and some bank erosion involved large areas: 

...... passed a place above the Island L.S. where about 20 acres of the hill 

has latterly Sliped into the river above a clift of Sand Stone for about two 

miles ... 16 July 1804 

The banks eroded and so did sandbars; the Missouri River was a dynamic 

system-always changing: 

... last night or reather this morng at a half past one oClock the Sand bar on 

which we Camped began to give way, which allarmed the Serjt on guard & 
Geomorphology 

the noise waked me, I got up and by the light of the moon observed that 

the Sand was giving away both above & belay and would Swallow our 

Perogues in a few minits, ordered all hands on board and pushed off we 

had not got to the opposit Shore before pt. of our Camp fel into the river ... 21 

September 1804 

No entries of bank erosion are found after the end of July and through the 

remainder of the summer into the fall. A few entries appear in April 1805 as 

the expedition started up the Missouri River from their winter quarters at Fort 

Mandan. Once again bank erosion seems to be associated with the rising river. 

However, the expedition probably did not encounter the annual rise in 1805, 

which probably peaked after April. 

SEDIMENT TRANSPORT 

Lewis and Clark made observations of eolian transport, suspended-sediment 

transport, and bedload transport. Eolian transport was first mentioned in August 

1804 near the Big Sioux River and indicated transport to the east: 

... The Wind blew hard <West> {another editor probably meant West wind, 

based on the prevailing winds in Montana and North Dakota] and raised 

the Sands off the bar in Such Clouds that we Could Scercely <See> this Sand 

being fine and verry light Stuck to every thing it touched, and in the Plain for 

a half a mile the distance I was out every Spire of Grass was covered with the 

Sand or Dust ... 23 August 1804 

Eolian transport was not mentioned again until 1805 when they were headed up 

the Missouri River in what is now western North Dakota and eastern Montana. 

Several entries bemoaned the wind and culminated in the following entries in April 

1805: 

... a cold morning at about 9 oClock the wind as usia/ rose from theN Wand 

continued to blow verry hard until/late in the evening ... 23 April 1805 

... The wind blew so hard during the whole of this day, that we were unable 

to move ... Soar eyes is a common complaint among the party. I believe it 

origenates from the immence quantities of sand which is driven by the wind 

from the sandbars of the river in such clouds that you are unable to discover 

the opposite bank of the river in many instances. the particles of this sand 

are so fine and light that they are easily supported by the air, and are carried 

by the wind for many miles, and at a distance exhibiting every appearance 

of a collumn of thick smoke. so penitrating is this sand that we cannot keep 

any article free from it; in short we are compelled to eat, drink, and breath 

it very freely ... 24 April 1805 

53 
54 Lewis and Clark's Observations and Measurements of Geomorphology and Hydrology, and Changes with Time 

Muddy Missouri 

A century and a half after Lewis and Clark's observation of the source of the mud in the Missouri 

River, Colby and others (1956, page 2) reiterated this observation in quantitative detail in their study 

of sedimentation in the Wind River Basin of Wyoming: "The [Rocky Mountain] area underlain by 

Precambrian rocks covers 14 percent of the basin, yields 59 percent of the water, and yields much 

less than 1 percent of the sediment. In contrast, the [riverbank] area underlain by rocks [sediments] 

of Quaternary age covers 16 percent of the basin, yields about 63 percent of the sediment, but only 

about 2.5 percent of the water." 

The suspended-sediment load near the mouth of the Missouri River was 320,000,000 tons per year 

before flood-control dams were built from 1953 to 1967 (Keown and others, 1986). After the dams 

were built, the suspended-sediment load was 86,000,000 tons per year, which is almost one fourth 

less than before the dams. Lewis and Clark report that precipitate of one pint of Missouri water 

weighed 80:65 grs. The meaning of the ":" is unclear, but assuming they meant about 80 grains per 

pint, then this would be a concentration of about 9,400 milligrams per liter. A recent (June 10, 1990) 

measurement of a sample of the suspended-sediment concentration made at high discharge of the 

Missouri River (similar to what Lewis and Clark may have encountered in 1804) at St. Charles, Missouri, was 2,300 milligrams per liter (Moody and Meade, 1993). This sample was 14 percent sand 

and 86 percent silt and clay or "mud." The total concentration in this recent sample is just about 

one-fourth less than the concentration estimated from Lewis and Clark's observations in 1804 . 

... at 11 oClock the wind rose and continued to blow verry hard a head from 

theN. W. until/4 oClock PM, which blew the Sand off the Points in Such 

clouds as almost Covered us on the opposit bank ... 2 7 April1805 

This phenomenon observed by Lewis and Clark is a smaller scale analog to that 

which built the great deposits of loess after the ice ages, but it is probably very rare 

today because of bank stabilization, which has narrowed the river and eliminated 

most sandbars (Dale Blevins, oral communication, 2002). Deposition from this 

type of transport was observed above the Great Falls of the Missouri River . 

... on the banks of the river there are many large banks of sand much elivated 

above the plains on which they ly and appear as if they had been collected in 

the course of time from the river by the almost incessant S. W. winds; they 

always appear on the sides of the river opposite to those winds ... 15 July 

1805 

They observed and described the sediment transport process that today is well 

known as lateral accretion and is characteristic of many alluvial rivers . 

... In every bend the banks are fa lling in from the Current being thrown against 

those bends by the Sand points which inlarges and the Soil I believe from unques-
Geomorphology 

tionable appearns. of the entire bottom from one hill to the other being the mud 

or ooze of the River at Some former Period mixed with Sand and Clay easily melts 

and Slips into the River, and the mud mixes with the water & the Sand is washed 

down and lodges on the points ... 5 August 1804 

The amount of suspended sediment in the Missouri made the river distinctive. 

Apparently some people thought it came from the Platte River, but Lewis thought 

otherwise when he observed the confluence of the Platte and Missouri Rivers: 

... The river Platte does not furnish the Missouri with it's colouring matter, as 

has been asserted by some; but it throws into it immence quanties of sand 

and gives a celerity to it's current, of which it does not abate untill it joins the 

Mississippi. The water of the Platte is turbid at all seasons 

of the year, but it is by no means as much so, as that of the 

Missouri; the sediment it deposits consists of small particals of 

white sand, while that of the Missouri is composed principally 

of a dark rich loam in much greater quantity ... Fort Mandan 

Miscellany, Moulton, 1987, v. 3, p. 348. 

They felt the source was the banks of the Missouri River itself: 

... The Muddiness of the Missouri is Caused by the Washing 

in of it's banks-within the rocky mountains the Water is 

C/ear ... Postexpeditionary Miscellany, Moulton, 1993, v. 8, 

p. 414. 

The Sandy River (Quick Sand River) with headwaters on Mount 

Hood had similar characteristics of the Platte River. After Clark 

explored the mouth of the Quick Sand River, he wrote: 

55 

... I arrived at the enterance of a river which appeared to 

Scatter over a Sand bar, the bottom of which I could See quite 

across and did not appear to be 4 Inches deep in any part; 

I attempted to wade this Stream and to my astonishment 

found the bottom a quick Sand, and impassable- I called to 

the Canoes to put to Shore, I got into the Canoe and landed 

below the mouth, & Capt Lewis and my Self walked up 

this river about 1112 miles to examine this river which we 

found to be a verry Considerable Stream Dischargeing its 

waters through 2 Chanels which forms an Island of about 

This view of the confluence of the Osage (left) 

and Missouri Rivers shows a sediment-laden 

Missouri. The amount of sediment is only a 

fraction of the the historical load. 

3 miles in length on the river and 1112 miles wide, composed of Corse Sand 

which is thrown out of this quick Sand river Compressing the waters of the 

Columbia and throwing the whole Current of its waters against its Northern 

banks, within a Chane/ of 112 a mile wide, Several Small Islands 1 mile up 
56 Lewis and Cla rk's O bservations and Measurements of Geomorphology and Hydrology, and Changes with Time 

Lahars 

The large quantity of sand in the Sandy River, Oregon, may have been 

produced by a lahar from Mount Hood. Radiocarbon dating of wood samples 

and dendrochronological work indicate that the Old Maid Eruptive Period 

on Mount Hood was between A.D. 1686 and 1806 (Cameron and Pringle, 

1986). Tree ring characteristics suggest a tree-damaging event around A.D. 

1794 (Cameron and Pringle, 1987). The expedition may have arrived soon 

after one of these lahars, which filled the channel and caused the river to 

overflow its banks. At present, the river has a boulder-armored bed, and the 

channel is 3 to 4 m deep, and its banks are not inundated by moderate spring 

or fall floods (Cameron and Pringle, 1987). Similar lahars came off Mount 

St. Helens after the 1980 eruption, down the Cowlitz River and into the 

Columbia River. The normal navigation channel in the Columbia River near 

the mouth of the Cowlitz River is 40 feet deep. This volcanic material from 

Mount St. Helens clogged the river, and the depth of the navigation channel 

was reduced to 15 feet (David Kresch, written communication, 2002). 

this river, This Stream has much the appearance of the River Platt: roleing 

its quick Sands into the bottoms with great velocity after which it is divided 

into 2 Chanels by a large Sand bar before mentioned ... A Mountain which we 

Suppose to be Mt. Hood isS. 85° E about 47 miles distant from the mouth 

of quick sand river .. .3 November 1805 

and later on the return trip Lewis added: 

Sergt. Pryar returned in the evening and reported that he had ascended the 

river six miles; that above the point at which it divides itself into two 

channels it is about 300 yds wide tho' the channel is not more than 50 yds 

and only 6ft deep. this is a large vollume of water to collect in so short a 

distance; I therefore think it probable that there are some large creeks falling 

into it from the S. W the bed of this stream is formed entirely of quicksand; 

it's banks are low and at preasent overflows. the water is turbid and current 

rapid .... several different tribes informed us that it heads at Mount Hood ... 1 

April1806 

Clark's observations relative to the Sandy River and Mount Hood are pertinent to 

the Cowlitz River and Mount St. Helens in 1980 (above). 

Quantitative measurements of the suspended-sediment concentration are few, but 

Clark makes this measurement downstream from the Kansas River: 

... The water we Drink, or the Common water of the missourie at this time, 

contains half a Comn Wine Glass of ooze or mud to every pint ... 21 June 1804 
Geomorphology 

and later they send back to Thomas Jefferson a sample described in the Fort 

Mandan Miscellany (Moulton, 1987, v. 3, p. 475) as: 

25. Precipitate of one pint of Missouri water weight 80:65 grs 

Upriver in North Dakota, the Current of the Missourie is less rapid & contains 

much less Sediment and the water of the Yellowstone is turbid, tho' dose not possess as much sediment as that of the Missouri. They observed some unusual type 

of suspended sediment near the Yellowstone River: 

... more Pumice Stone & Lava washed down to the bottoms and some Pumice 

Stone floating in the river ... 17 April 1805 

Samples of pumice stone were saved and sent back to Thomas Jefferson as samples 

62 and 67 described in the Fort Mandan Miscellany as: 

62 Specimen of the pummice Stone found amongst the piles of drift wood on 

the Missouri, Sometimes found as low down as the mouth of the osage river. 

I can hear of no burning mountain in the neighborhood of the Missouri or 

its Branches, but the bluffs of the River are now on fire at Several places, 

particularly that part named in our chart of the Missouri The Burning 

Bluffs. The plains in many places, throughout this great extent of open 

country, exhibit abundant proofs of having been once on fire- Witness 

the Speciments of Lava and Pummicestone found in the Hills near fort 

mandon67. A Speciment of Lava & pummice Stone found in great abundance on the 

Sides of the Hills in the Neighborhood of Fort Mandan 1609 miles above the 

mouth of the Missouri ... The tract of Country which furnishes the Pummice 

Stone seen floating down the Misouri, is rather burning or burnt plains than 

burning mountainsThe Missouri River was probably one of the best rivers in which to observe bedload transport. Lewis and Clark first noted one reach in the lower Missouri in 

June 1804 as one of the worst quick or moveing sand bars Which I have Seen. A 

day later, Clark described sand waves and possibly antidunes that move upstream 

(page 58, "Riverbed Forms"): 

... the river riseing, water verry Swift Passed a Creek on the L. S. passed 

between two Islands, a verry bad place, Moveing Sands, we were nearly 

being Swallowed up by the roleing Sands over which the Current was So 

Strong that we Could not Stem it with out Sales under a Stiff breese in 

addition to our ores ... 15 June 1804 

... the Bows man Peter Crousat viewed The water on each Side of the Island 

which presented a most unfavourable prospect of Swift water over roleing 

Sands which rored like an immence falls ... 21 June 1804 

57 

This pumice stone was a 

sample of sediment transported by the Missouri 

River and collected by 

Lewis and Clark. 

Sample from Academy of Natural Sciences 

of Philadelphia (Pumice stone: Seybert 

Collection, 534; Spamer and others, 2000). 
58 

Riverbed Forms 

Classification of bed forms is based on particle size, the method of sediment transport, 

and the flow resistance created by the bed 

forms. Some studies were done by Simons 

and Richardson (1966) in flumes. Their 

results depended in some degree on the size 

of the flume but paved the way for later studies in the field. 

Ripples are repetitive asymmetrical bed forms 

that have geometries related to the size of 

the material composing them (Yalin, 1972). 

They typically have heights that are small relative to the flow depth. The upstream surface 

(stoss side) of a ripple slopes gently upward 

to a crest, and the downstream surface (lee 

side) slopes steeply downward into the ripple 

trough. This pattern is repeated in a wavelike manner. Sediment rolls and hops up the 

gentle slope and avalanches down the steep 

lee side into the trough. Ripples do not affect 

the water surface above them. Some of the 

largest ripples (20 to 30 feet high and 200 to 

300 feet apart) have been identified (Pardee, 

1942; Weis and Newman, 1971) on the bottom of the ice age Lake Missoula. The ripples 

were formed about 12,000 years ago when 

Lake Missoula drained after the ice dam 

broke, releasing water at speeds of about 78 

feet per second or 58 miles per hour and in 

water depths exceeding 800 feet (Allen and 

others, 1986). 

Dunes also are repetitive asymmetrical bed 

forms, but in this case their heights are sufficient for them to interact with the surface of 

the water. This interaction, rather than their 

composition, sets their geometric properties. 

Dunes can grow up to one-third of the ave:rage flow depth (Mohrig and Smith, 1996), 

but more typically they have heights that 

are less than one-fifth of the water depth (J. 

Dungan Smith, oral communication, 1989). 

The dune form moves downstream as sediment 

is eroded from the gently sloping upstream side 

and deposited on the downstream side in the 

trough. Turbulence in rivers, initiated near the 

crests of the dunes, often rises to the water surface, creating boils that push the water surface 

slightly higher than the surrounding water. 

Plane bed is flat and, depending upon the water 

velocity, sediment can be stationary or moving. 

Geomorphologists recognize both upper and 

lower plane-bed regimes. The former exists when 

grains move by rolling but not by saltation. The 

latter exists when all sizes of the sediment composing the riverbed go into suspension. 

Antidunes are symmetrical bed forms that 

are coupled to the water surface. These features form when the sediment is transported 

as bedload and the mean velocity of the flow 

is approximately equal to the speed of surface 

waves such that the surface waves do not propagate upstream. The water is highest over the 

crest and lowest over the trough. Their heights 

and lengths depend on the mean flow velocity 

and the properties of the coupled surface wave. 

Antidune heights can equal about one-half the 

water depth. In contrast to dunes, sediment is 

deposited on the upstream sides and eroded 

from the downstream sides of antidunes such 

that the form of the antidune moves upstream or 

is stationary. The sediment always moves downstream. The antidunes grow until the associated 

surface waves reach the shapes at which they 

must break. The turbulence produced by breaking of the surface waves puts the very loosely 

compacted sediment composing the antidunes 

temporarily into suspension (J. Dungan Smith, 

written communication, 2002). The antidunes 

continue this cycle of forming, growing, and 

breaking as long as the flow velocity is greater 

than the speed of a surface wave. 
Dunes and 

superposed ripples 

Dunes 

Washed out 

dunes 

Plane bed 

Antidune 

standing waves 

Antidune 

breaking waves 

Bed forms 

,--Weak boil 

Flow resistance~ Water 

velocity~ 

Bed forms are shaped by flow resistance and water velocity in rivers. 

Source: The bed forms shown 1n column I were adapted from Simons 

and Richardson ( 1966).The generalized plot of flow resistance shown in 

column 2 was adapted from Simons and others ( 1973). 

59 
60 Lewis and Clark's Observations and Measurements of Geomorphology and Hydrology, and Changes with Time 

One of the best places to observe bedload transport was at the mouth of the Platte 

River in the summer during high flow: 

... The bed of the river Platte is composes almost entirely of white sand, 

the particles of which, are remarkably small and light; these collecting, 

from[form?] large masses, which being partially buoyed up, are hurryed 

along at the bottom by this impetuous torrent, with irresistible force; 

sometimes obstructed by each other, suddonly stop; and form large sandbars 

in the course of a few hours, which are again as suddenly dissipated to form 

others, and to give place perhaps to the deepest channel of the river ... Fort 

Mandan Miscellany, Moulton, 1987, v. 3, p. 348. 

Transport at the mouths of the Niobrara (Que Courre), White, Cheyenne, and 

Grand (We tar hoo) Rivers had similarities to and differences with that of the 

Platte River: 

... passed the mouth of the River [Niobrara] Que Courre (rapid R) on the 

L. S. and Came to a Short distance above, this River is 152 yards wide at 

the mouth & 4 feet Deep Throwing out Sands like the Platt (only Corser) 

forming bars in its mouth ... this river widens above its mouth and is devided 

by Sand and Islands, the Current verry rapid ... the colour like that of the Plat 

is light, .. .4 September 1804 

... Capt Lewis and my Self went up this river [White] a Short distance and 

Crossed, found that this differed verry much from the Plat or que Courre, 

threw out but little Sand, about 300 yard wide, the water confind within 150 

yards, the current regular & Swift much resemblig the Missourie, with Sand 

bars from the points a Sand Island in the mouth ... 15 September 1804 

... this river [Cheyenne] Comes in from the S W and is about 400 yards wide, 

the Current appears gentle, throwing out but little Sands ... 1 October 1804 

... passed the mouth of a River [Grand] called by the ricares We tar hoo on the 

L. S. this river is 120 yards wide, the water of which at this time is Confined 

within 20 yards, dischargeing but a Small quantity, throwing out mud with 

Small propotion of Sand ... 8 October 1804 

Draining the sand hills of central and western Nebraska, the Platte River and its 

tributaries and the Niobrara River later became, in the tradition of Lewis and 

Clark, outdoor laboratories for the study of bedload transport. The high proportion of sand relative to other sizes and the shallowness of the rivers made bedload 

transport particularly accessible to scientific and engineering studies (Colby and 

others, 1953; Hubbell and Matejka, 1959; Sayre and Hubbell, 1965; Smith, 1970, 

1971; Williams, 1978; Eschner and others, 1983; Karlinger and others, 1983; 

Kircher, 1983; and Mohrig and Smith, 1996). 
Geomorphology 

DEPOSITION 

Observations of bank erosion and deposition on point bars downstream have been 

described above (page 36, "Riffle Formation"). Generally, at high flows in the 

spring and early summer, the Platte and some other tributaries deposited sediment 

into the Missouri River channel which fed the notorious sandbars and islands 

downstream. At other times the larger river created backwater conditions and 

deposited sediment into the mouths of tributaries: 

... The Mississippi when full throws large quantitys of mud into the mouths 

of these rivers whose courents not being equal to contend with it's power 

become still or eddy for many miles up them the mud is thus deposited and 

as they are but comparitively short their courents subside before that of the 

Mississippi which when it dose subside and leave them free to act they have 

so small a quantity of water to discharge that it finds it's way to the river 

in a very small channel which it cuts through this mud; thus in a manner 

conscealing their magnitude from the passanger along the main river ... 25 

November 1803 

... after a delay of two hours we passed a narrow channel of 45 to 80 yds wide 

five miles to the mouth of (3) Nadawa River, This river Corns in from the 

North and is navagable for Perogues Some distance. it is about 70 yards 

wide a little above the mouth, at the mouth not So wide, the mud of the 

Gut running out of the Missourie is thrown and Settles in the mouth ... 8 July 

1804 

These last two journal entries describe one of many processes that are recognized 

today as flood-plain-forming depositional processes. Eolian transport (Bagnold, 

1954) is another and deposits sediment on the flood plain downwind from the 

river. Vertical accretion (Schumm and Lichty, 1963; Moody and others, 1999) 

deposits sediment on sandbars and snags and on the banks when they are liable 

some times to be overflowed. Lateral accretion (Wolman and Leopold, 1957; 

Nelson and Smith, 1989) was yet another process described above as Sand that 

The Missouri River at the confluence of the Niobrara River, Nebraska 

61 
62 Lewis and Clark's Observations and Measurements of Geomorphology and Hydrology, and Changes with Time 

lodges on point bars and builds flood plains at the same time the banks are falling 

in from the Current being thrown against those bends by the Sand points and the 

flood plain is recycled, moving the river and its flood plain laterally and downriver 

across the meander belt. Throughout the regional landscapes traversed by Lewis 

and Clark, their observations indicated that they saw the Missouri as a dynamic 

river which has Changd its Bead at different times and has anced run and now 

filled, up & growing with willows & Cottonwood with traces of the ancient beds 

of the river are visible in many places through the whole extent of this valley. 
III 

L EWIS and Clark measured the rise and fall of rivers, which can be related in 

some situations to their temperature measurements. For many streams and 

rivers they recorded the navigability, water color, saltiness, and the size of the bed 

material. They accurately measured the width of most streams they encountered, 

from 4 yards to more than 1,000 yards. They probably made the first velocity 

measurements of most of the major rivers they encountered and provided some of 

the first descriptions, excellent even by modern standards, of turbulent processes 

in these rivers. Part of Thomas Jefferson's instructions to Lewis stated that: 

... The object of your mission is to explore the Missouri river, & such principal 

stream of it, as, by it's course & communication with the waters of the 

Pacific Ocean ... (Bergon, 1989) 

'Runoff 

Lewis and Clark took initiative and expanded Jefferson's instructions to include 

observations of basic hydrology. This included measurements of the stage of the 

rivers over time to produce hydrographs (page 68). They made inferences about 

the relations between precipitation and runoff shown by the hydrograph-a basic 

hydrologic topic that is still being studied today. Lewis and Clark's observations 

of the hydrology provide us today with insight into the natural characteristics of 

many western rivers before these rivers were altered and controlled by engineering 

projects. They made observations, measurements, and inferences relative to different types of runoff: snowmelt in the mountains of Idaho, rain-on-snow phenomena creating flash floods, ice breakup on the Missouri and Mississippi Rivers, 

and summer thunderstorm rainfall and runoff. 

SNOWMELT 

They first made inferences about snowmelt based on the characteristics of the 

channel of the Sun River (Medecine River) just above the Great Falls: 

... medecine river, found it a handsome stream, about 200 yds. wide with 

a gentle current, apparently deep, it's waters clear, and banks which were 

formed principally of darkbrown and blue clay were about the hight of those 

of the Missouri or from 3 to 5 feet; yet they had not the appearance of ever 

Blackfoot River in Montana 

Photo: USGS 
64 Lewis and Clark's Observations and Measurements of Geomorphology and Hydrology, and Changes with Time 

r 

.,.""-Great Falls 

being overflown, a circumstance, which I did not expect 

so immediately in the neighbourhood of the mountains, 

from whence I should have supposed, that sudden and 

immence torrants would issue at certain seasons of the 

year; but the reverse is absolutely the case. I am therefore 

compelled to beleive that the snowey mountains yeald 

their warters slowly, being partially effected every day by 

the influence of the sun only, and never suddonly melted 

50 Miles down by haisty showers of rain ... 14 June 1805 

and later they recorded in their weather logs (below) the 

snowmelt runoff firsthand while waiting at Camp Chopunnish on the Clearwater 

River for the snow to melt in the Rocky Mountains during June of 1806: 

The hydrograph shows the 

1806 snowmelt peak occurring two weeks later than 

the median date of the peak 

runoff. 

... the river raised 6 inches in the course of yesterday and 1 foot 5 I. in the 

course of the last night. it is now as high as there are any marks of it's having 

been in the spring 1805.- at 10 A. M. it arrived at it's greatest hight having 

raised 11/2 inches from sunrise to that time. in the ballance of the day it fell 

7 inches. the natives inform us that it will take one more rise before it begins 

finally to subside for the season and then the passage of the mountains will 

be practicable ... 29 May 1806 

.. .from sunset on the 31st of May until/ sun rise on the 1st of June it rose 

Eighteen inches and is now as high as any marks of it's having been for 

several years past...31 May 1806 

... the Indians inform us that the present rise of the river is the greatest which 

it annually takes, and that when the water now subsides to about the hight it 

was when we arrived here the mountains will be passable. I have no doubt 

but that the melting of the mountain snows in the begining of June is what 

Hydrograph for Clearwater River at Camp Chopunnish 

Peak runoff 1961-2000* 

6----------~----------

Arbitrary 

--

river stage, 3------------

in feet 

measured by 

Lewis and Clark 

0----~-------~-------~ 

April May June 

*The vertical white bar is the 

median, May 24. The ends of 

the box are the 25th and 75th 

percentiles corresponding to 

May 13 and June I. The earliest 

and latest days for the peak 

runoff are April 21 and June 20. 
Hydrology 

causes the annual inundation of the lower portion of the Missouri from the 

1st to the Middle of July ... 2 June 1806 

... the river fell31!2 inches in the course of the day and raised 4 I. last night as 

[s]tated in the diary. this fluctuating state of the river no doubt caused by 

the influence of the sun in the course of the day on the snows of 

the mountains; the accession of water thus caused in the day dose 

not reach us untill night when it produces a rise in the river ... S 

June 1806 

While they waited, they measured the stage of the Clearwater River 

from May 30 through June 10 and observed the peak that occurred 

on June 5. Based on data for 1961 through 2000 (opposite), the 

average date for the peak runoff at a gaging site (Clearwater River 

at Spalding, Idaho) downstream from Camp Chopunnish was May 

24. Thus, in 1806 the snowmelt runoff was almost 2 weeks later 

than the present-day median date. This does not reflect a change in 

climate but simply the variability of the weather. Lewis and Clark 

encountered a later than usual snowmelt, even for the early 1800s. 

It is also possible that they encountered a second snowmelt peak (see 29 May 

1806 excerpt). This is common for the Clearwater River and may be a result of 

snowmelt from different elevations within the Clearwater basin (Steve Lipscomb, 

written communication, 2002). 

RAIN ON SNOW 

Once again Lewis and Clark made a conjecture about the hydrology based on the 

character of the river channel: 

... passed three streames today which discharged themselves on the Lard. side; 

the first of these we call little dry creek it contained some water in standing 

pools but discharged none, the 2ed 50 yards wide no Water, we called it Big 

dry Creek, the 3rd is bed of a conspicuous river 200 yards wide which we 

called little dry river; the banks of these streams are low and bottoms wide 

with but little timber, their beds are almost entirely formed of a fine brown 

sand intermixed with a small proportion of little pebbles, which were either 

transparent, white, green, red, yellow or brown. these streams appeared to 

continue their width without diminution as far as we could perceive them 

which with rispect to the river was many miles, they had recenly discharged 

their waters. from the appearance of these streams, and the country through 

which they passed, we concluded that they had their sauces in level/ow dry 

plains ... that the rains in the spring of the year <in a few day> suddonly melts 

the snow at the same time and causes for a few days a vast quantity of water 

which finds it's way to the Missouri through those channels ... 6 May 1805 

65 
66 

This ice jam on the Platte 

River (February 2003) is 

probably typical of the 

ones observed by Lewis 

and Clark. 

Lewis and Clark's Observations and Measurements of Geomorphology and Hydrology, and Changes with Time 

These dry channels, in what is now Montana, were features unexpected by Lewis 

and Clark who, like most Americans of that time, were accustomed to eastern rivers 

that usually flowed all year and in which the flow usually increased downstream: 

... today we passed the bed of the most extraordinary river that I ever beheld. 

it is as wide as the Missouri is at this place or 112 a mile wide and not 

containing a single drop of runing water; some small standing pools being 

all the water that could be perceived. it falls in on the Lard. side. I walked 

up this river about three miles ... the bank are low and abbrupt, seldom more 

than 6 or eight feet above the level of the bed, yet show but little appearance 

of being overflown ... it had the appearance of having recently discharged it's 

waters; and from the watermark, it did not appear that it had been more 

than 2 feet deep at it's greatest hight ... 9 May 1805 

... Those dry Streams which are also verry wide, I think is the Conveyance of 

the melted Snow, & heavy rains ... 9 May 1805 

... this we call Teapot Creek, it affords no water at it's mouth but has runing 

water at some small distance above, this I beleive to be the case with many 

of those creekes which we have passed since we entered this hilley country, 

the water is absorbed by the earth near the river and of course appear dry; 

they afford but little water at any rate ... 23 May 1805 

ICE BREAKUP 

While the expedition was at Camp Dubois opposite the mouth of the Missouri 

River, Clark measured air temperature, river stage, and ice conditions on the 

Missouri and Mississippi Rivers. Running Ice was observed on Thursday 

December 22, 1803, on the Mississippi River, which seems to have been frozen 

over by January 4, 1804: 

... a Cold Clear morning, the river Covered with Ice from the Missouri, the 

Massissippi above frosed across, the Wind from the West, The Thermometer 

this morning at 19• below freesing .. .4 January 1804 

Photo: Nebraska Department of Natural Resources 
Hydrology 67 

Camp Dubois 

... The ice run for Several days in Such quantities 

100 

that it was impossible to pass the River [Mississippi] ... 

River stagE 

in och s 

or 

Air temperature, 

50 

in degrees Fahrenheit 

4 PM. 

Sunrise 

Measurements of air temperature, river stage, and ice conditions at Camp Dubois opposite the mouth of the Missouri 

River shows how fluctuation 

0 

Feb Mar 

1804 

Apr May 

in the weather often causes 

flutuation in river stage and 

ice conditions. 

Temperature measurements were made carefully. The thermometer was put on 

the N. Side of a large tree in the woods and they described their methods in their 

weather log of January 1804 (Moulton, 1986, v. 2, p. 169): 

.. . By two experiments made with Ferenheit's Thermometer which I used in 

these observations, I asscertained it's error to be 11 o too low or additive +- I 

tested it with water and snow mixed for the friezing point, and boiling water 

for-the point marked boiling ... 

Absolute temperatures are uncertain, but relative temperatures would be reliable. 

They measured the temperature twice each day, at sunrise and at 4 P.M. In January 

1804, they begin to record this and other weather observations and river changes 

in a weather log for each month. During the last 4 days in January the temperature 

at sunrise averaged 13.2°F and at 4 P.M. it averaged 18oF. The ice conditions from 

January 28 to January 31, 1804, were: 

... Some floating Ice in the River ... 

... the river rise a little no Ice ... 

... but little Ice running this morng .. . 

... some Ice running this morning .. . 

Based on their measurements, fluctuations in the weather often caused fluctuations 

in river stage and also the ice conditions (above). 
68 

River Hydrographs 

The annual hydrograph is a plot of the stage or 

discharge of the river through the year. The hydrographs for the Ohio, Missouri, and Columbia 

Rivers are different because they drain different 

precipitation regimes. Stage is measured above 

some fixed datum (local or sea level) and indicates the height of the water but is not equal to the 

depth. In general, the mean velocity of the river 

is not directly proportional to the depth, but it is 

proportional to the discharge at a fixed location. 

Average annual stage hydrograph for the Ohio River at Louisville, Kentucky ( 1876-1895) 

River stage, 

in feet 

Orange arrow indicates travel dates of 

Lewis and Clark. 

A peak in February may reflect winter rainstorms 

in the southern part and snowmelt from the 

northern part of the Ohio River drainage basin. 

20----------------r---------

Many minor peaks may reflect winter rains in the 

southern parts of me basin Oanuary peak) or spring 

rainstorms throughout the basin (March-April peak). 

I 

Lewis and Clark traveled during a low-water 

period in October and apparently encountered even lower water than the average 

shown. 

Oct Nov Dec Jan Feb Mar Apr May June July Aug Sept 

Average annual stage hydrograph for the Missouri River at Omaha, Nebraska ( 1931-1950) 

River stage, 

in feet 

The peak in June and july represents the 

snowmelt from the Rocky Mountains. 

The peak in March and April represents I 

the snowmelt from low-elevation areas. 

I 10 -------------------7 , cc 

Site of Omaha 

i 

Lewis and Clark were at Camp Dubois during the first peak, which was associated with 

the ice breakup. They struggled upstream 

against the second peak and arrived at 

Council Bluffs just upriver from what would 

be the city of Omaha about july 28, 1804. 

Low water is in October and November, 

and Lewis and Clark encountered this part r of the annual hydrograph while traversing 

1 between what are now Pierre, South Dako0 --ii--'--T---.--,--,------,---,---,-'---,--,------,---,---i-- ta, and Bismarck, North Dakota, from 

Oct Nov Dec Jan Feb Mar Apr May June July Aug Sept about September 15 to October 27, 1804. 

Average annual stage hydrograph for the Columbia River at The Dalles, Oregon (1879-1896) 

River stage, 

in feet 

Most of the parts of eastern Washington 

30 __ and Oregon drained by the Columbia l 

River are arid lands, so the one annual 

peak in june represents the snowmelt 

- from the Rocky Mountains. 

20-------------

Passed The Dalles Passed The Dalles 

going upstream 

II I 0--,l~-+~-~lr---.I--,-'I-L,I-L'Ir---.l--,--l -,1--,1-'1~ 

going downstream 

Oct Nov Dec Jan Feb Mar Apr May June July Aug Sept 

The Dalles is on the eastern side of the Cascades, so the prolonged winter rains that 

Lewis and Clark endured at Fort Clatsop at 

the mouth of the Columbia River are not part 

of this hydrograph. Lewis and Clark entered 

the Columbia River at the mouth of the Snake 

River on October 18, 1805, passed The Dalles 

on about October 24, 1805, and reached the 

tidewater area of the Columbia River a few 

days later. 
Hydrology 

Temperatures rose from the end of January until mid-February, and the river stage 

rose bringing increasing quantities of ice. They listed the conditions from February 

4 through February 6, 1804, as: 

... the River Covered with large Sheetes of Ice from both rivers .. . 

... emmence quantities of ice runing some of which 11 Inches .. . 

... river riseing & Covered with Small Ice ... 

and with the sudden rise on February 9, 1804: 

... the river raised 2 feet, large quantity of drift ice from Misso[uri] ... 

Then the temperature in February decreased, the stage decreased, but no ice 

observations were recorded in the weather log. An increase in temperature in midMarch probably resulted in the spring ice breakup because the stage reached a 

maximum and then decreased rapidly (page 67). From the Weather Log on March 

19, 1804: 

... the ice run for Several days in Such quantities that is was impossible to pass 

the River [Mississippi]. .. 

Lewis and Clark repeated these ice observations and measurements during the 

winter of 1804-05 at Fort Mandan. On October 31, 1804, Lewis noted that the 

river being very low and the season so far advanced that it frequently shuts up with 

ice in this climate. By November 13, the river has every appearance of closing for 

winter, and the weather log again showed daily river changes and temperatures at 

sunrise and 4 P.M (below). For the Missouri River near Fort Mandan, where the 

Fort Mandan 

ISO 

... Ice stoped runing owing 

to Some obsticle above... . .. Ice is passing in 

great quantities ... 

100 

69 

The following winter 

... river is falling fast... measurements were 

RIVEr sta~e. 

or SO 

Air temperature, 

in degrees Fahrenheit 

0 

-50 

repeated at Fort Mandan on 

the Missouri River. Starting 

in late November there is 

---n~--flr- ---T.-.,----t---t...,.--.....,.-- r:-.::-\---tt.-dlr;f.IJ\II.,------32° F a drop in temperature and 

Nov Dec Jan Feb 

1804 

Mar Apr 

1805 

unexplainable rise in stage. 

By mid-March the breakup 

of the ice corresponds 

to the temperature rising 

above 3rF. 
70 Lewis and Clark's Observations and Measurements of Geomorphology and Hydrology, and Changes with Time 

temperature was much colder (-4YF at sunrise on December 17, 1804), the river 

stage does not appear correlated with air temperature. Without knowing exactly 

where the stage was being measured and how that water was connected to the 

main channel, one cannot explain why the river stage should increase while the 

temperature was generally decreasing during January 1805. However, as the temperature rose above freezing, the river stages definitely increased, resulting in the 

ice breakup followed by an ice jam: 

... The ice broke up in Several places in the evenig broke away and was nearly 

takeing off our new Canoes ... 25 March 1805 

... river choked up with ice opposit to us ... the ice gave way in the river 

about 3 P. M. and came down in immense sheets very near distroying our 

perogues ... 26 March 1805 

... ice running the [river] Blocked up in view for the Space of 4 hours and gave 

way leaveing great quantity of ice on the Shallow Sand bars ... 27 March 1805 

... the ice Stoped running owing to Some obstickle above ... 28 March 1805 

on March 29, 1805: 

... The obstickle broke away above & the ice came dow in great quantites the 

river rose 13 inches the last 24 hours ... 

on March 31, 1805, ... not much ice floating ... , and finally on April2, 1805, Clark 

noted that the river is falling fast. 

'River Characteristics 

NAVIGABILITY, COLOR, BED MATERIAL 

Navigability of the rivers was uppermost in the minds of Lewis and Clark. They 

described this river characteristic (opposite page) in terms of the type of water 

craft (boat, bateau, pirogue, or canoe) that could navigate the river; the distance 

upstream in miles, leagues, or to a landmark; and in some cases the depth of the 

water in feet . 

... the yellow Stone river is navigable at all seasons of the year, for boats or 

perogues to the foot of the Rocky Mountains, near which place, it is said 

to be not more than 20 miles distant from the most southernly of the three 

forks of the Missouri, which last is also navigable to this point. if Indian 

information can be relied on, this river waters one of the fairest portions of 

Louisiana ... Fort Mandan Miscellany, Moulton, 1987, v. 3, p. 364. 

River color was apparently not noteworthy for the eastern tributaries (generally 

east of 100th meridian), but the color of western tributaries seems to have had 
Hydrology 

Navigability, channel width, water color, and bed material for some rivers observed by Lewis and Clark. 

Columbia Clearwater 

Mud 

cobbles

G~I, So"d or rocks 

This example indicates a 

width. of 500 yards. a 

yellow water color, and 

bed material, which is 

mostly sand, some gravel, 

and a little mud. 

CHANNEL WIDTH, WATER COLOR, 

and BED MATERIAL 

I. The area of circle is proportional to the 

channel width. 

2.The color of the large circle indicates the 

color of the water. White indicates no 

color mentioned in the journals. Random 

quotes under stream name are from 

Lewis and Clark. 

3. Description of the bed material is determined by the position of the orange circle 

within the black triangle. The three apexes 

of the triangle diagram represent I 00 percent mud, I 00 percent sand, or I 00 percent gravel, cobbles, and rocks. 

RIVER NAVIGABILITY 

Boat 

-1- Canoe and pirogues. Grey line indicates falls. 

Not navigable 

Yellowstone 

" ... yellow-white ... " 

200 Kilometers 

200 Miles 

71 
72 Lewis and Clark's Observations and Measurements of Geomorphology and Hydrology, and Changes with Time 

This view (April 1999) looking downstream 

shows the confluence of the Milk and 

Missouri Rivers in Montana. The water of the 

Milk " ... possesses a peculiar whiteness". 

Airphoto-jim Wark 

enough variation to have caught their eyes when they passed 

and explored them. It often gave them clues to the source of a 

river (page 7, 3 June 1805 and page 9, 29 July 1806) . 

... the water of this river possesses a peculiar whiteness, 

being about the colour of a cup of tea with the admixture 

of a tablespoonful/ of milk. from the colour of it's water we 

called it Milk river ... 8 May 1805 

... the otter are now plenty since the water has become sufficiently clear for 

them to take fish ... 12 July 1805 

They also noted the location of salt springs and licks. This was again according to 

Jefferson's instructions to include "Other object worthy of notice will be ... salines 

& mineral waters" (Bergon, 1989): 

... this River [Petite Saline Creek in Missouri] is about 30 yds. wide, and has 

So many Licks & Salt Springs on its banks that the Water of the Creek is 

Brackish, one Verry large Lick is 9 ms. up on the left Side the water of the 

Spring in this Lick is Strong as one bushel of the water is said to make 7 lb. 

of good Salt ... 6 June 1804 

... the water of those Springs are not Strong, Say from 4 to 600 Gs. of water for 

a Bushel of Salt ... 7 June 1804 

... The Waters of this river is Clear, and a Salmon may be Seen at the deabth of 

15 or 20 feet ... 17 October 1805 

and the temperature of the water: 

... the Fog appears to owe it's orrigin to the difference of temperature between the 

air and water the latter at this seson being much warmer than the former; the 

water being heated by the summer's sun dose not undergo so rapid a change 

from the absence of the sun as the air dose consiquently when the air becomes 

most cool which is about sunrise the fogg is thickest and appears to rise from 

the face of the water like the steem from boiling water ... 1 September 1803 
Hydrology 

... Verry foggy this morning. Thermometer 63 o Ferrenheit, immersed the 

Thermometer in the river, and the murcury arose immediately to 7 So or 

summer heat so that there is 12 o difference is sufficient to shew the vapor 

which arrises from the water .. .3 September 1803 

... Morning foggy, obliged to wait. Thermometer at 63°- temperature of the 

river- water 73° being a difference of ten degrees, but yesterday there was 

a difference of twelve degrees, so that the water must have changed it's 

temperature 2d in twenty four hours, coalder; at 1/4 past 8 the murcury 

rose in the open air to 68o the fogg dispeared and we set out; the difference 

therefore of So in temperature between the warter and air is not sufficient to 

produce the appearance of fogg .. .4 September 1803 

... Thermometer in the air to stand at 7r water 73°- the fogg continued 

even with small difference between the temperature of the air and water ... 6 

September 1803 

In the Rocky Mountains, they used temperature to determine the expedition's route: 

... it's [Beaverhead River] water is much warmer then the rapid fork [Big Hole 

River] and it's water more turbid; from which I conjecture that it has it's 

sources at a greater distance in the mountains and passes through an opener 

country than the other. under this impression I wrote a note to Capt Clark, 

recommending his taking the middle fork povided he should arrive at this 

place before my return, which I expect will be the day after tomorrow. this 

note I left on a pole at the forks of the river .. .4 August 1805 

and the character of the country: 

... The water of this river [Tongue River] is nearly milk worm very muddy and 

of a dark lightish brown Colour ... tho' I believe that the Country back thro' 

This view (May 1999) looking upstream 

shows t he confluence of t he Yellowstone and 

Missouri Rivers in Montana. The Yellowstone 

is "navigable at all seasons of the year, for 

boats or perogues to the foot of the Rocky 

Mountains ". 

Airphoto-Jim Wark 

73 
74 

This view of the Missouri 

River looks southeast 

just north of Bismarck, 

North Dakota. 

Photo: USGS. 200 I 

Lewis and Clark's Observations and Measurements of Geomorphology and Hydrology, and Changes with Time 

which this river passes is an open one where the water is exposed to the Sun 

which heats it in its passage ... 29 July 1806 

Lewis and Clark collected a sample of bed material which was sent back to 

Jefferson in 1805 (Moulton, 1987, v. 3, p. 4 72). This sample, along with other mineral samples, may have reached the Academy of Natural Sciences in Philadelphia, 

Pennsylvania. Over the years, many samples apparently lost their labels; consequently, they were thrown out. Two samples remain: a piece of slag and a piece of 

pumice (page 57). Lewis and Clark also described the bed material of many rivers. 

For example, they used the bed-material characteristics to predict the character of 

the country surrounding the Little Missouri River: 

... the colour of the water, the bed of the river, and it's appearance <of this 

river> in every respect, resembles the Missouri; I am therefore induced to 

believe that the texture of the soil of the country in which it takes it's rise, 

and that through which is passes, is similar to the country through which the 

Missouri passes ... 12 April1805 

and remarked on the downstream fining of bed material in the Yellowstone River: 

... the bed of this river is almost entirely composed of loose pebble, nor is it's 

bed interrupted by chains of rock except in one place and that even furnishes 

no considerable obstruction to it's navigation. as you decend with the river 

from the mountain the pebble becomes smaller and the quantity of mud 

increased until/ you reah Tongue river where the pebble ceases and the sand 

then increases and predominates near it's mouth .. .3 August 1806 

Clark made the observation but did not conjecture why the size of the material 

decreased in the downstream direction. Frisi (1762) mentioned that Guglielmini 

felt the size decreases because "stones, impelled by the impetuosity of the water, 
Hydrology 

rolling over and striking each other, must break and continually wear away." 

However, Frisi reflects a still-persistent religious opinion in the 18th century "that 

round stones, gravels, and sands, are substances originally prepared by nature, 

and spread all over the globe." Later observers of downstream fining of sediment in rivers have also concurred with Guglielmini's idea of abrasion (Shaw and 

Kellerhals, 1982). Others have proposed the selective transport of finer grains 

(Paola and Seal, 1995) and finer input by tributaries downstream (Pizzuto, 1995). 

In the Yellowstone River, however, it is difficult to attribute downstream fining to 

any process of progressive hydraulic sorting of coarser materials introduced in the 

upper river basin because of the continual introduction of gravels from the erodible terrace deposits that flank much of the course of the river. 

J{ycfraufic (jeometry 

Lewis and Clark measured and noted the channel widths of virtually every stream 

they encountered- many more streams than those for which they listed the navigability, color, or bed material. Their measurements were of bankfull width-the 

channel width from bank to bank-and not just measurements of the width of 

the mouth or of the water. Lewis and Clark seemed to have realized that there 

was a great variability of discharge and perhaps cogitated on which discharge was 

important in determining channel geometry . 

... I measure the river from bank to bank on the ice and make it 500 yards ... 12 

December 1804 

Lewis and Clark often explored tributaries some distance upstream to determine 

their true character: 

... I walked on shore and acended this river 

about a mile and a half in order to examine 

it. I found this river about 100 yds. wide from 

bank to bank, the water occupying about 7 5 

yard ... Cap. C who ass ended this R. much 

higher than I did has <thought proper to> call 

it ]udieths River ... 29 May 1805 

... This morning I dispatched Joseph Fields up 

the yellowstone river with orders to examine it 

as far as he could conveniently and return the 

same evening; .. the bottom land on the lower 

side of the yellowstone river near it's mouth for 

about one mile in width appears to be subject 

to inundation ... the bed of the yellowstone river 

is entirely composed of sand and mud, not a 

/ 

M 0 N T A N A 

f '{~ (:' ~ ' 

'\o""o;_, 

/ 

~ <l,o;SJ ~ 

WYO MI NG 

.J 

~ .... 

·!: 

'-./ 

0 

75 

so 
76 Lewis and Clark 's Observations and Measurements of Geomorphology and Hydrology, and Changes with Time 

stone of any kind to be seen in it near it's entrance. Capt Clark measured 

these rivers just above their confluence; found the bed of the Missouri 520 

yards wide, the water occupying 330. it's channel deep. the yellowstone 

river including it's sandbar, 858 yds. of which, the water occupyed 297 

yards, the depest part 12 feet; it was falling at this time & appeard to be 

nearly at it's summer tide ... 26 Apri/1805 

Often along the Missouri River, they clearly differentiated between flood-plain 

width, bankfull width, and the width of the water surface: 

... this river [Moreau River in South Dakota] whin full is 90 yards wide the 

water is at this time Confined within 20 yards ... ! walked up this river a 

mile .. .7 October 1804 

... (2) passed the mouth of a River called by the ricares We tar hoo [Grand 

River in South Dakota] on the L.S. this river is 120 yards wide, the water 

of which at this time is Confined within 20 yards ... 8 October 1804 

... passed the mouth of (1) Ia Boulet (or Cannon Ball River) about 140 yards 

wide on the L. S .... above the mouth of this river Great numbers of Stone 

perfectly round with fine Grit are in the Bluff and on the Shore, the river 

takes its name from those Stones which resemble Cannon Balls.- The water 

of this river is Confined within 40 yards ... 18 October 1804 

and along the Yellowstone River: 

... draw up the Canoes and take Shelter in an old Indian Lodge above the 

enterance of a river which is nearly dry it has laterly been very high and 

Spread over nearly 1/4 a mile in width. its Chane/ is 88 yards and in this 

there is not more water than could pass through an inch auger hole. I call it 

Yorks dry R .... after the rain and wind passed over I proceeded on at 7 Miles 

passed the enterance of a river [Powder River] the water of which is 100 yds 

wide, the bead of this river nearly 1/4 of a mile this river is Shallow and 

the water very muddy and of the Colour of the banks a darkish brown. I 

observe great quantities of red Stone thrown out of this river that from the 

appearance of the hills at a distance on its lower Side induced me to call this 

red Stone river .. .30 July 1806 

Of the later writers who remarked on this phenomenon, most notable is perhaps 

Struthers Burt, who wrote of the Powder River: 

"A mile wide and an inch deep is the acidly affectionate description used by 

those who are its intimates, and although the Powder is by no means a mile 

wide, and although it is considerably over an inch deep, the phrase possesses 

the exaggerated truth common to folk descriptions; an exaggerated truth 

conveying a picture clearer than exactness." (Burt, 1938) 
Hydrology 

Lewis and Clark recognized seasonal effects in the spring of 1805: 

... we found that it [White Earth River or Little Muddy River] contained more 

water than streams of it's size generally do at this season. the water is much 

clearer than that of the Missouri. the banks of the river are steep and not 

more than ten or twelve feet high; the bed seems to be composed of mud 

altogether. the salts which have been before mentioned as common on the 

Missouri, appears in great quantities along the banks of this river, which are 

in many places so thickly covered with it that the appear perfectly white. 

perhaps it has been from this white appearance of it's banks that the river 

has derived it's name ... 22 April 1805 

and again in 1805: 

... passed Dearborne's river at 3 m. this stream comes form 

the S. W out of the mountains which are about 5 Ms. 

to our left. the bed of the river is about 100 yds. wide 

tho' the water occupys only about 30 yds. it appears to 

spread over it's bottoms at certain seasons of the year 

and runs a mear tarrant tearing up the trees by the roots 

which stand in it's bottom ... 18 July 1805 

After more than a year in the field measuring and describing 

river channels, Clark took an evening walk and essentially 

inferred a relation between the Size or width of the rivers 

he had been measuring and the drainage area of those rivers 

or the extent of country. His observations suggest a relation 

between the drainage area and the quantity of water or discharge of the river: 

... I continued my walk on Shore after dinner, and arrived at the mouth of a 

river on the St. Side, which appeared to be large, and I concluded to go up 

this river a few miles to examine it accordingly I Set out North 1 mile thro 

wood or timbered bottom, 2 miles through a butifullleavel plain, and 1 mile 

over a high plain about 50 feet higher than the bottom & Came to the little 

river, which I found to be a butifull clear Stream of about 100 yds. from 

bank to bank, I waded this river at the narrowest part and made it 112 Steps 

from bank to bank ... This river we call Porcupine from the great number of 

those anamals found about it's mouth .... This river from its Size & quantity of 

water must head at no great distance from the Saskashawan .. .3 May 1805 

and later a similar inference about the Milk River 

... from the quantity of water furnised by this river it must water a large 

extent of country; perhaps this river also might furnish a practicable and 

advantageous communication with the Saskashiwan river ... 8 May 1805 

77 

The Dearborn River, Montana 

runs high during spring runoff. 

Photo courtesy of Big Sky Fishing. Com 
78 Lewis and Clark's Observations and Measurements of Geomorphology and Hydrology, and Changes with Time 

After a year of measuring 

rivers, Clark inferred a relation between the width 1,000 

River widths measured by Lewis and Clark 

plotted relative to drainage areas compiled in 2000 

• 

of rivers and the drainage 

area. His inferences were 

confirmed 150 years later 

as shown by the blackline based on data from 

Leopold and Maddock 

( 1953) and Hack ( 1957). River width, 

in yards 

100 

10 

Mountain streams 

• 

• • 

• 

• 

••• • / • 

Plains streams 

The logarithmic scale allows very 

small values of river width and 

drainage area to be shown as well 

as very large values. 

100 10,000 1,000,000 

Drainage area, in square miles 

Lewis and Clark measured the widths but did not have actual drainage areas to 

test the relation that they were using to infer the extent of country. They made 

about 275 width measurements of rivers, streams, and creeks ranging from 4 to 

875 yards. Some of the larger rivers (Missouri, Yellowstone, and Columbia) were 

measured in several locations. Drainage areas were compiled in 2000 for 191 

of these rivers from published reports and from maps with scales of 1:250,000, 

1:500,000, and 1:3,500,000. Some of the smaller streams and creeks could not 

be identified with present-day streams and creeks, so the drainage area was not 

determined. The data were divided into two groups: presumably low-gradient or 

plains channels (downstream from the mouth of the Yellowstone River) and highgradient or mountainous channels (upstream from the mouth of the Yellowstone 

River and those rivers in the Columbia River Basin). The relations for the plains 

and mountainous channels were basically the same (see graph above). The relation 

for plains channels was 

width = 4.0 x drainage area

036, R2 = 0.71 

and the relation for the mountainous channels was 

width = 3.6 x drainage area0.4 1

, R2 = 0.60 

where the width is in yards, the drainage area is in square miles, and R2 is the coefficient of determination. About 150 years after Lewis and Clark's measurements, 

Leopold and Maddock (1953) and Hack (1957) confirmed these inferences with 

published data. Leopold and Maddock (1953 ) list 105 measurements (some of 
Hydrology 

which were the same channels measured by Lewis and Clark) and Hack lists 91 

measurements (for mostly small streams in Virginia and Maryland). The plot of 

their combined 196 measurements is similar to the plot of the Lewis and Clark data 

(black line in graph opposite); the relation for their combined data is also similar: 

width= 4.8 x drainage area

0

·

31 , R2 = 0.75 

Ye{ocity .1vleasurements 

The velocity of the Missouri River was an immediate concern to Lewis and Clark 

as they worked upstream against the current created by the annual spring runoff. 

Many journal entries give qualitative measures of the velocity of the current. They 

begin on May 15, 1804, as Lewis and Clark entered the mouth of the Missouri 

River, and no two entries are identical: 

... the water excessively rapid ... verry hard water ... the water excessively Swift 

to day ... the Currents verry Swift ... the current exceedingly rapid ... Some 

Swift water ... we found the water excessively hard for 12 Miles ... the Current 

exceedingly Strong ... the immence Current & falling banks on the S.S ... water 

very swift ... 15 May to 15 June 1804 

Clark made the first quantitative measurements of the velocity while some of the 

expedition were making tow ropes at Rope Walk Camp: 

... The Current of the River at this place is a Stick will float 48 poles 6 feet in 

the rapidest part in 23 Seconds, further out is 34, Still further 65-74-78 

& 82 are the Trials we have made ... 17 June 1804 

Unfortunately, it is not entirely clear if he meant 48 pole and 6 feet or 4.8 pole and 

6 feet or perhaps 48 fathoms as mentioned below. If the first option of 48 poles 6 

feet is used, then the total distance would have been 798 feet and the velocity would 

have been 23.6 mph (miles per hour), which is unreasonable even for the Missouri 

River. Clark in previous measurements would write the tenths of a pole as 8/1 0; 

however, if it is 4.8 poles and 6 feet then the velocity of the river is 3. 7 ft/s or 2.5 

mph, which is reasonable but perhaps on the slow side. If one assumes the third 

option, 48 fathoms (and the 6 feet was meant to define a fathom), then the velocity 

is 18.4 ft/s or 12.5 mph. Later measurements were made by the U.S. Geological 

Survey at Waverly, Missouri (1928-30), which is near the site of Clark's measurements (Dale Blevins, written communication, 2002). The maximum velocity was 

12.5 ft/s corresponding to a discharge of about 230,000 ft3/s so that the third 

option seems possible. A possible argument against 48 fathoms is that Clark mentions a Stick will float rather than using a logline (as he does later), so he may have 

made measurements from the shore where he would probably measure in poles (a 

land unit of measure) rather than in fathoms (a nautical unit of measure). We will 

79 
80 

River Velocities 

River velocities depend upon the slope of the 

channel, the depth of water, and the roughness 

of the bottom material. The velocity is slowest 

near the bottom and increases as the distance 

increases above the bottom. The maximum 

velocity is not necessarily at the surface, but 

somewhat below the surface. This subsurface 

maximum was carefully measured on the Lower Mississippi River by Humphreys and Abbot 

(1876) in the 1860s repeating many measurements using drift buoys, which were timed as 

the river velocity carried them downstream for 

a specific distance. Normally, velocity is only 

measured at one fixed location relative to the 

bottom of the river. However, Savini and Bodhaine (1971) made a unique set of simultaneous 

measurements of velocity at 12 fixed locations 

above the bottom. These measurements provide 

a good example of the vertical and horizontal 

structure of river velocities. The depth-averaged 

velocity is approximately equal to the velocity 

at 0.6 of the water depth below the surface. It 

is also approximately equal to the average of 

the values at 0.2 and 0.8 of the water depth. 

This is the method used by the U.S. Geological 

Survey when measuring and calculating the 

discharge of a river (Rantz and others, 1982). 

Sometimes only surface velocity measurements 

can be made and the depth-averaged velocity is 

estimated to be 0.86 times the surface velocity 

(Rantz and others, 1982). The mean velocity 

of the entire river is calculated by dividing the 

calculated discharge by the cross-sectional area 

of the river. 

Velocity structure for the Columbia River. 

(Measurements were made at the Hood River Bridge, Oregon, on June 5, 1961 .) 

The most rapid change in velocity is in 

the first I 0 feet above the bed where 

bed resistance produces a drag on the 

flow. Above that depth, the velocity 

slowly increases to 4.73 feet per 

second just 3.2 feet below the surface. 

The most rapid change in near-surface 

velocity (3.2 feet below the surface) is 

near the banks where bank resistance 

produces a drag on the flow. The 

effect of depth can be seen near the 

left bank where the depth gradually 

decreases and the velocity decreases. 

0 

a 

'a 

<a 

:!a 

tJ 'la ~l:>t~. •I~ 

sa ~~t 

Go 

NOTE: The vertical scale for depth is exaggerated relative to 

the horizontal scale for distance across the river from 

the left bank. Rivers are really very thin ribbons of 

flowing water. Data from Savini and Bodhaine ( 1971 ). 
Hydrology 

probably never know what he meant, but he seems to have been making the measurements at different distances from the shore along the outside of a bend where 

the velocity would be greatest. The velocities decrease with distance away from 

him and are only 1 ft/s or 0.7 mph (assuming the 4.8 pole option) at the farthest 

location, which may have been in shallow water over a point bar (see opposite 

page). Later, on July 17 and 18, he made additional measurements: 

... The Common Current taken with a Log runs 50 fathen in 40"-Some places 

much Swifter in 30" and even 20 Seconds of time ... 17 July 1804 

... Measured the Current and found that in forty one Seconds it run 50 

fathoms ... 18 July 1804 

These measurements give surface point velocities ranging from 7.3 to 15.0 ft/s or 

5.0 to 10.2 mph. This set of measurements appears to have been made from a boat 

using a log line (page 12, "Instruments"), probably while the boat was anchored 

in the river. However, if they made the measurements from a moving boat, then the 

velocity of the boat needs to be subtracted. At this time the expedition was making 

about 18 to 20 miles per day upriver. Assuming that they spent about 12 hours on 

the river, then an estimate of the average boat speed would be 2.2 to 2.5 ft/s or 1.5 

to 1.7 mph so that the surface velocity would have ranged from 4.8 to 12.7 ft/s or 

3.3 to 8.7 mph. They continued these surface velocity measurements at different 

locations along the Missouri River, and the table below summarizes these results. 

These were measurements of the surface velocity at different locations along the 

river. They did not have instruments to measure velocities at different depths 

Surface velocity measurements made by Clark 

River reach Velocity 

(miles per hour) (feet per second) 

Mississippi River 

Missouri River between the Osage and Mississippi Rivers 

Missouri River between the Kansas and Osage Rivers 

Missouri River between the Platte and Kansas Rivers 

Platte River 

Missouri River between the Cheyenne and Platte Rivers 

Missouri River above the Cheyenne River 

Columbia River* below the Narrows 

Yellowstone near Clarks Fork of the Yellowstone 

Yellowstone between Clarks Fork and Bighorn Rivers 

Yellowstone between Bighorn and Tongue Rivers 

Yellowstone beween Tongue River and Wolf rapid 

Yellowstone between Wolf rapid and the Missouri River 

4 

5.5 to 6 

6.5 to 7 

5.5 

8 

3.5 

3 

1 to 1.5 

(4.5) 

(3.5) 

(3.0) 

(2.75) 

(2.5) 

5.9 

8.1 to 8.8 

9.5 to 10 

8.1 

12 

5.1 

4 

1.5to2.2 

(6.6) 

(5. 1) 

(4.4) 

(4.0) 

(3 .7) 

*Velocity of the Columbia River is 

given near the Cascade Rapids on 

October 30, 1805, just upstream 

from the tidewater. Velocities 

given inside parentheses were 

indicated in the journals (on 

August 3,1806) as estimates. 

81 
82 

Boils (or kolks) occur 

when fast currents 

propel water and sediment to the surface. 

Modified from Matthes ( 1947) 

Lewis and Clark's Observations and Measurements of Geomorphology and Hydrology, and Changes with Time 

below the water surface (page 80, "River Velocities"), nor did Lewis and Clark 

have instruments specialized to measure turbulent velocities. Nonetheless, Lewis 

observed and described the macroturbulence of the confluence between the Platte 

and Missouri Rivers. One feature of this turbulence is boils (or kolks), and Lewis's 

description seems to fit Matthes's ( 194 7) diagram above of macroturbulence many 

years later . 

... Thirty two miles higher up, and distant 630 [blank] from the confluence of 

the Missouri and Mississippi, the great river Platte disembogues on the S. 

side. The steady, regular, and incessant velocity of this stream, is perhaps 

unequaled by any on eath; notwithstanding it's great rapidity the surface 

of the water continues smooth, except when occasionally interrupted by a 

boiling motion, or ebullition of it's waters. this motion of the water, is also 

common to the Missouri, and Mississippi, below the mouth of that river and 

always takes place in the most rapid part of the current; in this manner the 

This is a downstream view of the White 

River near the confluence with the 

Mississippi River in Arkansas. The boil 

near the bank is dissipating and can be 

identified by its smooth, glassy surface 

surrounded by rough water moving 

outward from the center. 

Photo: john Moody 
Hydrology 

water, is seen to rise suddenly many inches higher than the common surface, 

then breaking with a rappid and roling motion extends itself in a circular 

manner in every direction arround interrrupting the smooth, tho' rappid 

surface of the water for many yards. this ebullition of the water of those 

rivers, is a singular phenomenon, nor do I know to what cause to attribute 

it, unless it be, the irregular 1notion of large masses of sand and mud at 

their bottoms, which are constantly changing their positions ... Fort Mandan 

Miscellany, Moulton, 1987, v. 3, p. 347. 

These observations of Lewis and Clark predate many hydrologic studies in the 

United States. Their stage and velocity measurements are probably the first for 

these rivers. It is unfortunate that the journals were not published until the late 

1800s because these asute observations and simple measurements may have 

spurred others into similar investigation that would have provided us with, perhaps, 50 to 70 years of additional historical data on which to better understand 

the hydrology of western rivers. Desire to control the Mississippi River resulted 

in comprehensive measurements of velocity in the Mississippi River published by 

Humphreys and Abbot (1876). Even so, it was not until John Wesley Powell recognized and promoted the importance of the western water resources beyond the 

100th meridian in the 1870s (Stegner, 1954) that any serious effort was made to 

map and measure the water resources of the Louisiana Purchase. 

83 

IV 

(jeomoryliic and Jfydro{ogic Changes 

in 200 Years 

~E WESTERN expansion of the human population soon followed the 

J, ~~pedition of Lewis and Clark and changed the landscape adjacent to the 

river corridors they traversed. We have Lewis and Clark's written descriptions of 

immence level and fertile plains and meadows, in which, no timber is to be seen 

except on it's own borders and those of it's tributary streams. Now, interstate highways cross and towns spread over the immence level plains, and farms systematically divide the fertile plains and meadows. Agriculture has modified most of the 

semiarid and arid regions drained by the Missouri River. Among the most striking 

features in aerial photographs are the center-pivot irrigation systems that leave the 

characteristic circle of green vegetation on the ground that might otherwise have 

been dry and yellow throughout the summer (below). To produce these irrigated 

fields, the landscape can be leveled by laser-guided earthmoving equipmentdoing in a few days what took erosion and deposition centuries to complete. 

Clark's map ( 1804) of the Big Bend of the Missouri is 

located in what is now central South Dakota. River flow 

is to the east. 

Aerial mosaic (August 1991) of the Big Bend of the Missouri 

River shows the numerous center-pivot irrigation circles 

covering the Big Bend and operated by the Lower Brule 

Indian Tribe. Today's wider river is in the backwater of Lake 

Sharpe reservoir, impounded by Big Bend Dam. 
86 

"View of Pittsburgh" 

painted by Karl 

Bodmer in SeptemberOctober 1832. 

This view taken in 

November 1993 shows 

the Allegheny River 

on the left joining t he 

Monongahela River on 

the right to form the 

Ohio River. 

Lewis and Clark 's Observations and Measurements of Geomorphology and Hydrology, and Changes with Time 

In 1833, Karl Bodmer painted watercolors of the landscape as he traveled up and 

down the Missouri River with Prince Maximilian of Prussia. To fit the immense 

landscapes of the West onto paper, Bodmer often compressed the dimensions of 

the scenes he painted, giving them a slight vertical exaggeration. The details of 

most of his landscape paintings, however, were so accurately rendered that his 

scenes can be relocated today. These paintings provide a visual description of the 

landscape that complements, 30 years later, the written descriptions of Lewis and 

Clark. Some of the scenes that Bodmer painted from the riverboat "Yellow Stone" 

have been located and photographed to provide a visual record of change since the 

expedition of Lewis and Clark. Some landmarks have been significantly changed 

by human activity (below and opposite). Some landmarks have been changed 

because the river has moved several miles from its location in the early 1800s. For 

example, the Missouri River is no longer present to maintain erosion at the base 

of the bluff on which Fort Atkinson was built (page 88, top). Consequently, trees 

have established themselves, and the old riverbed has filled in and been converted 

to farm land and an access road has been built running down from the low spot 

in the bluff. Some landmarks have been changed only by a few homes and planted 

trees (page 88, bottom). In less accessible locations, the landmarks are unchanged 

by humans and appear much as Lewis and Clark observed them (page 89). 
Geomorphic and Hydrologic Changes in 200 Years 

) 

( 

87 

"Blacksnake Hills, Roubidoux's House" painted by 

Karl Bodmer on April 24, 

1833. Joseph Roubidoux 

built a trading post which 

eventually became the 

site of St. Joseph, Missouri. 

This view taken in July 

1992 shows Interstate 29 

along the Missouri River 

with St. Joseph, Missouri, 

in the background. 

" Missouri in the Morning 

below Council Bluffs" 

painted by Karl Bodmer 

on May 3, 1833. The view 

is across the Missouri 

River with the loess bluffs 

on the eastern side of the 

Missouri River. 

This view of Eppley Airfield 

in Omaha, Nebraska, was 

taken October 2002. The 

airfield occupies land 

created when the Missouri 

River changed course. The 

loess bluffs are still on the 

eastern side of the river 

in Iowa. 
88 

"Ruins of Fort Atkinson" 

painted by Karl Bodmer 

on about May 5, 1833. 

This photograph taken in 

June 2002 represents the 

area shown within the 

rectangle on the Bodmer 

painting above. 

"Mouth of the Big Sioux 

River" painted by Karl 

Bodmer on May 8, 1833. 

The view is looking upstream into the mouth of 

the big Sioux River where 

South Dakota, Nebraska, 

and Iowa now meet. 

This same view was taken 

October 2002 on the west 

side of the Missouri River. 

Lewis and Clark's Observations and Measurements of Geomorphology and Hydrology, and Changes with Time 

This site is just east of Fort Calhoun, Nebraska, about I 0 miles north of Omaha. The Missouri 

River is now at least I mile east of the foot of the bluff shown in the painting. The agricultural 

fields in the photograph are now where the river was in 1833. Trees now grow on and cover 

the bluff face, which is about 30 to 40 feet high. The road occupies the low area between the 

bluffs in the painting (upper left corner of the rectangle on the painting). 
Geomorphic and Hyd rologic Changes in 200 Years 

"Bijoux Hills on the Missouri" painted by Karl Bodmer on May 

22, 1833. The view is looking toward the east with the river 

flowing from left to right. 

"View of the Stone Walls" painted by Karl 

Bodmer in August 1833. 

( 

i (rr 

t ~ (' < • Missouri i,l...... J Castle Rock <'?~ l ~ 

I \ -< 

I \.._ i 

/')5 ' f 

"' 

89 

These hills, photographed in October 2002, are known as Twin 

Butte and are the western part of the Bijoux Hills. The Francis 

Case Reservoir is in the foreground and is upstream from the 

Fort Randall Dam in South Dakota. The water level is now 20 to 

30 feet higher than when Bodmer made his painting. The wide 

reservoir is conducive to the generation of waves, which have 

apparently eroded the outcrops of bedrock that appeared at the 

water level in Bodmer's painting. 

This upstream view taken in August 1991 shows the white cliffs 

on the left and Castle Rock to the right. The campsite of Lewis 

and Clark on May 3 I, 1805, is at the mouth of the tributary (Eagle 

Creek or Stonewall Creek) coming in on the right just upstream 

from the point of land jutting into the river. 
90 

This 1920s photograph 

was taken looking east 

at the future site of the 

Bonneville Dam located 

just downstream from the 

Cascade Rapids (Great 

Shute). 

This view was taken after 

the construction of the 

Bonneville Dam. 

Lewis and Clark's Observations and Measurements of Geomorphology and Hydrology, and Changes with Time 

Deschutes R 

0 R 

Long/Short Rapids 

(submerged) 
Geomorphic and Hydrologic Changes in 200 Yea rs 

Karl Bodmer traveled westward only as far as Fort McKenzie on the Missouri 

River near Lorna, Montana, at the mouth of the Marias River and did not paint 

scenes of the Columbia River landscape. However, Arthur Piper, a ground-water 

hydrologist for the U.S. Geological Survey, did photograph landscapes in Oregon 

and Washington and some scenes of the Columbia River during the 1930s, and 

these provide some idea of the area that Lewis and Clark traversed in 1805 and 

1806. Once again, the major change on the Columbia River has been the construction of dams and their associated reservoirs. Cascade Rapids (opposite) and Celilo 

Falls (below) are now permanently under the water backed up by the Bonneville 

Dam and The Dalles Dam, respectively. 

91 

This photograph was 

taken in 1930 of Celilo 

Falls (Great Falls of 

Columbia River) on the 

Columbia River looking 

north. 

This view taken in 1994 

shows the same area of 

Celilo Falls but is now 

covered by the reservoir 

created by The Dalles Dam. 
92 

Elevation, 

in feet 

Lewis and Clark's Observations and Measurements of Geomorphology and Hydrology, and Changes with Time 

Original river profiles 

Present day river profiles. 

(Steps indicate dams 

and reservoirs) 

I Portlanq • • 

Lewiston 

Columbia and 

Snake Rivers 

• Great Falls 

Missouri River 

t 

I 

St. Louis• 

y Great Falls, 

Montana " 3,000 ------- --------\ 

Lewiston, 

Idaho 

' Missouri River 

I ,000 -------..<-----------,------= -­

Portland, 

Oregon 

oY I 

Columbia and Snake Rivers 

3,000 2,000 1,000 

St. Louis, 

Missouri 

y 

0 

Distance from the Mississippi River, in miles 

• Cairo 

Cairo, 

y Illinois 

0 

Pittsburgh, 

Pennsylvania 1000 y 

Ohio River 

0 

1,000 

Since Lewis and Clark traversed the three major rivers-Ohio, Missouri, and 

Columbia-engineering modifications have significantly altered the flow characteristics, the channel cross sections, and the longitudinal profile of the rivers 

(above). Most of these human-induced changes were designed to make the rivers 

easier to navigate, to control floods, to make water available for crop irrigation, 

or to generate electricity. Dams have been the most common means of controlling 

these rivers. 

Navigability of the Ohio River began to be controlled in 1885, when the first of a 

series of wicket dams was completed to maintain a year-round water depth of 6 feet 

in the river near Pittsburgh. By 1929, 52 more wicket dams had been installed to 

regulate the depth of the full length of the Ohio between Pittsburgh, Pennsylvania, 

and Cairo, Illinois. Wicket dams were allowed to lie on the river bottom during 

average-to-high flows and were raised into place only during low flows when they 

were needed to keep the river depths from falling below 6 feet. Beginning in the 

1920s, the wicket dams were systematically replaced by a smaller number of larger 

concrete dams that maintained navigation depths at 9 feet or more. After completion of Olmsted Lock and Dam near Cairo in 2003, 19 of these larger structures 

will control the Ohio River. These concrete dams serve no function in flood control 

(gates are opened wide during high water), but they hold back the waters when 

the Ohio River is low (Johnson, 1991). Comparison of the pre- and post-dam 

discharge hydrographs (opposite) illustrates that the dams have no flood-control 
Geomorphic and Hydrologic Changes in 200 Years 

function because the flood peaks are essentially the same. The differences in the 

hydrographs are more apparent from October through December, when the Ohio 

River flow is kept higher to maintain sufficient navigational depth. 

Engineering of the Missouri River began in earnest during the 1930s when the 

first massive dam was completed on the upper river at Fort Peck, Montana, for 

irrigation and flood control, and the middle and lower reaches were channelized. 

Following World War II, during 1953-63, the construction of five more dams left 

Pre-dam and post-dam 

discharge hydrographs for 

the Ohio, Missouri, and 

Columbia rivers. Note the 

different vertical scales for 

water discharge. 

Discharge, 

in cubic feet 

per second 

Post-dam : 1979- 1998 water years 

-,--,-,--,--,--,--.--.-.--,--.--,-~ 

Oct Nov Dec Jan Feb Mar Apr May June July Aug Sept 

60,000 -----------------------{ 

Post-dam: 

1968-1988 water years 

J 

20,000 -------"' 

' 

~ -"' Pre-d : 1928-1948 water years 

Oct Nov Dec Jan Feb Mar Apr May June July Aug Sept 

600,000 --------------:---;------

Pre-dam: / 

1879-1898 water years-----. 

Post-dam: 

_ 1979-1998 water yea ~ 

2oo.ooo -~"'L:__ ____ _:~~::::-~..--

Oct Nov Dec Jan Feb Mar Apr May June July Aug Sept 

Water year 

Ohio River 

at Louisville, Kentucky 

Missouri River 

at Omaha, Nebraska 

Columbia River 

at The Dalles 

93 
94 

0 

Suspended-sediment discharge, 

in millions of metric tons per year 

Lewis and Clark's Observations and Measurements of Geomorphology and Hydrology, and Changes with Time 

only a few unimpounded miles of Missouri River in the States of North and South 

Dakota. Schlosser (1987) reports that 35 percent of the length of the Missouri 

River is impounded, 32 percent has been channelized, and 33 percent is unchannelized. Because one purpose of the dams on the Missouri River is flood control, 

their effect is rather different from that of the dams on the Ohio River. The two 

seasonal flood peaks are truncated, and a steady flow is released from the dams to 

maintain sufficient depth for navigation of the lower Missouri River from March 

through mid-November (page 68 and 93). 

Hydropower was the principal reason for the series of large dams constructed 

during the 20th century on the reaches of the Snake and Columbia Rivers that 

Lewis and Clark had traversed in 1805-06. These dams also are equipped with 

large navigation locks, capable of lifting barges and their towboats as much as 

100 feet, to permit the shipment of agricultural products and other commodities 

between Lewiston, Idaho, and the Pacific Ocean. Beginning with the Bonneville 

Dam in the late 1930s, eight such structures have converted the former Snake and 

lower Columbia Rivers to a continuous series of slowly moving "lakes." These 

dams, along with the many large and small dams that control the middle and 

upper Columbia in the United States and Canada, have substantially reduced the 

single flood peak of the Columbia River by storing the water and releasing it later 

for power production and navigation (page 68 and 93). 

Although many dams were built for flood control, their reservoirs can be thought 

of as permanent floods that affect the river system upstream from the dam in a 

Sediment discharge 

ca. 1700 

Ohio River 

Gulf of Mexico 

1980-1990 

Gulf of Mexico 

Construction of reservoirs 

caused a large reduction of 

sediment in the Missouri 

River between I 700 and 

1990. In contrast, sediment 

loads in the Ohio River have 

increased as results of deforestation and rowcrop farming. 

(Meade, 1995) 
Geomorphic and Hydrologic Changes in 200 Years 

area, in hectares 

. 0- 15 

-- • 15 - 50 

• 50-90 

• 90-150 

e I SO-l 52,167 

Location of small dams 

and reservoirs in the 

Missouri River Basin. 

Most dams were built 

after 1900 with fewer 

being built during the 

war years and a decrease 

in building in the 1970s, 

1980s and 1990s. 

95 

Provided by David Mixon and Deborah Martin 

quite different way than the annual floods, which lasted for only a few weeks or 

perhaps a month. Reservoirs now cover many of the meanders, riffles, rapids, and 

falls encountered by Lewis and Clark. Dams trap sediment in the upper reaches 

of reservoirs where tributaries enter the relatively quiet water of the reservoir 

and deposit sediment to create deltas and wetlands, which can have effects on 

the environment that are both positive and negative. Dams also affect the river 

system downstream (Williams and Wolman, 1984; Collier and others, 1996). The 

closure of the downstream-most dam at Yankton, South Dakota, in 1953 caused 

extensive changes in the sediment transport and other characteristics of the flow 

of the Missouri and Mississippi Rivers that could be observed all the way to the 

Gulf of Mexico. The suspended-sediment load of the lower Missouri River during 
96 Lewis and Clark's Observations and Measurements of Geomorphology and Hydrology, and Changes with Time 

the time of the Lewis and Clark expedition is estimated to have been about 320 

million tons per year. Today, 200 years after Lewis and Clark, the lower part 

of the muddy Missouri transports only about 86 million tons per year (Meade, 

1995). This is not enough to replenish the marshes and islands at the mouth of 

the Mississippi River. 

The dams that trap sediment are not all large. Many smaller dams almost cover 

the landscape in some areas, and their combined effect may rival that of the large 

dams (page 95). Each dam traps sediment and organic material and regulates the 

hydrologic regime downstream. Sediment that was once thrown out by tributaries 

has been reduced, and a river full of Sand bars and riffles has largely disappeared 

in many places. 

While the Missouri River did not carry the most water, it was perhaps the most 

dynamic river traversed by Lewis and Clark. Most of the Missouri's length, greater 

than that of either the Ohio or Snake-lower Columbia River reaches traversed by the 

Corps of Discovery, was not confined in narrow canyons or valleys and was truly an 

alluvial river forming and reforming its own channel and flood plain. Subsequent 

channelization for purposes of navigation has caused many of the changes in the 

Missouri River. Using Clark's river distances as the basis for comparison, channelization has probably shortened the Missouri River by about 21 percent during the 

last 200 years. Nearly all of this shortening of the river was in the lower one-third 

below the Gavins Point Dam in South Dakota. Meander bends were artificially cut 

off, and wing dikes were built to channelize the flow. Pile dikes were built to trap 

sediment, bank revetment was installed to stabilize the banks, and levees were built 

to keep floodwaters off the flood plains. These engineering activities, designed to 

improve commerce and support agriculture, have resulted in narrower channels but 

wider flood plains as the great number of islands have been connected to the bank 

by the deposition of sediment between the pile dikes (photos on opposite page). 

Channelization has eliminated those shallow braided reaches of the Missouri where 

Lewis and Clark were at a great loss to find the Channel of the river. 

It is notable that Lewis and Clark never commented on overbank flooding during 

their trip up the Missouri River, which according to hydrographs on page 68 was 

made near the crest of the annual snowmelt flood. This may illustrate the consequence of channelization and confining a formerly wide river to a narrow channel. 

The river must now rise much higher vertically to overflow its banks, while previously it could spread out over wide areas of islands and flood plain at a relatively 

shallow depth. 

Vegetation has encroached on and grown into many rivers of the west as a consequence of projects designed to control rivers. The annual floods and ice-jam floods 

in the spring and dry river channels in the late summer, observed by Lewis and 

Clark, were natural ways to keep some channels free of vegetation. Now dams 

decrease the magnitude of floods and provide water in the summer. The encroach-
Geomorphic and Hydrologic Changes in 200 Yea rs 

Engineering projects have 

eliminated most of the braided 

reaches of the Missouri River. 

This series of photographs was 

taken at Indian Cave Bend Point 

on the Missouri River near mile 

5 17 about 18 miles upstream 

from Rulo, Nebraska. The view 

is downstream, from Nebraska 

(near bank) into Missouri (far 

bank). The 1934 photograph 

was taken before the construction of wing dams. 

Photographs provided by Norm Stucky 

ment of vegetation into the channel also traps and stores sediment, changing the 

geomorphic configuration of the river (Friedman and others, 1998). The combined 

effects of damming, channelization, and vegetation encroachment has changed 

the character of the Missouri River relative to when Lewis and Clark struggled 

upstream. It has caused the water-surface area of the Missouri River to decrease by 

49 percent, the channel area to decrease by 41 percent, and the number of those 

formidable sandbars and unconnected islands to decrease by 99 percent (Funk and 

Robinson, 1974; Hallberg and others, 1979). 

97 

September 1934 

September 1935 

March 1977 
98 Lewis and Clark's Observations and Measurements of Geomorphology and Hydrology, and Changes with Time 

Missouri River channel changes 

1890 

Braided 

Islands ~ ? 

1976 

Channelized 

An 1890 map shows a braided reach 

of the Missouri River near Nebraska 

City, Nebraska. The river is flowing 

from north to south, and the islands 

are shown in brown. Some islands are 

connected to the main flood plain. 

Weeping Water Cr. 

\ A 1976 map shows the same reach of 

the Missouri River. The river is not 

braided but channelized, and no islands 

exist as of 1976. 

From Hallberg and others, 1979 

0 2 4 Miles 

Nebraska City ' r--.. ~ ..;. 

Nebraska % Iowa 

/->L ~wer \ ':.. ~ 

que ~ ~ AP AREA '-,, f''"",.-. __ , ( · c . o,/' . 

'. e..,.. ·*' · 

Missouri :?: 

Ka nsas 

/ 

The change in channel-surface area is relatively easy to determine from maps 

and aerial photographs. However, the thickness of sediment on the flood plains 

is not as easy to determine. This stored sediment also contains large amounts of 

stored carbon, which is of current concern to many research scientists interested 

in the global carbon budget (Stallard, 1998). Some idea of the thickness can be 

seen in the photograph series on the opposite page, but the thickness probably 

varies from inches to many feet. Two examples of perhaps the upper limit for 

thickness were determined when two steamboat wrecks were excavated out of the 
Geomorphic and Hydrologic Changes in 200 Years 

Steamboat Arabia fou nd in 1987 

north of Kansas City, Missouri, 

was buried under about 45 feet 

of flood-plain sediment. The 

paddle wheel is 28 feet tall. 

Photo: Arabia Steamboat Museum, Kansas City. Missouri 

flood plain. One, the Arabia, which sank in 1856, was found buried in a cornfield 

near Kansas City, Missouri, covered by as much as 45 feet of sediment. Another, 

the Bertrand, which hit a large snag and sank in 1865, was found a century later 

buried under about 30 feet of sediment north of Omaha, Nebraska. 

The changes on the Ohio, Missouri, and Columbia Rivers illustrate similar changes 

on other rivers in the United States. Very few, if any, rivers have escaped the human 

desire to control nature. Today's Missouri River is not the dynamic river observed 

by Lewis and Clark that annually built and recycled its flood plains. However, 

there has been a growing interest in river restoration in the United States. Because 

so few natural rivers remain, the observations of Lewis and Clark provide some 

insight into the character and processes of natural rivers that may help guide river 

restoration efforts. This is especially true for the Missouri River, which for the 

most part was an alluvial river, unconfined, and forming its own channel and 

flood plain. Besides making direct observations of the river itself, Lewis and 

Steamboat Bertrand found north of 

Omaha, Nebraska, was buried under 

about 30 feet of flood-plain sediment. 

Photo: john Fu~on, National Geographic Society 

99 
100 Lewis and Clark's Observa tions and Measurements of Geomorphology and Hydrology, and Changes with Time 

Clark recognized the interconnections between the river and the vegetation and 

animals that lived on or next to it. Beaver, for example, whose importance Lewis 

and Clark observed as being very instrumental in the morphology of the Missouri 

River, is recognized today 200 years later, as a keystone species (Outwater, 1996) 

that affects other species by engineering rivers and creating wetlands. The legacy 

of the keen observations in all scientific fields left by Lewis and Clark needs to be 

continued today, and into the future, to discover the complex but important interconnected relationships in riverine ecosystems. 
(j{ossary and 5\hhreviations 

azimuth horizontal angular distance from a fixed reference direction, which 

commonly is north 

bearing horizonal angle measured from north toward a landmark 

chain 100 metal links, each link is 7.92 inches such that 1 chain equals 66 feet 

eolian pertains to wind 

fluvial pertains to river and streams 

E. East 

grs. grains (1 grain equals 0.065 gram or 0.002285 ounce) 

Gs. gallons 

I inch or inches 

lb pound 

league equals 3 miles 

L.S. lard., larboard, port, or the left-hand side of a vessel 

median middle value, 50 percent of the values are less than this value and 

50 percent are greater than this value 

mes. miles 

mph miles per hour 

ms. miles 

N. north 

Opsd. opposite 

po. pole 

pr. per 

pt. point 

R. nver 

S. south 

thro' through 

S.S. or Stard. starboard or the right-hand side of a vessel 

yd. yard 

yds. yards 

transport movement of soil or sediment by air or water in a specified time 

tho. though 

W. west 

&c et cetera, and so forth 

" seconds 

101 
102 

'Rivers, Creeks, and Sites 5\{o, 

Big Muddy 

Fort Peck' I -Little Muddy 

-WhiteEart 

Poplar Judith (Porcupine) North 

Garriso 

GATES OF THE ROCKIES ~ M o n t a n a Canyon Ferry ~ ~e ..... '1: 

Jefferson M,._ssq, YelloVl" 

THREE FORKS 

knife - .Fort 

<Y. Bismarck 

eqft • 

Cq'Znot-'o all -

Moreau ~ s 0 u t h 

-& foe ere p, Cbe')'et' ~... Oahe, 

CK che Pierr~ 

ILLS White Big 

I 

I 

NEBRASKA SAND: 

l:Jebraska I 

I 

I 

I 

I 

I 

I 

I 

I 

I 

I 

I 

I 

I 

c 

'6 "' 

·c 

... 

E 

.c 

c5 

0 

-BOUNDARY OFTH 

LOUISIANA PURC ASE 

ex i co 

I 

I 

I 

I 

I 

I 

I 

I 

I 

:re 
e Lewis and C{ark Corridor 

a 

This map shows the hydrologic, geomorphic 

and cultural features mentioned in the text. Also 

shown are the many dams which now cross the 

rivers traversed by Lewis and Clark. 

Minnesota 

Wisconsin 

Michigan 

-Little Sioux 

Ka1ls4s 

Kansas City 

s a s 

ahoma 

Iowa 

·1:2 .~ 

~ 

-Platte Grand I I I i n o i s 

Joseph / 

Ropewalk 

Camp. 

Waverly \ 

Lamine 

Osage "b-q, 

0~ \l 

u~" M i s s o u r i 

OZARK-OUACHITA 

HIGHLANDS 

Arkansas 

Louisiana 

103 

G e o rg i a 

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