Charles-Alexandre Lesueur in Missouri: 1826 (Monograph 20)

A Geological Summary of the Journal of the Voyage of Charles-Alexandre Lesueur from Harmony, Indiana to Southern Missouri in 1826

Author: Walter A. Schroeder, June 2003

1826 Voyage of Charles-Alexandre Lesueur in Missouri: Map and Profile of Wilkinson’s Cave at Mine Lamotte, Missouri state, 1826. Le Havre (France), Muséum d’histoire naturelle. Via Whitney Walton

Geology article to accompany Journal de voyage de Charles-Alexandre Lesueur depuis New Hairmony (Indiana) jusqu’au sud du Missouri en 1826 (Documents du Museum d’histoire naturelle du Havre no. 42 100 a 42 137)

Tip: Click here to open a modern geological map to better follow this narrative.

Click Image to Open

Introduction to the 1826 Voyage of Charles-Alexandre Lesueur in Missouri

The area traversed by Lesueur on his trip to Missouri in 1826 included the geologic extremes of the Mississippi Embayment, a deep structural basin still experiencing major earthquakes, and the Ozark structural dome where some of the oldest rocks of the United States are exposed. The Ozark dome, the goal of Lesueur’s journey, is one of the richest metalliferous regions of the United States.


The Ozark dome is centered in St. Francois and Iron Counties, Missouri. In Precambrian time, 1.5-1.9 billion years ago, a complex structure was created consisting of granite batholiths and rhyolite, syenite, and other volcanic intrusives and extrusives. A mountainous topography developed on this structure. Paleozoic seas then covered this igneous mass and left a basal formation of sandstone followed by thick sequences of limestones, dolomites, and sandstones. Toward the close of the Paleozoic Era, uplift created the Ozark dome.

The Ozark Dome is Exposed

Since then, for approximately 300 million years, the Ozark region has been above sea level and the thick sedimentary cover has been continuously eroded. Removal of the sedimentary cover has gone far enough at the center of the uplift to expose the igneous complex over an area of five thousand square miles. The dome center is now an exhumed, mountainous landscape of smoothly rounded igneous summits, called knobs, intermixed with limestone- and sandstone floored basins, where the sedimentary cover has not yet been removed. This region of Precambrian igneous rocks is called the St. Francois Mountains.

The Iron Mountain, St. Francois County, Missouri Territory
West of Ste. Genevieve

Surrounding it is a deeply dissected plateau on the gently dipping limestones, dolomites, and sandstones. The stratigraphic dip is generally so slight that at any single bedrock exposure, as along a stream bank, the formations appear to be horizontally bedded. However, where where the stratigraphic dip is sufficient, as west of Ste. Genevieve, a cuestaform topography has developed. The deeply dissected plateau consists of a monotonous maze of narrow valleys and narrow ridges lacking linearity. Numerous streams drain the dissected plateau radially outward from its center. They are swift, gravel-bottomed, with hardly any alluvial plains along them.

River Bluffs

The various geologic formations are geometrically arranged by decreasing age in encircling belts from the structural center of dome outward. Early Cambrian sandstones comprise the first belt and many of the interknob basins. They are followed by later Cambrian limestones/ shales, and dolomites, which are in turn followed by a thick sequence of Ordovician dolomites and sandstones. Silurian, Devonian, and Carboniferous (Mississippian) limestones and dolomites, the outermost belt in southeastern Missouri, outcrop in the bluffs along both sides of the Mississippi River in Missouri and southern Illinois.

Encountering the Oldest Mountains in North America

Therefore, as Lesueur traveled from New Harmony, Indiana, to the mineral region of Missouri, he encountered progressively older formations. He would have noted an impoverishment of the record of life in the rocks as he moved from paleontologically rich Carboniferous formations to paleontologically poor early Cambrian and then finally into Precambrian igneous rocks devoid of life forms.

1826 Voyage of Charles-Alexandre Lesueur in Missouri

Lithology and Minerals

The Precambrian igneous rocks at the center of the dome structure are a complex of extrusives and intrusives. The oldest rocks are extrusive, pink to purplish-red rhyolites. (Lesueur identifies syenite, 42 137 recto). They were intruded by gray, pink, and red granites, formed from deep-seated magma that had cooled at depth as a batholith. (Lesueur noted granite, 42 136 recto). Molten magma then intruded into these masses forming dikes and sills formed of gabbro and diabase. Iron in the form of magnetite is the chief mineral resource of these igneous rocks. Iron mining began in 1815. Lesueur noted the Springfield iron furnace between Caledonia and Potosi and Iron Mountain (41 137-3 recto; dessin 42 094). Surface iron mining has since been replaced by deep mines into the same magnetite-rich Precambrian rock. At times Missouri has ranked third in the United States in iron production.

The Source of the Pb (lead)

The Cambrian formations that form the first belt around the Precambrian core are composed of sandstone detritus from erosion of the igneous rocks and, more importantly, carbonate rocks that have been permeated with metal-bearing solutions derived from decay of the igneous rocks. These formations, especially the Bonne Terre limestone and dolomite, are the chief source of lead in the region. Lead mining began at Mine la Motte about 1720. Before the mid-nineteenth century, lead ore was mined by digging surface pits up to twenty feet deep. Chunks of pure galena up to ten pounds could readily be picked up from the surface. Because lead ore occurred on the surface over hundreds of square miles, virtually anyone with a pick and shovel could become a miner.

Mining the Lead

Wealthier persons used black slaves for miners and smelteries, and others dug for themselves. Lesueur describes lead mining (42 134 through 42 137) and depicts it in his sketches (dessins xx xxx through xx xxx) . Although shaft mining was introduced as early at 1799, it did not become common until mid-nineteenth century. When Lesueur visited, lead smelting was still by crude log furnaces. The slag that was left over from the crude smelting contained as much lead as that which was recovered (42 135 recto [Slague ou rebut] contient plus de ploirb que celui qua I’on a obtenu.)

1826 Voyage of Charles-Alexandre Lesueur in Missouri

The World’s Largest Lead-Mining District

By the end of the nineteenth century the region had become the world’s largest lead-mining district. After two and a half centuries of exploitation, the lead was exhausted by 1972, and lead-mining moved forty miles to the west, on the other side of the exposed igneous dome, where deep mines (up to 1,500 feet) bring to the surface lead ore from the same formations and keep Missouri near the top of lead-producing regions of the world.

Rich in Other Valuable Minerals

During the process of lead mining and smelting, zinc, silver, copper, manganese, nickel, and cobalt are also recovered from the same ore. Lesueur and others noted the presence of some of these metals (Lesueur’ s later publication, footnote 34), but they could not be recovered until later technological advances made it possible. Barium sulfate, or barite, also vein-permeates the Cambrian limestones and dolomites. The barite was subsequently weathered out into barite-rich red clay that occurs over hundreds of square miles. Lesueur noted its presence near Burton (Potosi) (42 137-2 verso). (See the Geology of the Potosi and Edgehill Quadrangles (1930) –  By C. L. Dake)

Le tuf blanc

The French- speaking local population called it tuf blanc, or tiff. At first it was discarded as waste during lead mining, but it became valuable in the late nineteenth century with the rise of the petroleum industry. French Creole families (piocheurs) dug it from shallow pits until mechanization was introduced in the twentieth century. In the first half of the twentieth century the Potosi-Old Mines region of Washington County was the world’s largest barite producer, but production has greatly dwindled since then.

Chert is Observed

Later Paleozoic formations do not contain metal resources of importance. The Ordovician formations are composed of hundreds of feet of limestones (calcium carbonate), dolomites (magnesium carbonate), and sandstones, with dolomites greatly dominating. Lesueur did not differentiate between limestones and dolomites. In fact, they are difficult to distinguish by observation and were not generally recognized until the twentieth century. Both dolomite and limestone formations are extremely rich in chert (including flint and jasper).

It Gave the Appearance of Snow

As the calcium carbonate and magnesium carbonate is dissolved and carried away, the insoluble chert remains on the surface and creates a surface armored with chert fragments. Some soils naturally contain as much as 60 percent chert fragments. Lesueur was impressed by the abundance of chert as he walked northwestward from Jackson (42 132 verso: marchant toujours sue le silex). In the distance, he said, the white fragments on the surface gave the appearance of snow (42 132 verso: collines de ce sileXf lesquelles avaient de loin I’aspect d’etre couvertes d’une legere couche de neige).

Devilishly Sharp Rocks

He noted that the sharp edges of chert ruined his shoes (42 133 recto: les silex avaient acheve de ruiner mes souliers). He noted that the hard chert was fashioned into arrowheads (42 107 recto: forme en tete de fleche par les Indiens). He further noted that the carbonate rocks were usually red-stained from iron oxides on the surfaces (42 106 recto, 42 107 recto).

Abundant Karst Landscapes

As carbonate rocks, both limestones and dolomites are soluble. The extremely long, continuous period of subaerial erosion since the close of the Paleozoic Era has permitted huge underground voids to be created. The Ordovician formations are associated with extensive karst landscapes. Though Lesueur did not pass by any major cave, he noted a natural bridge (42 127 recto and dessins 42 034 en bas and 42 035), streams that disappeared underground (42 124 verso: ravins dont plusieurs se perdent sous terre), and several sinkholes (42 124 recto: plusieurs trous infundihuliformes). (More about Missouri’s Karst Topography)

St. Peter Sandstone into Glass

One of the Ordovician sandstones, the St. Peter sandstone, is especially noteworthy. As remarkably pure silica, it is bright white when exposed on bluffs. Lesueur noted its purity and suggested its use for glass-making (42 115 verso: le gres . . . pour rait etre employe pour le verre). Indeed the St. Peter sandstone became the basis for a major glass-making industry at Crystal City on the Mississippi River south of St. Louis. Southern Illinois and adjacent portions of Kentucky and Indiana are underlain by Carboniferous formations that dip generally northward. As Lesueur traveled down the Ohio River to the mouth of the Cumberland River at Smithland, Kentucky, he saw progressively older strata of limestones and sandstones with occasional coal beds.

1826 Voyage of Charles-Alexandre Lesueur in Missouri

Fluvial Geomorphology

Nowhere that Lesueur traveled on this trip had the land been glaciated. However, he was very close to the southern limit of Pleistocene glaciation, which lies along the Mississippi River from St. Louis to southern Illinois, then across southern Illinois to the Wabash River and into southern Indiana, just north of New Harmony. Nevertheless, the region that Lesueur traversed was greatly influenced by Pleistocene events. Both the Ohio and Mississippi Rivers were major drainageways for meltwater from glaciers and from the emerging Great Lakes. Thus the two rivers carried enormous volumes of water as recently as 10,000 years ago and at times occupied different courses than today.

Leaving La Trinité for Commerce, Missouri

The Pleistocene Ohio River once occupied a valley north of Cairo (La Trinité), Illinois. Lesueur traversed this abandoned glacial drainageway when leaving La Trinité for Commerce, Missouri (42 022: le terrain est tout d’alluvions et de depots recents). As a result of changing locations during the late Pleistocene, the present Ohio River at places flows in a broad valley and at other places in a valley constricted by bedrock walls. Lesueur noted this changing nature of the Ohio River valley (dessin 42 015: le terrain des deux cotes devint assez eleve).

The Ozark Escarpment

The Pleistocene Mississippi River formerly turned west at Cape Girardeau and flowed at the base of the Ozark Escarpment for over 200 miles before joining the ancestral Ohio River in the state of Arkansas. Less than 10,000 years ago, the Mississippi River took a new course through a 6-mile-long spur of the Ozark highlands above Commerce. (Read another Monograph about this area) Lesueur crossed the abandoned Pleistocene course of the Mississippi River as he walked the 6 miles from La Grand Chaine (Cap La Cruz) to Cape Girardeau and noted stagnant water, enormous trees and numerous waterfowl (42 116 recto and verso: les eaux mortes sans courante; Nous entre Mmes sur un fond de terreau tres rich de depots du Mississippi.).

1826 Voyage of Charles-Alexandre Lesueur in Missouri

Draining Over One Million Square Miles

Both the Ohio and Mississippi Rivers experience major floods on the average of once every few years and minor floods virtually every year. The latter river, especially, experiences enormous annual ranges in discharge because it drains over one million square miles, much of which lies in the subhumid American Great Plains where rainfall is concentrated in spring and early summer. Floods usually occur in May-June; low flows in December-January. Lesueur visited the region in April-May. Lesueur commented several times on alluvial features due to flooding (42 101 verso). He rightly attributed ponds and marshes to water left from flooding (42 107 recto; 42 109 verso), although he did not note that their presence was associated with ”fevers” (malaria) and was responsible for settlers avoiding wet flood plains.

A Rowdy River System

He recognized both natural levees created by river water spilling out of the channel and associated backswamps away from the river (42 147 recto: Le bord de la river etant plus eleve . . . il en results que [sur] le derriere de la ville^ il y a une petite lagune d’eau) Even when not flooding, these two large rivers are active alluvial environments with frequent bank cavings and channel shifts and islands that grow and disappear annually (42 105 verso: un banc de sable). The two rivers are so swift (6-8 miles per hour average) that boats could not safely tie up along their banks, and the quiet-water mouths of small tributaries were used for harborage (42 109 recto: Une petite crick . . . forme une espece d’abri pour les bateaux).

Mississippi Embayment and Earthquakes

The Ozark structural dome is abruptly truncated on its southeast side by the Mississippi Embayment, a deep structural basin. The boundary between the two structures, called the Ozark Escarpment, is a sharp, straight line variously interpreted as a fault scarp or an erosional escarpment or a combination of the two. The head of the basin is at Commerce and La Trinité and extends southward all the way to the Gulf of Mexico. The basin began subsiding during Paleozoic time and continued to receive marine sediments into Cretaceous and Tertiary time. Later, fluvial erosion removed some of the basin fill.

Sediments Several Thousand Feet Thick

More recently, during Cenozoic and Pleistocene time, the basin received terrestrial sediments several thousand feet thick. The northern end of the Mississippi Embayment, around the confluence of the Ohio and Mississippi Rivers, is an active seismic region called the New Madrid Seismic Zone. Approximately 150 earthquakes with a magnitude greater than 1.0 (Richter scale) occur each year. In the winter of 1811- 1812, fifteen years before Lesueur visited the region, three severe earthquakes occurred near New Madrid, Missouri, that have been measured at 8.6, 8.4, and 8.7 (Richter scale).

1826 Voyage of Charles-Alexandre Lesueur in Missouri

The New Madrid Earthquakes

They are thought to be the largest earthquakes experienced in the continental United States in historic times. Major alluvial tracts sunk and others rose, and the course of the Mississippi River was affected. The earthquakes caused the depopulation of some frontier communities and retarded the growth of others. Lesueur certainly knew about these powerful earthquakes, but in the journal of his Missouri trip he noted only that subterranean shakings (42 107 recto: ebranlements sou terrains) could have caused the uneven terrain he observed.

(Note to editor: Does Lesueur have anything to say about the famous earthquakes in his journal for his journey past New Madrid on the lower Mississippi River? If so, reference to those comments should be noted here.)

Walter A. Schroeder’s Map: Lesueur’s Travel to Missouri 1826

Legend for Walter A. Schroeder’s Map: Lesueur’s Travel to Missouri 1826 (above)

  • T – Tertiary
  • K – Cretaceous
  • C – Carboniferous
  • SD – Silurian and Devonian
  • O – Ordovician
  • C – Cambrian
  • PC – Precambrian

(all town abbreviations are encircled)

  • NH – New Harmony
  • S – Smithland
  • LT – La Trinité (Cairo)
  • C – Commerce (town)
  • CG – Cape Girardeau        
  • J – Jackson
  • MLMMine la Motte
  • IM – Iron Mountain
  • P – Potosi (Burton)
  • SL – St. Louis
  • SG – Ste. Genevieve
  • NM – New Madrid
Other Map Line Work
  • …………… Pleistocene course of the Mississippi River
  • <=== Pleistocene course of the Ohio River
  • __ __ __ Limit of Pleistocene glaciation
  • _ _ _ _ _ Boundaries between different geologic ages of rocks
  • _ . _ . _ State boundaries
  • _______ Boundary of the Mississippi Embayment

Walter A. Schroeder‘s other writings (Book1, Book2, WorldCat Listing)

1826 Voyage of Charles-Alexandre Lesueur in Missouri

Missouri Geological Survey: Maps of Missouri Geology

Charles-Alexandre Lesueur
The collection of Charles-Alexandre Lesueur at muséum d’histoire naturelle du Havre

Voyage en ex-Louisiane française 1826: Charles-Alexandre Lesueur aux Etats-Unis d’Amérique

Paperback – May 1, 2004 – French Edition by Maryvonne Nedeljkovic (Author)

“Lorsque Charles-Alexandre LESUEUR débarqua en mai 1816 à New York, il ne se doutait pas qu’il allait être le témoin, entre 1816 et 1837, des nouvelles répartitions territoriales de l’ex-Louisiane française ainsi que de la création de nouveaux Etats et de leurs efforts de fédération politique.. Dans le journal correspondant à l’année 1826, LESUEUR décrit les étapes d’une mission scientifique partie de New Harmony et comprenant le Dr. TROOST, géologue, M.CULLOCK, minéralogiste et lui-même, dessinateur naturaliste. Du 26 février au 28 mars 1826 ces trois scientifiques firent des observations de terrain, décrivirent les exploitations existantes et explorèrent les ressources minières et minérales potentielles des Etats qu’ils allaient traverser : l’Indiana, l’Illinois, le Tennessee, le Missouri. Le Journal de Voyage de Lesueur dans l’ex-Louisiane française, et en particulier dans le Missouri, est un ensemble d’observations et de réflexions riche d’enseignements…”

In the Field with Charles-Alexandre Lesueur (1778-1846): Science and Community on Three Continents

Whitney Walton – Purdue University Volume 46, 2018 – Permalink:

Initially, the hope for fieldwork opportunities seemed well founded because just weeks after the group arrived in New Harmony, on February 26, 1826, Lesueur and Troost started an expedition to lead mines in Missouri. Lesueur’s visual and textual journals of the trip, like the accounts of the Baudin Expedition, reveal the challenges of doing fieldwork in the wilderness, and the men’s observations of and adaptations to local culture. Traveling overland as well as by boat along the Ohio and Mississippi Rivers to reach Missouri, Lesueur, Troost, and a doctor Cullock encountered backwoodsmen, settlers, and slaves.[49] After being dropped off in the dark on a tiny point of land from which they risked falling into the river and being carried off by the current, the three men formed a human chain to ascend the river bank…

Lesueur’s Lampreys of 1826: The Quest to Find Wilkinson Cave and Evidence of American Rook Lamprey in the St. Francis River, Missouri

Robert A. Hrabik – Oak Ridge, Missouri – Summer 2021 American Currents

“After explaining who I was and the purpose of the intrusion, I asked about caves in the area and her response floored me “Yes, there are caves on my property along the St. Francis River upstream of the confluence with Cedar Bottom Creek.” Ms. Rucker went on to explain that while she lived in Fredericktown, she often spent evenings and weekends at the farm where her father raised cattle. As a little girl, she used to climb the bluffs along Cedar Bottom Creek and the St. Francis River and play near the caves (she wouldn’t go in the caves, too spooky, she said). Since these caves are situated high above the St. Francis River on her property, thus it seemed very unlikely that the river would have ever flowed into the caves during Lesueur’s time.”

Useful Knowledge” in Charles Alexandre Lesueur’s Visual and Textual Accounts of Missouri in 1826 (pdf)

Whitney Walton – – DOI: 10.5206/mfdsecfw.v6i1.14082 – Volume 6, Issue-numéro 1 2021 – Pédagogies et héritages • Pedagogies and Legacies – Dir. Servanne Woodward

“Lesueur fulfilled art historian Barbara Stafford’s characterization of eighteenth-century scientific travel that included art as an objective record of fact, serving “a practical purpose” as a “vehicle for knowledge .” Starting with Daniela Bleichmar’s concept of “visual epistemology: a way of knowing based on visuality, encompassing both observation and representation,” this essay claims that Lesueur’s art and scientific practice adhered closely to a belief in the authority of art from direct observation in nature, and they served different professional, educational, community, and potentially commercial purposes. It charts the conditions under which he produced the art, the purposes(s) of the art, the types of art (sketches, paintings, prints, landscape drawings), and the intended audience through four types of subjects from the expedition to Missouri in 1826: the challenges of scientific fieldwork, Blacks in Missouri, lead mining, and inland but especially riverside towns…”

Would you like to read more Monographs?

If you have any suggestions, comments, or critiques please email

Related Pages:

Leave a Reply