Missouri River, South Dakota's Great Divide

"What does the Missouri mean to you?" I was asked.

South Dakota is one of those roughly rectangular states in the heartland of the USA. The Missouri River runs through it north to south, dividing it into two nearly equal but very different halves. To the west landscapes are mostly rugged and sparsely vegetated. To the east they're subdued and covered in plants. So after pondering the sign's question, I decided that was what the Missouri meant to me—South Dakota's Great Divide.

Modified from this map; original source not given.

The difference can be seen even from afar: brown west of the river, green to the east (Google Earth, modified).

The contrast west and east of the Missouri has long intrigued those travelers who pay attention. In 1839 Joseph Nicollet, surveyor with the US Corps of Topographic Engineers, led an expedition up the river as far as Fort Pierre, and then northeast by land. They experienced a dramatic change in landscape almost immediately. The "Great American Desert" west of the river was gone. Instead ...

"... the vast spaces opening to your gaze, the astonishingly richer vegetation, the smoother undulations breaking the monotony, the purity of the water in the streams and rivers flowing into the Missouri, the nature of the woods shading them—everything proclaims a favorable change in the physical aspects of the country." (Nicollet 1843)

Why the sudden change? It can't be moisture. Precipitation does increase going east but only gradually. And there's no significant change in elevation, nothing to disrupt South Dakota's gentle downward slope from the Rocky Mountains eastward. But there is a huge difference in substrate, as Nicollet noted:

[Land east of the river] "is covered by a species of deposite of the kind for a long time known by the name of diluvium; but as this word implies a theoretic idea as regards the accumulation of such deposites, the cause of which is still open to controversy, it is now very generally abandoned, and the designation of erratic deposites, among others, adopted in its stead. I have, therefore, used the latter expression, as comprehending a vast deposite of sand, gravel, pebbles, and clays, ... and masses of rocks transported to a distance from their original position, usually called erratic blocks."

Nicollet's "vast deposite" east of the Missouri is fine ground-up material rich in plant nutrients, with "erratic blocks". Farmers call it "boulder clay". Photo courtesy Dave Rintoul.

In the above description, Nicollet alluded to a controversy surrounding these deposits. In fact, it was a raging debate. Similar material in Europe had long been attributed to the Biblical Flood, but some geologists were pushing a radical new idea—glaciers! After all, these kinds of deposits were associated with modern-day glaciers in the Alps. Even so, most geologists considered the "glacial theory" complete nonsense. Ice sheets at lower elevations in Europe? or on the plains east of the Missouri River? Ridiculous! Nearly three decades would pass before climate change, ice ages and continental glaciers were widely accepted (1).

The Missouri is the west boundary of land once glaciated. But why? (modified from Johnson & Knight 2022).

It's very hard to imagine massive sheets of ice covering eastern South Dakota, especially on a torrid summer day. But they did, and multiple times. Starting about 2.6 million years ago, glaciers advanced south from the Arctic six or seven times, sometimes reaching as far as Kansas and Missouri. Advances alternated with interglacial periods, when the ice melted back. In South Dakota the last ice melted just 11,000 years ago (Gries 1996; Johnson & Knight 2022).

As it flows, a glacier grinds and planes the land and carries off the fragments in its base, making it even more abrasive. When it melts, it leaves behind thick deposits of ground-up material—Nicollet's "erratic deposites", now called ground moraine. After multiple advances and melting during interglacials, eastern South Dakota was covered in ground moraine—the source of the fertile soils east of the Missouri River.

Nicollet's "astonishingly richer vegetation" east of the Missouri River was mostly tall grass prairie. But now it's largely gone, replaced with crops.

Some readers may be wondering, as I did: Why are there glacial deposits east of the Missouri but not to the west? Did the river block the ice? That explanation is tempting, but there's a better one. Look at the map below for clues.

Major streams of South Dakota; modified from Gries 1996.

In the late 1850s and again in the late 1860s (before and after the Civil War), Gouverneur K. Warren of the US Army Corps of Engineers studied the Missouri River and its tributaries. In his 1869 report he described the extensive glacial deposits ("drift") and explained why they stopped at the Missouri, why there were none farther west.

"I have determined the south western limit of the glacial drift action to be the Missouri river ... From the Missouri river to the Rocky mountains, over a space varying from 300 to 500 miles in width, no drift is found ... There, then, on that limit a river must have been formed to carry away the melting water from the glacier, and this limit was the Missouri river, and that was the river formed thereby. It cut along this glacial limit because all the streams west of it came from the mountains toward it, down the inclined plain, and there their old course was terminated" [italics mine].

Many years later, USGS geologist Richard Foster Flint agreed with Warren. "The belief, advanced as early as 1869, that an ice sheet flowing southwestward blocked these valleys and detoured the drainage so as to form the Missouri River is confirmed." As evidence, Flint described three anomalous features of the Missouri (two can be seen in the map above). First, it doesn't follow the gradual decrease in elevation west to the east. In fact it flows mostly south, perpendicular to regional slope. Second, its valley generally is steeper-walled than those of its tributaries, indicating youthfulness. Finally, distribution of its tributaries is very lopsided—all major streams enter from the west (Flint 1955).

In summary, the glacial deposits covering eastern South Dakota end at the Missouri River because that was the limit of glacial advance. But glaciers didn't stop there because of the river. In fact there was no river until ice blocked east-flowing streams, sending them south along the margin of the ice sheet to become part of the longest river in North America—the great Missouri, 2546 miles in length from its headwaters in the Rocky Mountains to its confluence with the Mississippi (2).

President Thomas Jefferson by Rembrandt Peale, 1800 (source).
The Louisiana Purchase was one of Jefferson's greatest accomplishments.

In December of 1803, the United States bought the Missouri River from France as part of the Louisiana Purchase. For only $15 million ($18 per square mile) the young country doubled in size. Six months later, in May of 1804, the Corps of Discovery led by Meriwether Lewis and William Clark started up the Missouri from its confluence with the Mississippi. They had been commissioned by President Jefferson to explore, survey and document the new territory—including its plants, animals, useful resources and human inhabitants. But above all, they were to determine whether the Missouri was part of a water route to the Pacific Ocean.

Travel up the swift-flowing river was terribly slow and arduous. The men paddled, sailed and too often pushed or pulled their boats, including a heavy metal-framed keelboat. (It was sent back down the river from their winter camp, with collections, reports and a map.) It's thought that each boatman ate on the order of nine pounds of meat per day! Fortunately game was abundant (Johnson 2022).

The Corps of Discovery reached the Pacific Ocean in November of 1805, but only after leaving the headwaters of the Missouri, crossing the continental divide, and traveling months by foot and canoe to the Columbia River and on to the coast. Clearly the Missouri did not offer a water route to the Pacific. Even so, it would be an important transportation corridor ... in spite of its treachery.

Navigating Old Misery; from exhibit at USACE Lewis and Clark Visitor Center.

The Missouri, or "Old Misery", was notorious for its unpredictability and lurking hazards. Here's how Joseph Nicollet described his trip on the steamboat Antelope.

"But, notwithstanding the great skill with which the navigation of our boat was managed, and the high power that propelled it, our voyage was sometimes interrupted for weeks, owing to the numerous obstacles presented by the river. It would seem that a Missouri pilot ought to possess not only a quick sight, but an intuitive perception to discover through its turbid waters the channel which yesterday had no existence, presents itself today, and will most probably change tomorrow." (Nicollet 1843)

Hazards included sand bars, snags, and wrecked boats. An estimated 400 steamboats were sunk or otherwise destroyed on the Missouri; the average lifespan of a steamboat was five to seven years (Johnson 2022).

Snags (sunken trees) on the Missouri; by Karl Bodmer c. 1839–1840 (source).

Wrecked steamboat on the Missouri; USACE.

Even after trains and trucks largely replaced boats for transport, the Missouri remained a dangerous river. Large floods were common, causing widespread damage to communities and farmland. But times have changed; the Missouri has been tamed. Between 1933 and 1963, six large dams were built on the river in South Dakota, North Dakota and eastern Montana to provide flood control, irrigation water, hydroelectric power and recreation. About 75% of the river's length in the Dakotas is now reservoir water (Johnson 2022).

In terms of storage capacity Lake Oahe is the largest reservoir on the Missouri. From Oahe Dam near Pierre, SD it extends upstream 100+ miles as the crow flies (modified from Google Earth).

Lewis and Clark Expedition, 150th anniversary issue, 1954 (source).

On a hot day near the end of my trip, I walked four miles sometimes shaded by cottonwoods but usually not and often accompanied by dust and flies, and stood on the bank of a free-flowing stretch of the Missouri River. Why? Because the Missouri means more to me than I first thought.

Memories had been surfacing of a little girl and her younger brother playing Lewis and Clark long ago. Those legendary explorers had struggled up the Missouri, enduring summer heat and mosquitos, surviving winter cold and food shortages, all the while not knowing what lay ahead, what discoveries awaited! Lewis and Clark captured our imaginations, and for me they still do. We lived far from the Missouri then, but now I had a chance to travel where they had traveled, to see the great river flowing as they had.

I started from the parking lot of the Adams Homestead and Nature Preserve north of the Missouri River in the southeast corner of South Dakota. The route followed dirt roads and was well signed. You can tag along on this aerial photo (modified from Google Earth).

Early on we passed Mud Lake, the remains of a meander in the Missouri River before it was tamed (3), and continued past fields being tilled. Then there was a handy rest stop, with a water tub that my field assistant enjoyed in spite of all the flies on her ears (a photo would have been rude). I tried rubbing mosquito repellant on her head—it worked!

A short distance further we reached a viewing platform on the bank of the mighty Missouri.

View downstream. One of the Missouri's nicknames is Big Muddy because its sediment load is huge! (4)

As directed, I looked across the Missouri into Nebraska. Much of the river's broad valley bottom is cultivated but this area looked abandoned, in both the photo below and the previous Google Earth view.

Looking south into Nebraska. The forest in the distance is the valley wall.

Artsy abstract photo for my memory collection :)

Once home I opened the Map of Lewis and Clark's Track, Across the Western Portion of North America to locate the spot where I had visited the free-flowing Missouri. The Corps of Discovery traveled this stretch in late August 1804 after burying Sergeant Charles Floyd, the only death on the expedition (perhaps due to a ruptured appendix). His grave is labeled on the map—Floyds Grave.

From Map of Lewis and Clark's Track. Floyds Grave is right of arrow tip marking my visit (click image to enlarge). Courtesy David Rumsey Map Collection.

Notes

(1) For more about the raging flood vs. glaciers debate and Nicollet's involvement, see Mssr. Nicollet & I consider Glacial Theory and Glacial Beauty in South Dakota.

(2) At their confluence, the Missouri River is longer than the Mississippi River (upstream). By convention the longer river retains its name. Why did the Missouri lose out to the Mississippi? See discussion here.

(3) Nearby McCook Lake (in the upper part of the aerial photo) also is an abandoned meander but is older, being shown on a map dated 1895. Perhaps it's a natural one.

(4) Construction of dams and levees drastically reduced the amount of sediment carried by the Missouri River, to 1% of what it had been (Johnson 2022). Even so, it continues to deliver more than half the silt emptied into the Gulf of Mexico! (more here)

Sources (in addition to links in post)

Flint, RF. 1955. Pleistocene geology of eastern South Dakota. Geol. Surv. Prof. Paper 262.

Gries, JP. 1996. Roadside Geology of South Dakota. Mountain Press Publ. Co.

Johnson, WC. 2022. The Missouri River. Chapter 10 in Johnson & Knight 2022.

Johnson, WC, and Knight, DH. 2022. Ecology of Dakota Landscapes; past, present, and future. Yale University Press.

Nelson, Mike. 2014, Jan 29. Geology: eastern South Dakota in CSMS Geology Post. I also thank Mike for directing me to Flint's 1955 paper.

Nicolett, JN. 1843. Report intended to illustrate a map of the hydrographical basin of the upper Mississippi river. US Senate, 28th Congress, 2nd session, no. 237. BHL

Warren, GK. 1869. General considerations regarding the physical features of these rivers: US Army, Corps of Engineers, Rept. Chief of Engineers, 1868, p. 307-314. Full report online. (Conflicting years are puzzling but real.)

Visiting the Mono Craters with Israel Russell

Do you see wreaths of vapor? Or the lurid light of molten lava? (D. Mayer photo)

Last September I toured the Mono Basin in the company of the great pioneering geologist Israel Russell, author of Quaternary history of Mono Valley, California. He wasn't there in person of course, having left this world more than a century ago. But I had read his report. Russell was an able writer and contagiously enthusiastic about his subject, so his spirit was very much with me.

The Mono Basin lies in far eastern California between the east slope of the Sierra Nevada and the California–Nevada state line. Israel Russell first visited in 1881, in the employ of the US Geological Survey. His stay was brief, being incidental to reconnaissance of Lake Lahontan, the great Ice Age lake. Even so, he became sufficiently acquainted with "the more prominent features of Quaternary history" to know he had to return.

Pleistocene–early Holocene lakes of the Great Basin (Russell 1889). Red box marks glacial Lake Mono. It was later renamed Lake Russell (1).

In the fall of 1882, after finishing his Lake Lahontan project, Russell traveled to the Mono Basin for further study. But he was too late; "the storms of winter compelled a postponement of the undertaking." The following summer he returned with topographer Willard Johnson, who completed a survey of the Basin, and JB Bernadou who made field sketches and assisted in various ways. Quaternary history of Mono Valley was published seven years later, in the 8th annual report of the USGS (2).

In his report Russell invites the reader to travel with him "in fancy" from the mining town of Bodie down into the Basin, along the shores of "intensely alkaline" Mono Lake, and then up to the crest of the Sierra Nevada and the summit of Mt. Dana. I joined him just south of Mono Lake, at the north end of the Mono Craters.

"between the observer [in the Basin] and the steep face of the Sierra there is a range of volcanic cones that attract the eye ... These are the Mono Craters. So perfect are their shapes and so fresh is their appearance that the eye lingers about their summits in half expectation of seeing wreaths of vapor or the lurid light of molten lava ascending from their throats." (All quoted text is from Russell 1889 unless otherwise cited.)

Mono Craters, looking south. Panum volcano at north end, Sierra Nevada in distance. USGS 1971.

Russell knew the Craters were volcanic, but some of their features were strange. "The Mono Craters are composed entirely of ejected matter. Lapilli (a general name for small rock fragments thrown out by volcanoes) form the most conspicuous portion of the cones. There are also several coulées of volcanic rock which flowed out in a molten condition and consolidated on cooling." It was the coulées that puzzled him (3).

Obsidian Coulée rises steeply behind Russell's mule—"the most practicable method of carrying forward work".

The Mono coulées were clearly lava flows, but they were very short, quite thick, and made of rhyolite. "These outbursts of acidic lava are in strong contrast with the overflows of basic rock with which geologists are most familiar ... [which] are frequently quite liquid at first, flow rapidly, and reach a distance of many miles before congealing sufficiently to check their progress."

In fact these coulées didn't flow very far at all, rarely beyond the foot of their cones. And they were 200–300 feet thick, with steep sides and fronts. Russell rightly concluded that the lava had been quite viscous.

"One of the most striking features illustrated by the lava streams of the Mono Craters is that the molten rock came forth in a viscid or semi-fluid condition and cooled rapidly. ... The extruded lava was apparently sufficiently heated to be pasty or semi-fluid, but the temperature was not raised high enough to produce what is usually termed fluidity and thus permit rapid flow."

The Mono Craters also include plugs and domes made of rhyolite. Russell considered them "incipient coulées which were congealed before a definite flow in any direction had been established." He was right about this too.

Looking east at steep fronts of several Mono coulées (Russell 1889).

Same coulées from Nature Trail stop on US 395. High point on left is Crater Mountain, a rhyolite dome.

North Coulée from south shore of Mono Lake; left end was the front of the flow.

North Coulee at a worthy geostop on CA 120. "Even at the present day, after many blocks have fallen and the formation of a talus slope has commenced, the climber finds it extremely difficult to scale these rugged and broken escarpments of glassy fragments."

Today we're taught that magma viscosity is a major factor in its behavior and the resulting landforms. We also learn that viscosity varies with silica content (e.g., Fisher et al. 1997). For example magma containing < 55% silica flows easily, making the familiar "basic" lava flows Russell mentioned. At the other end of the spectrum, magma with > 70% silica flows with great difficulty if at all, and is too viscous even for gases to escape. Instead pressure builds until the magma explodes. Hot incandescent ash races across the landscape searing everything in its path before finally stopping and cooling to form massive beds of welded rhyolite.

As Russell noted, the Mono coulées are rhyolite, high in silica. So why did silici magma ooze out instead of exploding, as we're told it does? Russell didn't have to struggle with this question because so little was known about volcanoes then. It was something for future geologists to puzzle over, and Russell was optimistic they would.

"The range is unlike any other known to the writer, and, so far as can be judged from the reports of explorers, is the only one of its kind in the United States. When the valley in which these craters are situated becomes more familiar to tourists and geologists, they can not fail to be widely known as typical illustrations of mountains formed of acidic lavas".

Mono domes and coulées "formed of acidic lavas" (Marcaida et al. 2019),

If Russell's spirit indeed visits the Mono Basin, it must be a happy one. From the time Quaternary history of Mono Valley was published, "Geologists have been gripped by Mono dome fever ... the chain well deserves the attention succeeding generations of geologists have lavished on it." (Sharp & Glazner 1997).

Those feverish geologists have shown unequivocally that the Mono volcanoes are young. The first may have erupted as early as 90,000 years ago, but most are less than 10,000 years old. In that short time at least 28 rhyolite domes and coulées have emerged (Marcaida et al. 2019). Those in the middle of the chain are oldest. The youngest (and my favorite) is Panum at the north end, a mere babe just 700 years old.

But the question remains: Why did silica-rich magma ooze out of the Mono Craters instead of exploding?  A common suggestion is that Mono volcanoes erupted in two stages. In the first, small fragments (lapilli) are ejected and deposited to form a crater-like cone. Some magma remains in the chamber, specifically magma depleted of explosive gases and still hot enough to flow. In the second stage, "a mass of thick, pasty [rhyolitic] glass oozes up within the crater to form a dome ... The dome may grow so large that it fills its crater and occasionally breaches the ring of explosion debris to flow away as a stream of molten glass, a coulée." (Sharp and Glazner 1997). Wouldn't that be great to see!

Tiny dome inside Panum crater, perhaps an "incipient coulee". Is it still flowing?

As volcano guidebook authors must, Russell addressed the unavoidable question: Are the Mono volcanoes extinct or only sleeping? 

He explained that some are quite young, having erupted after geologically-recent events. "Their last eruption took place after the glaciers had retreated up the cañons of the Sierra. They also are, in part, more recent than the ancient beaches to be seen about the border of the valley, which record former high water stages of [glacial] Lake Mono."

The Mono Craters may have erupted recently geologically-speaking, but for most of us, ephemeral creatures that we are, they're relics of the past. Russell ended his report by tackling this misconception. 

"The [Pleistocene–early Holocene], as compared with the present, appears to have been a time of greatly expanded water surface, increased glacial action, and more energetic volcanic activity. In making such a statement, however, it is evident that we are comparing the events of a day with a whole volume of history. Could we look into the future with as much accuracy as we are able to review the past, it would be evident that changes are now in progress that in time will equal the apparent revolutions [of the past]." (emphasis mine)

Israel Russell (source). "his physique gave to the eye little suggestion of that capacity for sustained effort and endurance without which his more strenuous exploration would have been impossible." (Gilbert 1906)

Notes

(1) There also is a Glacial Lake Russell in Washington, also named for Israel Russell.

(2) Many readers have been captivated by Russell's writing. Early residents of the Mono Basin liked it so much that they paid for a separate printing of his report, to use to attract tourists (Gaines 1984). It was reprinted in 1984 by Artemisia Press, but again sold out. I found a used copy online.

(3) "Coulée" is a Canadian French word derived from the French "couler"— to flow. Beyond that, its meaning varies widely. Coulées can be lava flows, like those of the Mono Basin. In eastern South Dakota coulées are draws, usually narrow with steep sides, where water flows or has flowed. In Washington (state) coulées are huge channels scoured into basalt bedrock by Ice Age floods.

Sources

Fisher, RV, Heiken, G, Hulen, JB. 1997. Volcanoes: crucibles of change. Princeton U Press.

Gaines, D. 1984. Mono Lake's Poet-Geologist. Preface in 1984 reprint of Russell's 1889 report (see below).

Gilbert, GK. 1906. Israel Cook Russell. J. of Geology 14:663-667.

Marcaida, M., et al. 2019. Constraining the early eruptive history of the Mono Craters rhyolites ... Geochemistry, Geophysics, Geosystems, 20, 1539–1556. https://doi.org/10.1029/2018GC008052

Russell, IC. 1889. Quaternary history of Mono Valley, California in USGS 8th annual report (If the USGS PDF is slow to load and read online, try HathiTrust.) Russell's report was printed separately in 1984 by Artemisia Press, Lee Vining, CA (now out of print).

Sharp, RP, and Glazner, AF. 1997 (4th printing 2003). Geology Underfoot in Death Valley and Owens Valley. Mountain Press.
A revised second edition of this guide was published in 2022 (Glazner, Sylvester, & Sharp). Based on the areas I've visited, it seems more science light and the tours more cursory. But of course maps and illustrations are far better. Perhaps buy both.

Cartographer Joseph Nicollet's Eponymous Plant

Nicolletia, Hole-in-the-sand Plant. Van Loon photo.

For those who missed my recent posts about cartographer Joseph Nicollet (here and here), he figured prominently in exploration and mapping of our country. He left France in 1832, intent on surveying the great triangle between the upper Mississippi and Missouri Rivers. Though penniless and with only a few contacts initially, he managed to make three expeditions through the region. The first was privately supported, in part by wealthy fur traders eager for factual  maps. The second and third were funded by the Federal Government, with Nicollet the appointed leader. Not bad for a recent immigrant!

Nicollet's Hydrographical Basin of the Upper Mississippi River From Astronomical and Barometrical Observations was the first accurate map of the region. As the title indicates, he relied heavily on instruments—at that time a novel approach, especially the use of barometry to determine elevation. This was a map years ahead of its time.

Decades later, GK Warren of the Corps of Topographical Engineers referred to Nicollet's map as "one of the greatest contributions ever made to American geography." He suggested Nicollet would have become head of the Corps if had he lived longer.

North end of the Coteau des Prairies from Nicollet's map. Hachure lines show
relief. The entire map—high-resolution and zoomable—is available here.

Joseph Nicollet, date unknown. Source.

Fittingly, Nicollet has been honored in the region he surveyed—e.g., the town of Nicollet in Nicollet County, Minnesota; Nicollet Avenue in Minneapolis; and especially Nicollet Tower on the Coteau des Prairies in northeast South Dakota. (The Tower and Interpretive Center are highly recommended!)

Nicollet Tower west of Sisseton. From the top, the views are wonderful.

Nicollet also was honored with a plant, though not one from his survey area—in fact, not even close. The eponymous plant is Nicolletia occidentalis, the Mojave Hole-in-the-sand Plant. "Mojave" refers to the large desert in southeast California.

The story behind this curiosity began in early 1838, when the US government hired Nicollet to survey the upper Mississippi drainage. In addition to funding, he was given a novice assistant from the Corp of Topographic Engineers—25-year old John C. Frémont, the future Pathfinder. Frémont would lead five expeditions across the American West, and Nicollet's influence is apparent in his maps. The Pathfinder regularly documented locations with celestial observations, and elevation with barometry.

Fremont also collected plants. He had enough training to properly prepare specimens, but for identification, he sent them to experts. After his expedition to Oregon and California in 1843–44, he delivered a batch to John Torrey, botanist for the state of New York.

Frémont's Nicolletia collection, the type specimen. New York Botanical Garden.

Zooming in on packet contents—dried flowers and other fragments.

Torrey's Descriptions of some new genera and species of plants, collected in Captain J.C. Frémont's exploring expedition ... 1843–44 was published as part of Fremont's 1845 report. In the introduction to the Composite family (today's Asteraceae), Torrey noted that "The plants of this family were placed in the hands of Dr. Gray for examination;" This was Asa Gray of Harvard University, who would become one of the greatest American botanists of the 19th century.

It was Gray who named Nicolletia, as Torrey explained. "He has since ascertained another new genus among the specimens ... and we fully concur with him in the propriety of dedicating it to the late distinguished [J.N.] Nicollet, Esq., who spent several years in exploring the country watered by the Mississippi and Missouri Rivers, and who was employed by the United States Government in a survey of the region lying between the sources of those rivers."

Nicolletia is a tough desert plant with spines and slightly succulent foliage. Van Loon photo.

In his description of the genus, Gray detailed the various plant parts using botanical terms, for example, "Branches of the style terminated by a subulate hisped appendage. Achenia elongated, slender, canescently pubescent." But for some reason, in the midst of all this verbage he wrote: "A humble, branching (and apparently annual) herb." The type specimen (basis for the species description) was collected "On the banks of the Mohahve river, growing in naked sands; flowering in April."

A classic composite; what looks like one flower is a head with both ray and disc flowers. Sheriff Woody photo.

When sand collects around the base of the plant, it appears to rise from below the surface, hence the name Hole-in-the-sand Plant. But Nicolletia is easier to say and to me, more appealing.

Sources

Cohen, PE. 2002. "A veritable landmark in cartography: the sources of the Mississippi; Hydrographical Basin of the Upper Mississippi River." in Mapping the West. Rizzoli Publications New York.

Torrey, J. 1845. Descriptions of some new genera and species of plants, collected in Captain J.C. Frémont's exploring expedition to Oregon and North [Upper] California, in the years 1843—'44. BHL (Nicolletia p. 315-16.)

Mssr. Nicollet & I consider Glacial Theory in northeast South Dakota

Courtesy NASA.

During my visit to northeast South Dakota last fall, I bumped into the great surveyor Joseph Nicollet and discovered we had similar goals. As aspiring geologists we hoped to expand our knowledge of the discipline. We wanted to see and understand the magnificent Coteau des Prairies. And we both struggled to picture today's prairies buried under a thick sheet of ice, though for different reasons.

Thanks to some deep memory, I knew eastern South Dakota was once glaciated but had given the subject little attention. In contrast, glaciation (or rather its possibility) was of great importance to Nicollet, but he didn't know what to think. It was very difficult to accept on such a scale. Our contrasting reactions were understandable given our visits were 183 years apart.

Nicollet Tower near Sisseton, SD. I "met" Joseph Nicollet in the interpretive center at the base.

In 1832, at age 46, Joseph Nicolas Nicollet left France for reasons unclear—perhaps political, perhaps financial, or perhaps because he had become passé, démodé. Though widely recognized as one of the best astronomers and surveyors in the country, his skills were no longer in demand. Much of France had been adequately mapped. This was not the case in the United States. Most of the young country remained only nominally surveyed. Existing maps often were unreliable.

To Nicollet, the opportunities were obvious. Even before he departed for the US, he had decided he would survey and map the great triangle between the Mississippi and Missouri Rivers, as far north as Lake Superior—a region of French influence and French speakers. Seriously, monsieur?! How will a slightly-built, well-educated and cultured but penniless Frenchman survive in this wild unsettled territory? Mais qu'importe; he would make it happen.

Portrait of Joseph Nicolas Nicollet, date unknown (source).

Nicollet's area of interest; annotated excerpt from 1969 USGS topographic relief map.

In 1835, Nicollet was in St. Louis, at the confluence of the Mississippi and Missouri, campaigning for a survey of the upper Mississippi. He secured the support of the American Fur Company (always eager for better maps), and the wealthy Choteau family—fur traders and merchants. The next year he traveled by steamboat to Fort Snelling, and from there, surveyed the upper Mississippi drainage by canoe with Ojibway and French-speaking halfbreed guides. Back at Fort Snelling, Nicollet refined calculations of latitude and longitude from his celestial observation data, and produced a map of the territory he had covered. When he returned to Washington DC, he found that news of his excellent map had already arrived.

Among other things, Nicollet fixed errors made 30 years earlier by Army officer and explorer Zebulon Pike. Most egregious was Pike's erroneous placement of the mouth of the Crow Wing River, off by 27' latitude. As a result, everything upstream was too far south and west, contracting "the extensive region between the Mississippi and the Missouri; so that there was not (so to speak) room for the intermediate territories which I had explored." (This and all Nicollet quotes below are from the 1843 report accompanying his map of the upper Mississippi drainage).

Recognizing Nicollet's skill and zeal for accuracy, the US government, through the Army Corps of Topographical Engineers, funded additional survey, and provided an assistant—a young officer just 25 years old named John C. Frémont, the future Pathfinder. It was an excellent investment. Nicollet would lead two expeditions in the upper Mississippi drainage, determine latitude and longitude for some 90,000 points, and produce Hydrographical Basin of the Upper Mississippi River, the first accurate map of the region.

Excerpt from Nicollet's map, published after his death in 1843; blue labels added.

The first expedition, in 1838, went well enough that Nicollet was able to secure funding for a second, to areas farther north, including Devil's Lake (in today's North Dakota) and the intriguing Coteau des Prairies. On April 4, 1839 Nicollet, Frémont, and botanist Charles Geyer left St. Louis aboard the American Fur Company's steamboat Antelope, bound for Fort Pierre 1270 miles upstream. The Missouri was very low and they repeatedly ran aground, sometimes waiting several days for the water to rise. But there were benefits. Whenever the Antelope was firmly stuck, the scientists went ashore in search of discoveries.

Nicollet would climb banks and slopes above the river to study exposed rock layers, often fossil-rich. He hoped to assign them to the stratigraphic classification used in Europe. Intriguingly, east of the river, at the top of slopes where the land flattened, he inevitably found not layered strata but jumbled accumulations of gravel, cobbles, and even large boulders, all derived from rock unlike any in the area. These kinds of deposits—unstratified and distantly derived—had also been described in Europe, where they were called diluvium or erratic deposites (old spelling of deposit).

After 69 days the Antelope finally reached Fort Pierre, on the west side of the Missouri. It had rained heavily the night before, and water was surging off the largely barren land into the river. The wet clay-rich soil was so slimy, soft and sticky that it was impassable, even on foot. Nicollet noted in his journal that travelers reported similar conditions extending far to the west—lands "so sterile that they are referred to as the Great American Desert."

Yet just across the river to the east, the landscapes changed dramatically: "the vast spaces opening to your gaze, the astonishingly richer vegetation, the smoother undulations breaking the monotony, the purity of the water in the streams and rivers flowing into the Missouri, the nature of the woods shading them—everything proclaims a favorable change in the physical aspects of the country."

The "astonishingly richer vegetation" east of the Missouri has been largely replaced with cultivated fields.

After 18 days at Fort Pierre preparing for prairie travel, Nicollet and his party headed northeast. He found the country beautiful and surprisingly novel. "It is neither a mountainous, nor a hilly, nor an absolutely flat country; exhibiting undulations of the surface that are not entitled to these usual appellations." Early explorers, first French, then British, "were so forcibly impressed with this novelty in the appearance of the topography, that they employed new names to designate it. Hence, we have the expressions: Coteau des Prairies, Coteau des Bois, Hauteurs des Terres, and rolling, flat, or marshy prairies."

As they traveled, one geological feature was ever-present—jumbled accumulations of gravel, cobbles, and boulders like those Nicollet had seen earlier above the Missouri River. He described it as "a vast deposite of sand, gravel, pebbles, and clays ... and masses of rocks transported to a distance from their original position, usually called erratic blocks. This deposite always occurs between the vegetable soil and the rocky strata of all ages that constitute the geological basis of each section of country."

Because the deposits were quite jumbled and found immediately below the soil, they probably had arrived recently (geologically speaking). But from where and how? Nicollet hesitated to draw conclusions. "It is difficult to determine the direction whence the materials of the erratic deposite came. The presumption is, judging from the nature of the erratic blocks—the analogues of which are found in higher latitudes—that they were brought from the north to the south." In this presumption, Nicollet was correct.

Erratic blocks as riprap; east shore of Lake Oahe on the Missouri River.

Erratic blocks poking through "vegetable soil" on the Coteau des Prairies.

Nicollet likely knew of erratic deposites prior to his expeditions. In St. Louis in 1835, he met artist and ethnographer George Catlin, who had toured the country west of Fort Snelling as far as the Coteau des Prairies. Catlin was a bit of a geologist himself, curious about the origins of the landscapes he painted. Surely the two men discussed the puzzling deposits, which were of great interest to Catlin. In fact, he presented a paper on the subject to the Boston Society of Natural History.

"There are thousands and tens of thousands of bowlders scattered over the prairies at the base of the Coteau ... I believe that the geologist may take the different varieties which he may gather at the base of the Coteau in one hour, and travel the continent of North America all over without being enabled to put them all in place; coming at last to the unavoidable conclusion, that numerous chains or beds of primitive rocks have reared their heads on this continent [these are uplifted mountains], the summits of which have been swept away by the force of the diluvial currents, and their fragments jostled together and strewed about, like foreigners in a strange land ..." (Catlin 1840; emphasis mine).

The great Deluge in northern Europe (Figuier 1863).

Several of Catlin's "foreigners in a strange land" at Sica Hollow State Park.

Catlin's thinking was shaped by the widely accepted Diluvial Theory, which proposed a catastrophic flood of global proportions. The strongest evidence came from the Bible; without biblical narratives, such an immense and powerful flood would be difficult to justify.

However by the time Nicollet was studying erratic deposites in North America, a new theory had come to the fore. Louis Agassiz's Glacial Theory nicely explained why features associated with today's glaciers—striations, polish, erratic deposites, and such—were also found far from any ice. During "glacial epochs" or "ice ages", when the Earth's climate was much colder, glaciers and ice sheets extended lower in elevation and farther south.

But climate change and ice ages were radical new ideas, and very difficult to accept. Poor Nicollet had to write his report in the midst of a raging debate—Diluvial vs. Glacial. Wisely, he described the vast erratic deposites but took no position on their origins. "The region comprised within my map is covered by species of deposite of the kind for a long time known by the name of diluvium; but as this word implies a theoretic idea as regards the accumulation of such deposites, the cause of which is still open to controversy, it is now very generally abandoned, and the designation of erratic deposites, among others, adopted in its stead. I have, therefore, used the latter expression ..."

Perhaps you are wondering, as Nicollet surely did, whether the erratic deposites east of the Missouri River explain the lush prairie grasses there. If so, how did the Great American Desert to the west escape the flood? Or was it an ice sheet? How nice if Mssr. Nicollet's spirit were following this blog. He would soon learn of today's thinking about erratic deposites. And he might be pleased to know that for the wonderful Coteau des Prairies, le mystère demeure.

 "The head of the Coteau is very near us. It presents an imposing mass ... beautiful to the eyes which have seen nothing but plains and rolling plateaus. It is the Alps of this region." (Coteau from north, by Bigfitz79)

Sources

Bray, MC. 1970. Joseph Nicolas Nicollet, geologist. Proc. Am. Phil. Soc. 114:37-59.

Bray, MC. 1980. Joseph Nicollet and his map. American Philosophical Society, Philadelphia.

Catlin, George. 1840. Account of a journey to the Coteau des Prairies, with a description of the red pipe stone quarry and granite boulders found there: Am. Jour. Sci., 1st ser., v. 38, p.138-146.

Figuier, L. 1863. (Bristow, LH, ed. 1872). The World Before the Deluge. Accessed Jan 2023.

Hansen, B. 1970. The early history of glacial theory in British geology. J. Glaciology. Accessed Jan 2023.

Johnson, WC, and Knight, DH. 2022. Ecology of Dakota Landscapes; past, present, and future. Yale University Press (reviewed here).

Nicolett, JN. 1843. Report intended to illustrate a map of the hydrographical basin of the upper Mississippi river. US Senate, 28th Congress, 2nd session, no. 237. Accessed Jan 2023. A high-resolution zoomable version of Nicolett's map is available online.

House Range: more than a Tertiary fault block

Sun sets on the House Range, west central Utah. Thanks to Mike Nelson for photo and info.

Last month I wrote about my stay in the House Range, a large mass of rock that started as sediments in a Cambrian sea. Now 500 million years later, they stand nearly 10,000 ft above sea level. On the steep west face the layers are obvious. On the opposite side we see gentle slopes that disappear below the surface of the valley to the east.

Steep west face, with the "well-defined stratification" observed by Capt. JH Simpson in 1859. Because the crest looked like structures, he called these mountains the House Range.

Road leading to the east side of the House Range. Note the gentle slopes. The pale rock in the draw on the right is not sedimentary.

Pioneering geologist Grove Karl Gilbert visited the House Range in the early 1870s, as part of GM Wheeler's Surveys West of the One Hundredth Meridian. The asymmetry of the uplift blew his mind. "... the beds exhibit in cross-section but a single direction of dip" (italics mine). He had expected something like the Appalachian ranges, whose structure was considered typical of all mountains. "... it was only with the accumulation of difficulties that I reluctantly abandoned the idea." (Gilbert 1875)

Gilbert's cross-section through the House Range (1875).

Of course surprises were to be expected; geology was still a young science. For example consider orology—the science of mountains (now orogenesis). In Gilbert's time, geologists struggled to explain how mountains formed even in a very general way. Their theories ranged from crustal wrinkling as the Earth cooled to fiery forces underground.

Gilbert admitted he was far from understanding orology in the "Basin Range System" (now Basin and Range Province). But after studying so many ranges he could shed some light on the subject. He suspected the House Range was bounded on the west by a steep normal fault, which had tilted strata downward to the east. And whatever caused this uplift must have been operating on a grand scale, for he had seen similar structures over a huge area.

The Basin and Range Province overlaps the Great Basin but is larger, mainly to the south (sources differ on boundaries). In the BRP, ranges generally trend northerly, are bounded by normal or listric faults, and are separated by sediment-filled basins.

Gilbert also discovered "cross faults" in the House Range. He included one in his diagram of the west face (below), which emphasizes the southerly component of overall dip. In several places, strata have been disrupted by faulting. Gilbert shows this by labeling beds of quartzite ("q", looks like "g") and limestone ("l"). Near Notch Peak the quartzite and limestone are higher than they are at Dry Pass to the north, contrary to what we would expect based on dip. Gilbert had no explanation for these faults, except that they probably predated uplift of the House Range (Hintze & Davis 2003).

Click on image to view displaced quartzite and limestone (Gilbert 1928).

Today geologists generally agree that Basin and Range orogenesis is due to stretching of the continent, as the Pacific and North American plates grind past each other along transform faults (DeCourten & Biggar 2017; see Busby's Walker Lane diagram). Extension is thought to have started 30–40 million years ago, and so far has doubled the distance between Salt Lake City and Reno. It continues, as evidenced by earthquakes and precision GPS measurements. As Gilbert suspected, this is orogenesis on a grand scale—from eastern California to central Utah, and from southern Oregon and Idaho to northern Mexico.

Gilbert also was right about the relative age of the cross faults in the House Range (Hintze & Davis 2003). They were part of earlier mountain building (late Jurassic through Cretaceous), when western North America was being compressed as the Farallon plate dove under the west coast. The result was 200+ million years of orogenesis, producing the Sierra Nevada, Rocky Mountains, and the lesser known Sevier orogenic belt (DeCourten & Biggar 2017).

During the Sevier Orogeny strata were shoved eastward, sometimes great distances, along low angle thrust faults (detachments). Seismic exploration has shown that the central House Range is underlain by several shallow-dipping major faults formed by regional, easterly-directed thrusting, most likely during the Sevier Orogeny (Stoeser et al. 1990).

Non-sedimentary rocks near the base of the House Range's west face.

Oddly, Gilbert seems to have ignored a prominent geologic feature of the House Range, though he may have hinted at it in one sentence: "The rocks are almost wholly sedimentary" (italics mine) (Gilbert 1928, p. 74). The topographic map (Plate 31) provides another hint:

Note "Granite Canyon" northeast of Notch Peak. It's now called Miller Canyon.

Finally, Gilbert's diagram of the west face shows steeply tilted strata below and just north of Notch Peak, but with no explanation (below; red annotations mine).

Are the lower rocks in this photo Gilbert's steeply tilted strata?

In 1905, the eminent paleontologist Charles Doolittle Walcott came to the "great House Range" to study its fossil-rich rocks, and to establish "the interrelations of the strata and faunas in the North American Cordilleran area". In his 1908 report, he included photographs of exceptional sites so that "geologists and paleontologists who have not had an opportunity to see the sections may get an idea of the completeness of the exposures of the strata in the Cordilleran area." One such site was the House Range.

Notch Peak and the west face of the House Range. "... an intrusive mass of granite porphyry is intruded into the Cambrian beds on the north side of the peak (left side)." Aside from this caption, Walcott made no mention of the intrusion in his report.

Being a huge fan of GK Gilbert—such an observant open-minded adventurous geologist!—I have to wonder why he omitted this obvious granitic intrusion in his reports on the House Range. Maybe he just didn't want to struggle with yet another puzzling geologic feature.

But now much of the puzzle has been solved. "The Notch Peak intrusive presents a case study of the whole gamut of magma emplacement ... Seldom can one find in so neat an area the geologic record of such a variety of processes generated by a single intrusive body," wrote Arthur L. Crawford, Director of the Utah Geological and Mineralogical Survey in 1958. No longer do geologists ignore it (e.g. Gehman 1958, Stoeser 1990, DeCourten 2003).

Notch Peak intrusive viewed from east. Intrusions by definition form underground. If we surface creatures can see them, something must have happened—in this case, uplift of the House Range and  erosion.

The Notch Peak intrusive is composed of quartz monzonite, sometimes called granite (they differ slightly in composition). It's assumed to be Jurassic in age (dated at 193–143 Ma), is about 3 mi in diameter or 2.5 x 4.5 mi in area, and may be a laccolith. Other features include aplite dikes and sills intruding adjacent sedimentary rocks, zones of pegmatite, crystal-lined cavities, and mineral-rich skarn.

The beauty of skarn!—from Osgood Mountain intrusive (into carbonates), Nevada. Like Notch Peak skarn, it contains tungsten and molybdenum. James St. John via Flickr.

Intrusions have created great wealth in Nevada and Utah, in the form of ores. As molten magma ascends and crystallizes, hot fluids are expelled. These circulate and dissolve surrounding rock. If conditions are right, new minerals precipitate out in sufficient quantities to produce ore, where "one or more valuable substances can be mined at a profit." (Mineral Resources)

If magma intrudes carbonates—limestone or dolomite—it often creates skarn when saline metal-rich fluids alter the host rock to form new minerals. In the House Range, the Notch Peak intrusive had ample opportunity to alter limestone. The resulting skarn contains tungsten and molybdenum in moderate concentrations (Stoeser 1990).

Head of Miller Canyon: "FEDERAL MINING CLAIM ... ABSOLUTELY NO PROSPECTING ALLOWED".

Note

Here's a simple timeline for the House Range. For dates, check this geologic time scale.

Paleozoic Era, Cambrian Period: Marine sediments accumulate to great thickness off the coast of Laurentia.

Later Mesozoic Era: Sevier Orogeny deforms sedimentary rocks in the area of the future House Range. Notch Peak quartz monzonite intruded into sedimentary rocks during Jurassic Period.

Cenozoic Era, Tertiary Period (continuing to today?): Continental extension with block faulting uplifts the House Range. Erosion sets in, eventually exposing the Notch Peak intrusive.

Souces

DeCourten, F. 2003. The Broken Land; adventures in Great Basin geology. U Utah Press.

DeCourten, F. 2022. The Great Basin Seafloor. University of Utah Press. Supplemental Field Guide (PDF) available online.

DeCourten, F, and Biggar, N. 2017. Roadside Geology of Nevada. Mountain Press Publishing Co.

Gehman, Jr, HM. 1958. Notch Peak intrusive, Millard County, Utah. Geology, petrogenesis, and economic deposits. UT Mineralogical & Geological Survey Bulletin 62. PDF

Gilbert, GK. 1875. Report upon the Geology of portions of Nevada, Utah, California, and Arizona, examined in the years 1871 and 1872 in Wheeler, GM. Report upon United States Geographical surveys west of the one hundredth meridian v. 3. Washington [D.C.], G.P.O. BHL.

Gilbert, GK. 1928. Studies of Basin Range structure. USGS Professional Paper 153. PDF

Hintze, LF, and Davis, FD. 2003. Geology of Millard County, Utah. UT Geo. Surv. Bull. 133. PDF

Simpson, JH (US Army). 1876. Report of explorations across the great basin of the territory of Utah for a direct wagon-route from Camp Floyd to Genoa, in Carson Valley, in 1859, by Captain J. H. Simpson ...: Making of America Books, U Michigan.

Stoeser, DB, et al. 1990. Mineral resources of the Notch Peak Wilderness Study Area. US Geological Survey Bulletin 1749. GPO. PDF

Walcott, CD. 1908. Cambrian sections of the Cordilleran area, in Cambrian Geology and Paleontology. Smithsonian Misc. Collections 1910, v. 53 no. 5:167–230. BHL