Back to Lake Lahontan, with a guy who knows it well

Lake Lahontan (pale gray) is "a large lake which flooded a number of the valleys of northwestern Nevada at a very recent geological date, but now has passed away."

Last May, I visited Lake Lahontan in the company of pioneering geologist Israel Charles Russell. Of course neither was physically present. The lake passed away c. 10,000 years ago, and Russell died in 1906. But Lahontan left behind abundant relics—sediments, shorelines, gravel bars, tufa deposits and more. Guided by Russell's spirit, I was able to "restore in fancy" landscapes very different from today's high desert (quotes are Russell's words unless noted otherwise).

Today's northwest Nevada is a harsh and arid land. "The mountains are rugged and angular, usually unclothed by vegetation. The valleys, even more dreary than the mountains ... form a picture of desolation and solitude." But just 13,000 years ago the basins were flooded, forming "a single irregular water-body" with islands and peninsulas that "bristled with barren and rugged mountain ranges".

Northwest Nevada today. Google Earth, 2021.

Northwest Nevada 13,000 years ago (Matthew Trump).

Israel Russell and I met two years ago in the Mono Basin, in eastern California. He had worked there in the mid 1880s as a geologist with the US Geological Survey. His Quaternary History of the Mono Valley was published as part of the Survey's annual report in 1889.

As well as explaining geology, Russell described with great enthusiasm the beauty, drama and novelty of the landscapes. Citizens of the tiny town of Lee Vining were so taken by his prose that they requested an independent printing of Quaternary History from the USGS, which they would use to entice tourists. It was reprinted in 1984, by Artemisia Press of Lee Vining (still a small town). I found a used copy online.

With Russell's report in hand, I toured volcanoes, relic terraces, glacial features, and Mono Lake—a little lake with no outlet and water so alkaline that one can float on the surface. But it was very different during ice age times, as Russell explained—"a nearly unbroken water surface 28 miles long by 18 miles broad" fed by glacial meltwater, and overflowing to the north. He called it "Lake Mono" to distinguish it from today's relic. Fifty years later it was christened "Lake Russell", a fitting tribute (Putnam 1949).

Lake Mono (now Lake Russell) back when Sierra Nevada glaciers reached the basin (Russell 1889).

About a year ago, I briefly visited the remains of another ice age lake nearby, one contemporaneous with Lake Russell but much larger—Lake Lahontan. When I learned that Russell had studied it too, I immediately made plans to return. From a rare book store, I ordered his monumental Geological History of Lake Lahontan. His words added much to the landscapes I saw—details, highlights, understanding, appreciation.

Russell did not discover Lake Lahontan, nor did he name it. The first to allude to it in a publication may have been John C. Fremont, who crossed this way in 1843 and 1844, and described tufa in his report. But as Russell later wrote,

"... although [Fremont] noted the presence of tufa deposits about Pyramid Lake, and published a sketch of the tufa-coated island ... he does not seem to have recognized that his route led through the desiccated bed of an ancient inland sea."

"Like other rocks along the shore, [the pyramid] seemed to be incrusted with calcareous cement" (Fremont 1845).

Fifteen years later, geologist Henry Engelmann with the 1859 Simpson Expedition very much recognized the ancient inland seas they crossed:

"That the country adjoining Salt Lake and Carson Lake has once been covered with water must strike every observer ... regular 'benches' of shingle and detritus have been formed along the surrounding heights ... They frequently appear as distinct water-marks of equal height all around" (Engelmann 1876; italics mine).

Fort Churchill State Park; note terraces on slope on left—Engelmann's "distinct watermarks".

The first detailed geological study of  Lake Lahontan was done in 1867, by Clarence King, Arnold Hague and SF Emmons as part of the "Geological Exploration of the Fortieth Parallel". It was King who named the "great extinct sheet of water" in honor of Baron de LaHontan, the "gallant French explorer" of the Mississippi headwaters in the late 1600s. However, King's survey was limited to a belt 100 miles wide, leaving large areas of Lahontan to the north and south needing survey and study.

By 1880, King had become Director of the new US Geological Survey, and Grove Karl Gilbert, head of the Great Basin division, had begun his survey of ice age Lake Bonneville in Utah. There he was assisted by a recent hire—Israel Russell. Gilbert was so impressed with Russell's skills and motivation that he gave him his own project—Lake Lahontan in Nevada. In three fields seasons Russell would study and map the entire basin, more than 20,000 square miles, becoming "the first to read [Lahontan's] story, trace its history, and recognize the numerous agencies that varied its life and led to its death."

"Routes traveled [red & pale blue lines] and areas surveyed" (Russell 1885).

Russell started with a solo reconnaissance in 1881. It lasted seven months "during which about 3500 miles were traversed in the saddle." Having crossed the ancient lake multiple times in various directions, Russell was able to decipher much of its history. Details were added during the field seasons that followed, through observation and instrumental work with the help of a topographer and two geological aids. Their studies were extensive, thorough and diverse.

They delineated, measured and made detailed drawings of lakebed sediments. They mapped topography, paying special attention to the geometry of basins flooded by Lahontan's waters. They sampled today's lakes to determine their chemistry and origins. When opportune, they collected fossils and the three types of tufa: lithoid, thinolitic and dendritic. And they measured, mapped, sketched and interpreted relic features left by the ancient lake—beaches, shorelines, gravel bars, spits and more. My hope was to stand where they had stood and see what they had seen, while imagining the waters of an immense lake sparkling in the sun.

See the sparkling lake?

The northeast part of Lake Lahontan lies due west of Laramie, a 770-mile drive on Interstate Highway 80. My first stop was Rye Patch, on the Humboldt River.

"the Humboldt River flows in a channel that it has excavated in Lahontan sediments since the last desiccation of the ancient lake. ... at Rye Patch the river flows a little more than two hundred feet below the general level of the desert. ... Throughout this portion of the cañon the tripartite division of the strata exposed in the steep banks is easily distinguished."

"Lahontan sediments, Humboldt Cañon, near Rye Patch, Nevada" (Russell 1885).

The Humboldt River at Rye Patch was dammed in 1936, but the reservoir was quite low when I visited. From the campground, I viewed Lahontan sediments in the canyon walls just above the water, with a typical "angular unclothed" range rising above.

Lahontan sediments, Humboldt Cañon, near Rye Patch, Nevada, 2026.

I saw what looked like the "tripartate division" described by Russell (click on image above): pale clays at the base, which settled when the lake was deep; then a darker bed of gravel washed in when the lake was shallow and much smaller; and on top, more clays when it again filled. These three layers were important evidence for Russell's conclusion that "two high-water stages [were] separated by a time of desiccation" (still widely accepted).

Detailed section showing Lahontan sediments near Rye Patch (Russell 1885).

The next day I awoke to rain. So I toured Lake Lahontan by van searching for relic features. From Rye Patch I drove west and then south on I-80, following the Humboldt River to where it ceases to exist, the last of its trickles having sunk into the Carson Desert (as do the Carson and Truckee Rivers nearby).

I drove for miles across "broad silent plains of desolation" while thinking of Russell and his crew working in the heat of summer, without shade, and with no water except for the rare pool in a playa. That was too alkaline to drink of course, but as their tests showed, it also was too fresh—not salty enough to be the last remnants of Lahontan. The great lake must have evaporated entirely.

Humboldt Lake in Humboldt Sink (Famartin, arrow added).

Playa up close: "tessellated pavements of cream-colored marble"

When the rain let up, I decided to look at gravel. Being a highly irregular lake occupying multiple basins connected by narrow straits, Lahontan left behind a lot!

"Accumulations of gravel in the form of bars and embankments occur at many points along the ancient shores ... These are seldom straight, but curve with beautiful symmetry, each gracefully bending ridge marking the course of a current in the waters of the ancient lake in which it was formed."

Out of convenience, I stopped at a quarry. No gracefully bending ridges were visible, but I enjoyed wandering around and contemplating the handiwork of Lahontan's currents. And the size of the deposit was astonishing!

Gravel quarry below Mopung Hills, east of Carson Sink.

Immense gravel bar, shaped by quarrying.

The next day I awoke to sunshine, and again departed Rye Patch on I-80. After crossing the subtle divide between Humboldt and Carson Sinks, I turned south on US Highway 95. My destination was Russell Pass on the shore of Lake Lahontan, at the south end of the Carson Basin. It's clearly marked in Roadside Geology of Nevada (DeCourten & Biggar 2017) and on the local USGS topographic map. There I would commune with Russell's spirit and view the lake phenomena he described.

About 18 miles south of Fallon, a notch came into view. Everything looked right—bold rugged volcanic rocks, some encrusted with tufa, and slopes girdled with terraces. But at the pass was an unexpected sign, and no place to pull off.

"ENTERING Gabbs Valley Watershed"

I continued south a short distance to the Russell Pass Landfill, where I checked several maps. Indeed, Russell Pass is on the divide between the Carson and Gabbs Watersheds. Confident I had visited Russell Pass, I turned around and began my search for Russell Spit.

When Lake Lahontan was full, the pass and adjacent highlands were an island. On one side was a narrow strait "through which the currents must have swept with great force" given the impressive group of gravel bars and spits that formed.

"Gravel embankments on south border of the Carson Desert, Nevada" [arrow mine].

Plate XIX above, by topographer WD Johnson, was one of the more exceptional illustrations in Russell's Monograph. Roger Morrison included it verbatim in his report on the southern Carson Desert (1964). By that time, the gracefully curving gravel bar (white arrow) east of the large playa was known as "Russell Spit" but exactly when the pass and spit were named appears to be lost (I'm still searching). It must have been before 1951, when the Russell Spit 7.5' topographic map was first published.

From the highway, I turned off at a sign for the Top Gun Drag Strip, where races were underway (audibly obvious). On excellent gravel roads I explored as far south as a huge gravel quarry, where I concluded I didn't know what to look for. Or could Russell Spit be gone? I turned around.

Volcanic rock and tufa, with gravel everywhere.

I stopped to examine pinnacles of volcanic rock and large blobs of tufa. Based on what I read and saw in the Monograph, it looked like dendritic tufa, "by far the most abundant of all the chemical deposits of Lake Lahontan."

"Dendritic tufa deposited on a cliff" (Russell 1885).

Dendritic tufa near Russell Pass, 2026.

Then I looked east across the highway and spotted the terraces Russell saw when he was here, horizontally scored in soft volcanic rock.

Ancient shorelines—"the most common of the records inscribed".

With that, my search for Russell Spit came to an end—unfulfilled perhaps, but hardly disappointing. I had stood where Russell stood, experienced the gravel he had experienced, gazed on tufa-coated volcanic rocks and wave-cut terraces as he had, all the while "restoring in fancy" Lake Lahontan sparkling in the sun.

Sources

David Rumsey Map Collection. Geological History of Lake Lahontan, maps and illustrations.

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

Engelmann, H. 1876. Geological report of country from Fort Leavenworth to the Sierra Nevada, pages 247–336 in Simpson, JH, et al. 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. BHL

Fremont, JC. 1845. Report of the exploring expedition to the Rocky Mountains in the year 1842, and to Oregon and north California in the years 1843-'44. Internet Archive

Morrison, RB. 1964. Lake Lahontan: geology of southern Carson Desert, Nevada. USGS Prof. Paper 401.

Putnam, WC. 1949. Quaternary geology of the June Lake District, California. GSA Bull. 60:1281–1302.

Russell, IC. 1885. Geological history of Lake Lahontan. USGS Monograph 11.

Russell, IC. 1889. Quaternary History of the Mono Valley, California. Internet Archive

By the Shores of Lake Lahontan

Camping on a different kind of beach.

Beachcombing through tufa, not sand.

Last fall, on my way home from California, I drove through northwest Nevada intending to make several brief geostops on the shores of Lake Lahontan. But it was so interesting and so curious that I stayed over two nights. By doing so, I was able to follow in the footsteps of one of the great pioneering geologists of the American West—Israel C. Russell.

I met Russell several years ago in the Mono Basin, not far west of Lake Lahontan. Guided by his spirit, I toured the basin seeing landscapes through his eyes and his words (Russell 1889). He was a terrific writer, and that was a time when geologists weren't constrained by today's conventions of scientific writing. It was wonderful to share his awe and appreciation for the novel geologic features he found.

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)

In 1880, Russell joined Senior Geologist Grove Karl Gilbert of the US Geological Survey in a study of what were thought to be relic shorelines, across a huge area in western Utah. Impressed with Russell's diligence and field skills, Gilbert gave him his own project—a survey of similar features to the west in Nevada It would commence the following year.

During the first field season, Russell made a geological reconnaissance "during which about 3500 miles were traversed in the saddle" (all quotes his unless noted]. That winter he prepared a "Sketch" of his findings, starting with a description of the region—expansive, harsh, unusual in the extreme, and "standing in marked contrast in nearly all its scenic features with the remaining portions of the United States."

"The traveler in this region is no longer surrounded by the open, grassy parks and heavily-timbered mountains of the Pacific slope, or by the rounded and flowing outlines of the forest-crowned Appalachians, and the scenery suggests naught of the boundless plains east of the Rocky Mountains or of the rich savannas of te Gulf States. He must compare it rather to the parched and desert areas of Arabia and the shores of the Dead Sea and the Caspian."

Though unlikely to attract "the pleasure-seeker", the region offered a "peculiar fascination" to geologists, for two reasons. First, "the absence of vegetation gives such unusual facilities for investigation". Often not a single tree can be seen for hundreds of miles, and only the rare robust sagebrush offers any hope of shade. Rock and soil are well-exposed.

The barren range beyond the playa was one of Lahontan's many islands and peninsulas.

Second, "the character of the problems to be solved" was irresistible. This was an area rich in geologic novelties, Lake Lahontan being a fine example. Water is scarce to non-existent, and more than a few travelers have chased mirages, gagged on alkaline muck, and perished from thirst. Yet a host of scattered shorelines, tufa deposits, and gravel bars suggest Lahontan was once a huge freshwater lake sparkling in the sun.

Lake Lahontan in its prime, just 13,000 years ago (source).

Routes traveled [red lines] & areas surveyed (Russell 1885); source.

Russell and various assistants would spend two field seasons studying and measuring Lake Lahontan. They determined the elevations of basins (the old lake bed) and terraces on the slopes above (shorelines). They sketched ancient gravel bars and sand spits, and collected samples of the various types of tufa. And they surveyed and mapped nearly 8500 square miles. The result was monumental: Geological History of Lake Lahontan, a Quaternary Lake of northwestern Nevada; Monograph 11 of the US Geological Survey.

"Depth of Lake Lahontan at highest water stage" (excerpt, note depth measurements); source.

"A characteristic specimen of thinolite" [a controversial type of tufa]; source.

From "Map of Lake Lahontan" (c. 20 x 32 inches in its entirety). Note shaded relief overlying contour lines—subject of a future post.

During my visit last year, I toured a northern arm of Lake Lahontan—today's Black Rock Desert and "Lake" Winnemucca to the south.

Black Rock Desert playa is open to driving, fireworks, camping & more (I stayed on the shoreline above). 

From the Black Rock Desert, I drove south along today's Lake Winnemucca, and stopped at a large tufa tower next to the highway. Tufa is sometimes described as a porous limestone; it forms where freshwater meets carbon-dioxide-rich waters, such as springs, streams, and lakes. In his monograph, Russell described three types and partially clarified an "embarrassing" earlier hypothesis for thinolite.

Tufa tower along NV Hwy 447.

Tufa up close.

Lake Lahontan shorelines above today's mostly-dry Lake Winnemucca.

With that stop my visit to Lake Lahotan came to an end. It was much too brief, and I left determined to return.

"The bare mountains reveal their structure almost at a glance, and show distinctly the many varying tints of their naked rocks."

Sources

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

Russell, IC. 1885. Geological History of Lake Lahontan, a Quaternary Lake of northwestern Nevada; Monograph 11 of the US Geological Survey.

Russell, IC. 1889. Quaternary history of Mono Valley, California (in USGS 8th annual report). Russell's report was reprinted in 1984 by Artemisia Press, Lee Vining, CA.

Geohopping across Nevada

Burners at incipient plate boundary in western Nevada. Are they waving California goodbye? (original unknown)

Many times I've crossed Nevada in the company of Frank DeCourten and Norma Biggar (hereafter called D & B). Actually I've never met either one, but I know their Roadside Geology of Nevada well. That's where I learned of the state's traumatic history—torn apart, reassembled, buried in ash and welded rock, and now being torn apart again. These stories can be hard to grasp, but I've read and reread the lengthy introduction enough to be awestruck by landscapes that many travelers find dull.

Sturdily bound, with high quality paper—my copy has survived lots of use.

Maps, diagrams and photos are abundant!

In the eight years since D & B published their book, I've often parked off the highway at their suggestion to study and photograph a geologic feature. I think of this as geohopping to geostops, rather than my usual geotripping to geosights (and later blogging about it). Now it's time to give the geostops their due.

One of my favorite stretches of highway between Laramie, Wyoming (home) and the California Central Coast (home of relatives) is US 6 across Nevada. Traffic is light, towns are few, and the geology truly is dramatic!

Geo highlights along US Highway 6, May 2025.

For example, about thirty million years ago, widespread cataclysmic destruction associated with the Great Ignimbrite Flareup (GIF) created Hell right here on Earth. Supervolcanoes erupted repeatedly across today's Nevada depositing ash thousands of feet deep, much of it welded into rock by the searing heat ("ignimbrite" means "fire cloud rock"). Trying to recreate that terrifying Flareup in my mind is one of the joys of driving across Nevada.

But it's impossible to properly imagine the GIF, in part because "no volcanic eruptions ever witnessed by humans come close to rivaling these prehistoric paroxysms." And the geologic record suggests it may be one of the largest ever. Consider this: in Nevada at least 230 supervolcanoes ejected an estimated 17,000 cubic miles of lava! Here's another way to think about it: at least 30 of these eruptions each equaled 600 Mt. St. Helens eruptions!

Blue Jay Maintenance Station on left, remnants of cataclysmic destruction behind.

About 90 miles southwest of Ely, I stopped at Palisade Mesa in the southern Pancake Range. Parking is available at a small rest area next to the Blue Jay Maintenance Station. Volcanic rocks of the GIF are nicely exposed on the steep slope to the east.

Rock pancakes stacked oldest to youngest, from bottom to top.

Palisade Mesa is one of multiple gently-tilted stacks of volcanic rock that give the Pancake Range its name. The escarpment at Blue Jay shows at least four episodes of eruption, all from the immense Central Nevada caldera complex. The pale bottom (oldest) layer is a lightly-welded tuff from an ash flow c. 31 million years ago. Next is a thin black band of glassy vitrophyre—"a flow of glowing ash that became densely welded."

Vitrophyre—beautiful memento of incandescent destruction. James St. John.

The massive brown layer above the vitrophyre is a younger tuff, about 30 million years old. Being a fan of columnar jointing, it was my favorite. The summit is a 2.75 million-year-old tuff that's sufficiently welded to provide an erosion-resistant cap.

I 💖 columnar jointing—created by contraction with cooling.

The view south beckoned.

Palisade Mesa obviously deserved a longer visit, perhaps a hike along the base and up the valley to the south. But not this time. Instead I continued west.

Those who cross the middle of Nevada (e.g. east to west) soon become aware of its extensive deformation even if they have no idea what happened. For example: When I left the Pancake Range I crossed Hot Creek Valley, then the Hot Creek Range, then Stone Cabin Valley, then the Monitor Range, and then Ralston Valley before stopping in Tonopah near the crest of the San Antonio Mountains. This is typical Nevada topography—valleys and mountain ranges one after another, all trending roughly north–south. The great pioneering geologist Clarence Dutton called them “an army of caterpillars marching north from Mexico".

Left of center, caterpillars are marching across the Basin and Range Province (NPS).

The cause of this curious pattern is east-west continental stretching, which started something like 18 million years ago and continues today. Some parts of Nevada and adjacent Utah and California have nearly doubled in width! In the process normal faulting has dropped basins, leaving adjacent land standing high, as mountain ranges.

In Tonopah, I stopped for gas and groceries as I often do. Here Hwy 6 merges with heavily-traveled Hwy 95, but at Coaldale Junction they diverge, and once again I had the highway mostly to myself. This is where I stumbled upon Radio Goldfield several years ago, broadcasting very local news and interesting country-ish, old-timey, new-to-me music. It's still going strong.

At the advice of D & B, I kept an eye out for a diatomite quarry on the left, near the junction with NV Hwy 264. The white patches were obvious. This diatomite is thought to be the same age as late eruptions of the GIF, but the setting was entirely different—a shallow freshwater lake where diatoms (microalgae) basked in the sun. Now they're diatomaceous earth, a soft crumbly rock that's 80–90% silica. Among its many uses are metal polish, toothpaste, cat litter, dynamite, thermal insulation, and bonsai soil amendments.

I would have enjoyed examining the diatomaceous earth, but wasn't clear on ownership.

Diatomaceous earth up close; scanning electron micrograph by Dawid Siodłak.

After continuing west across Montgomery Pass, I dropped into Queen Valley for the final geostop of the day, parking in a large pullout not far from California. Across the valley was the north end of the White Mountains; the snowy Sierra Nevada was visible in the far distance. It was a lovely peaceful place, or so it seemed that day. But nearby were clear signs of geologic trauma.

White Mountains rise steeply above floor of Queen Valley.

Normal faulting evidenced by triangular facets (arrows).

Across the valley at the base of the White Mountains is a normal fault just 3 million years old. This is the Queen Valley fault—a tiny piece of the immense Walker Lane. I had entered a profound but vague tectonic boundary, where the Basin and Range Province meets the great Sierra Nevada.

At Walker Lane (yellow), very different tectonic regions meet. SAFZ is San Andreas Fault Zone, a critical part of this story (Carlson et al. 2013).

Walker Lane is young—just 10 million years old at the south end, and only a few million at the north. The combination of Basin and Range extension and transverse movement of the Sierra Nevada has created a complex zone of faults that's poorly understood. Even so, Walker Lane generates a great deal of excitement among geologists. Perhaps a new plate boundary is forming! Maybe California will drift away!

Like the better known San Andreas Fault to the west, Walker Lane is contributing to the slow, incessant, contrary motions of the Pacific and North American tectonic plates, which are pulling a large part of California northward. Currently the San Andreas is responsible for about 80% of this movement but Walker Lane appears to be catching up.

Fauds & Henry (2008) predict that in another 7 to 8 million years or so, the northern part of the San Andreas will join Walker Lane, extending the Gulf of California north by hundreds of miles and turning California into a peninsula along a new plate boundary. 

If this tectonic shifting continues, as the authors think it will, California will become the island that was regularly reported by explorers hundreds of years ago! This was the "famous cartographic error that appeared on many European maps from the 16th to the 18th centuries" (David Rumsey Map Collection).

"Novissima et accuratissima totius Ameriae" by Nicolaes Visscher, 1690. Large island off the west coast of North America is California. DRMC

Peering even further into the future, we may well find that California Island has become an exotic terrane (quit snickering!). As such, it could travel far and wide before being stopped at some convergent plate boundary, thousands of miles from its origin at Walker Lane.

But Emmie ... our ephemeral lives mislead us. The Earth is far from stable.

Sources

agimark 2018. Splitting North America – The Walker Lane; Part 1 – The Tectonics; Volcano Hotspot blog. Accessed Dec 2025.

Carlson, CW, et al. 2013. Kinematics of the west-central Walker Lane ...  Geosphere 9: 1530–1551.

David Rumsey Map Collection, an unbelievably wonderful resource for fans of old maps. WARNING: it's very easy to spend a lot of time here. https://www.davidrumsey.com/

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

Faulds, JE, and Henry, CD. 2008. Tectonic influences on the spatial and temporal evolution of the Walker Lane: An incipient transform fault along the evolving Pacific – North American plate boundary. Nevada Bureau of Mines and Geology, Arizona Geological Society Digest 22. The future of California is discussed on page 463. PDF

Wolterbeek, M. 2020 (Feb 18). How the burgeoning Walker Lane may split the American West; in Nevada Today, UNV Reno.