Nearly as large as Lake Michigan, the Ice Age lake spread across much of western Utah and parts of Nevada and Idaho.
When it eventually receded, it left behind flat, brightplayasand salt flats rich with minerals—a landscape that would later serve as the setting for feats of engineering and technological ingenuity, as well as epic tales of exploration and desperation.
Lake Bonneville began forming about 55,000 years ago during a cool, wet period, when volcanic eruptions in what’s now southeastern Idahodiverted the Bear River, causing water to gather in Gem Valley and other basins to the south.
For tens of thousands of years, a natural dam atRed Rock Passhelped confine the lake.
Then, about 18,000 years ago, water breached that dam, unleashing a torrent that entered the Columbia River system.
Over a six-week period, amid one of North America’slargest floods, lake levels plummeted by more than 350 feet.
As the climate warmed and dried in subsequent millennia, the lake shrank dramatically, leaving remnants that include today’s Great Salt Lake, Utah Lake, and Sevier Lake.
Lake Bonneville may be gone, but its imprint on the region’s landscape remains—even in satellite imagery.
In this image captured by theOLI on the NASA-USGSLandsat 8satellite, bathtub-like rings and wave-cut terraces trace the position of former shorelines.
The dried lakebed—where fine-grained clay, marl, and sandysedimentsettled out of the water—appears pale in comparison to the darker, rockier, more vegetated surroundings.
In deep parts of the basin, where runoff and groundwater still pool, bright deposits ofevaporite mineralscoat the land surfaces, formingsalt flats.
These remarkably flat surfaces are the product of water gradually evaporating and concentrating minerals to produce brines and hard mineral crusts, typically including halite and gypsum, along with potassium- and magnesium-bearing salts.
Brines and deposits like these—particularly ofpotash, which is used as a fertilizer—have long made the playa a target for mining, as seen in the rectangular evaporation ponds above and below.
In contrast, the darker, more rugged terrain—including the Silver Island Mountains, the Newfoundland Mountains, and the Pilot Range—that rises above the playas is built from layers of erosion-resistantsedimentaryandmetasedimentarybedrock that is hundreds of millions of years old.
These mountains also contain younger igneous andmetamorphicrocks that formed when magma intruded into the ancient sedimentary sequence.
Crater Island, for instance, is composed of sedimentary rocks, including silica-rich sandstones and quartzites that formed as sands accumulated in a shallow ocean, as well as intrusions of quartz monzonite, granites, and otherigneousrocks.
Periods of crustal stretching later produced thefault-block mountainsthat define the landscape.
Mapping geological distinctions like this took center stage in June 2026 when NASA scientists and engineers working with the agency’sDAVINCI missioncame to Crater Island—a place they call “Venus on Earth”—tofield-testthe design of a set of cameras and a package of instruments that will eventually descend through the thick atmosphere of Venus and photograph mountains at scales finer than these Landsat images.
During a 60-minute descent, thepioneering probewill capture near-infrared images, measure the atmospheric chemistry, and explore the environment of a world in unprecedented detail.
During the rehearsals at Crater Island, the camera system took hundreds of images of various rock formations, including iron-rich and silica-rich rock units, while suspended from a helicopter as it descended toward the surface.
Using only the images acquired by DAVINCI’s camera systems, the team made three-dimensional maps of the area consistent with existinggeologic maps, giving the scientists confidence that they will be able to map the geology of an analogous mountainous region on Venus that DAVINCI will study, an area called Alpha Regio.
Other epic adventures have played out on and around Lake Bonneville’s playas, as well.
The flat, smooth surfaces have often been the setting for new land speed records.
In 1960, Mickey Thompsonbecame the first American to break the 400-miles-per-hour barrier, hitting406.60 miles per hour in astreamlined race caron the Bonneville Salt Flats.
The feat temporarily earned him the nickname“fastest man on Earth.”
More recently, in August 2026, Andy Green, the first person to break the sound barrier on land, set a recordfor the fastest land speed in a hydrogen-fueled internal-combustion vehicle, reaching 406.320 miles per hour.
By burning hydrogen rather than gasoline, the“rocket car”produced no carbon dioxide.
Nearly two centuries earlier, in August 1846, members of the ill-fated Donner-Reed Partyalso passed along the southern edge of Crater Island.
As part of a shortcut toward Pilot Peak, they journeyed from Hastings Pass, past Floating Island, and toward Donner Spring.
However, in an ominous sign of challenges to come, their heavy wagons broke through the thin salt crust and became mired in underlying mud, slowing them down and prompting them toabandonseveral wagons in the desert.
NASA Earth Observatory images by Michala Garrison, using Landsat data from theU.S. Geological Survey. Story by Adam Voiland.
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The Center for Land Use Interpretation, Intrepid Potash Wendover. Accessed August 21, 2026.
Garvin, J.B.,et al.Revealing the Mysteries of Venus: The DAVINCI Mission.The Planetary Science Journal,3.
Hill Air Force BaseTraces of Travel: Donner-Reed Wagon Sites on the Hastings Cutoff. Accessed August 21, 2026.
Idaho State University, Lake Bonneville Flood. Accessed August 21, 2026.
NASAUtah Helicopter Flights Test NASA’s DAVINCI Mission to Venus. Accessed August 21, 2026.
NASA,DAVINCI. Accessed August 21, 2026.
NASA Earth ObservatoryBonneville Salt Flats. Accessed August 21, 2026.
National Park Service, Donner and Reed Wagon Train Incident. Accessed August 21, 2026.
Utah Geological Survey, Lake Bonneville. Accessed August 21, 2026
Utah Geological Survey, Geologic History. Accessed August 21, 2026.
Utah Geological Survey, Great Salt Lake and Lake Bonneville. Accessed August 21, 2026.
Utah Department of Natural ResourcesGeologic Map of the Lucin 4 SW Quadrangle. Accessed August 21, 2026.
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