Lake Bonneville was the largest Late Pleistocene paleolake in the Great Basin of western North America. It was a pluvial lake that formed in response to an increase in precipitation and a decrease in evaporation as a result of cooler temperatures. The lake covered much of what is now western Utah and at its highest level extended into present-day Idaho and Nevada. Many other hydrographically closed basins in the Great Basin contained expanded lakes during the Late Pleistocene, including Lake Lahontan in northwestern Nevada.
Geologic description
Shorelines of Lake Bonneville are visible above Salt Lake City along the western front of the Wasatch Mountains and on other mountains throughout the Bonneville basin.Gilbert, G.K., 1890. Lake Bonneville. U.S. Geological Survey Monograph 1. 438 pp. These shorelines appear as shelves or benches that protrude from the mountainside above the valley floor, are visible on the ground from long distances and on satellite images, and have both depositional and erosional segments along their lengths.Chen, C.Y. and Maloof, A.C., 2017. Revisiting the deformed high shoreline of Lake Bonneville. Quaternary Science Reviews 159, p. 169–189. Three shorelines of Lake Bonneville that can be traced throughout the basin have been given names: Stansbury, Bonneville, and Provo. The Stansbury and Bonneville shorelines formed during the transgressive phase of Lake Bonneville; the Provo shoreline formed during the overflowing phase.Oviatt, C.G., 2015. Chronology of Lake Bonneville, 30,000 to 10,000 yr B.P. Quaternary Science Reviews 110, 166–171. Numerous other unnamed shorelines, which cannot be mapped everywhere in the basin, some of which formed during the transgressive phase and some during the regressive phase, are also present on piedmont slopes and alluvial fans. At its maximum, when Lake Bonneville was more than deep and almost in surface area,Mifflin, M.D. and Wheat, M.M., 1979. Pluvial lakes and estimated pluvial climates of Nevada. Nevada Bureau of Mines and Geology Bulletin 94. Mackay School of Mines, University of Nevada, Reno, NV. 57 pp. it covered almost as much area as modern Lake Michigan, although its shoreline was more complex with many islands and peninsulas. Great Salt Lake, Utah Lake, and Sevier Lake are the largest post-Bonneville lakes in the Bonneville basin.
Causes of lake expansion and contraction Lake Bonneville was not a proglacial lake although it formed between about 30,000 and 13,000 years ago, when glaciers at many places on Earth were expanded relative to today during the last major glaciation.Scott, W.E., McCoy, W.D., Shroba, R.R., Rubin, M., 1983. Reinterpretation of the exposed record of the last two cycles of Lake Bonneville, western United States. Quaternary Research 20, 261–285. For most of its existence (that is, during the transgressive plus regressive phases) Lake Bonneville had no river outlet and occupied a hydrographically closed basin. Changes in lake level were the result of changes in water balance caused by climate change (a simplified version of the water-balance equation is inputs equal outputs plus-or-minus storage changes).Street-Perrott, E.A., Harrison, S.P., 1985. Lake levels and climate reconstruction. In: Hecht, A.D., ed. Paleoclimate Analysis and Modeling. Wiley, New York. Storage changes are equal to volume changes, and changes in volume are correlated with changes in lake level. When inputs (e.g., precipitation; runoff in rivers) were greater than outputs (e.g., evaporation from the lake surface; evapotranspiration in the basin), lake level rose, and when outputs were greater than inputs, lake level fell.Ibarra, D.E., Oster, J.L., Winnick, M.J., Caves Rugenstein, J.K., Byrne, M.P., and Chamberlain, C.P., 2019. Lake area constraints on past hydroclimate in the western United States: Application to Pleistocene Lake Bonneville. Lund, W.R., McKean, A.P., and Bowman, S.D., eds., in press, Proceedings Volume: 2018 Lake Bonneville Geologic Conference and Short Course, Utah Geological Survey; McGee, D., Moreno-Chamarro, E., Marshall, J., and Galbraith. E.D., 2018. Western U.S. lake expansions during Heinrich stadials linked to Pacific Hadley circulation. Science Advances volume 4, issue 11, 10 p. [https://www.science.org/toc/sciadv/4/11 ]; Putnam, A.E., 2015. A glacial zephyr. Nature Geoscience 8, 175–176; Putnam, A.E., 2015. A glacial zephyr. Nature Geoscience 8, 175–176. Changes in global atmospheric circulation led to changes in the water budget of Lake Bonneville and other lakes in the Great Basin of western North America.Antevs, E., 1948. The Great Basin, with emphasis on glacial and post-glacial times – Climatic changes and pre-white man. Bulletin of the University of Utah Biological Series 38, 168-191.Morrill, C., Lowry, D.P., and Hoell, A., 2018. Thermodynamic and dynamic causes of pluvial conditions during the Last Glacial Maximum in western North America. Geophysical Research Letters 45(1), p. 335-345. Mountain glaciers in the Bonneville drainage basin stored less than 5% of the water that Lake Bonneville held at its maximumLaabs, B.J.C. and J.S. Munroe, J.S., 2016. Late Pleistocene mountain glaciation in the Lake Bonneville basin. in Oviatt, C.G. and Shroder, J.F., Jr., eds., Lake Bonneville: A scientific update. Developments in Earth Surface Processes 20. Elsevier. p. 462-503. and so even if all of the mountain glaciers in the basin melted at once and the water flowed into the lake (that did not happen since it took thousands of years for the mountain glaciers to melt, and Lake Bonneville was falling by that time), it would have had little effect on lake level. Lake Bonneville had no river connection with the huge North American ice sheets. While Lake Bonneville existed, the patterns of wave- and current-forming winds were not significantly affected by the Laurentide and Cordilleran ice sheets in northern North America.Jewell, P.W., 2010. River incision, circulation, and wind regime of Pleistocene Lake Bonneville, USA. Palaeogeography, Palaeoclimatology, Palaeoecology 293, 41-50.
The name "Bonneville" and its discovery Lake Bonneville was named by the geologist G.K. Gilbert after Benjamin Louis Eulalie de Bonneville (1796–1878), a French-born officer in the United States Army who was also a fur trapper and explorer in the American West. Bonneville's adventures were popularized by Washington Irving in the 1800s,Irving, W., 1868. Adventures of Captain Bonneville. in The works of Washington Irving, Volume six. The New Hudson Edition. P.F. Collier & Son, New York. p. 21-524. but Captain Bonneville probably never saw Great Salt Lake or the Great Basin.Miller, D.E., 1966. Great Salt Lake: A historical sketch. in Stokes, W.L., ed., Guidebook to the Geology of Utah: The Great Salt Lake. Utah Geological Society, p. 3-24. G.K. Gilbert was one of the greatest geologists of the 19th Century, and his monumental work on Lake Bonneville, published in 1890, set the stage for scientific research on the paleolake that continues today.Oviatt, C.G. and Shroder, J.F., Jr., Eds., 2016. Lake Bonneville: A scientific update. Developments in Earth Surface Processes 20. Elsevier. 659 p. Gilbert was the first person to describe the major features of Lake Bonneville, however, many other early European and American explorers in the region recognized the shorelines of the ancient lake, such as Captain John C. Frémont in 1843 and even earlier by Father Silvestre Velez de Escalante in 1776. Escalante, in a journal entry after visiting what would be named Utah Lake wrote, "This place, which we named Llano Salado, because we found some thin white shells there, seems to have once had a much larger lake than the present one." Although a general description and understanding of Lake Bonneville has been established by the work of many people, details of the paleolake, including its history and connections to global environmental systems, will be pursued for many years to come.
Geologic history Lake Bonneville began to rise from elevations similar to those of modern Great Salt Lake about 30,000 years ago.Oviatt, C.G. and Pedone, V.A., 2024, online. Chronology of the early transgressive phase of Lake Bonneville. Quaternary Research, Published online by Cambridge University Press 04 April 2024, doi:10.1017/qua.2024.10. During its early transgressive phase the lake fluctuated within a few 10s of meters of the level of modern Great Salt Lake, but after about 24,000 years ago it began a rapid rise to higher elevations, reaching its highest elevation (the Bonneville shoreline) about 17,500 years ago.Oviatt C.G., 2020, G.K. Gilbert and the Bonneville shoreline: Geology of the Intermountain West, v. 7, p. 300-320, doi: 10.31711/giw.v7.pp300-320. During its transgressive phase in the closed basin (an endorheic basin), lake level oscillated because of changes in climate.Nelson, D.T. and Jewell, P.W., 2015. Transgressive stratigraphic record and possible oscillations of Late Pleistocene Lake Bonneville, northern Hogup Mountains, Utah, U.S.A. Palaeogeography, Palaeoclimatology, Palaeoecology 432, 58-67. At its highest level the lake had risen to the lowest point on its basin rim and had begun to overflow into the Snake River drainage basin near Red Rock Pass in what is now southeastern Idaho.O’Connor, J., 1993. Hydrology, Hydraulics, and Geomorphology of the Bonneville Flood. Geological Society of America Special Paper 274. 83 p.; O’Connor, J., 2016. The Bonneville flood — A veritable débâcle. in Oviatt, C.G. and Shroder, J.F., Jr., eds., Lake Bonneville: A scientific update. Developments in Earth Surface Processes 20. Elsevier. p. 105-126; Malde, H.E., 1968. The catastrophic Late Pleistocene Bonneville flood in the Snake River Plain, Idaho. U.S. Geological Survey Professional Paper 596, 52 p.Shroder, J.F., Cornwell, K., Oviatt, C.G., Lowndes, T.C., 2016. Chapter 4. Landslides, Alluvial Fans, and Dam Failure at Red Rock Pass: The Outlet of Lake Bonneville. in Oviatt, C.G., Shroder, J.F., Jr., Eds., Lake Bonneville: A scientific update. Developments in Earth Surface Processes 20. Elsevier. p. 75-87. The overflow, which would have begun as a trickle across the dam formed by the Marsh Creek alluvial fan, quickly evolved into a tremendous flood, the Bonneville flood, which charged down the Marsh Creek valley to the Portneuf River, into the Snake River and then into the Columbia River and Pacific Ocean. Groundwater sapping on the north slope of the Marsh Creek alluvial fan, which began long before the lake had reached its highest level, added to the instability and ultimate collapse of the fan-dam.