Lake Mojave is an ancient

former lake A former is an object, such as a template, Gauge block, gauge or cutting Die (manufacturing), die, which is used to form something such as a boat's Hull (watercraft), hull. Typically, a former gives shape to a structure that may have complex curv ...

fed by the

Mojave River The Mojave River is an intermittent river in the eastern San Bernardino Mountains and the Mojave Desert in San Bernardino County, California, United States. Most of its flow is underground, while its surface channels remain dry most of the time, ...

that, through the

Holocene The Holocene ( ) is the current geological epoch. It began approximately 11,650 cal years Before Present (), after the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene togethe ...

, occupied the

Silver Lake Silver is a chemical element with the Symbol (chemistry), symbol Ag (from the Latin ', derived from the Proto-Indo-European wikt:Reconstruction:Proto-Indo-European/h₂erǵ-, ''h₂erǵ'': "shiny" or "white") and atomic number 47. A soft, whi ...

and

Soda Lake A soda lake or alkaline lake is a lake on the strongly alkaline side of neutrality, typically with a pH value between 9 and 12. They are characterized by high concentrations of carbonate salts, typically sodium carbonate (and related salt complex ...

basins in the

Mojave Desert The Mojave Desert ( ; mov, Hayikwiir Mat'aar; es, Desierto de Mojave) is a desert in the rain shadow of the Sierra Nevada mountains in the Southwestern United States. It is named for the indigenous Mojave people. It is located primarily in ...

San Bernardino County, California San Bernardino County (), officially the County of San Bernardino, is a County (United States), county located in the Southern California, southern portion of the U.S. state of California, and is located within the Inland Empire area. As of the ...

. Its outlet may have ultimately emptied into the

Colorado River The Colorado River ( es, Río Colorado) is one of the principal rivers (along with the Rio Grande) in the Southwestern United States and northern Mexico. The river drains an expansive, arid drainage basin, watershed that encompasses parts of ...

north of

Blythe The name Blythe ( or ) derives from Old English ''bliþe'' ("joyous, kind, cheerful, pleasant"; modern ''blithe''), and further back from Proto-Germanic ''*blithiz'' ("gentle, kind"). People * Blythe (given name), including a list of people named ...

Geography

Lake Mojave existed in

San Bernardino County San Bernardino County (), officially the County of San Bernardino, is a county located in the southern portion of the U.S. state of California, and is located within the Inland Empire area. As of the 2020 U.S. Census, the population was 2,181, ...

. The city of

Las Vegas Las Vegas (; Spanish for "The Meadows"), often known simply as Vegas, is the 25th-most populous city in the United States, the most populous city in the state of Nevada, and the county seat of Clark County. The city anchors the Las Vegas ...

lies northeast of Lake Mojave. On the western side, Lake Mojave was bordered by mountains that steeply rise from the basin. The eastern side is more gentle, featuring

alluvial fan An alluvial fan is an accumulation of sediments that fans outwards from a concentrated source of sediments, such as a narrow canyon emerging from an escarpment. They are characteristic of mountainous terrain in arid to semiarid climates, but a ...

s and pediment.

The lake

At its maximum stand, Lake Mojave had a surface area of and a volume of . Lake Mojave had two separate lake level stands, the A stand and the B stand. The A stand lies at an altitude of above sea level and the B stand at an altitude of . The lake was about deep. 15

s abut the shores of Lake Mojave that face the Soda Mountains. A present-day bay exists on the northwestern side of the Silver Lake basin and includes wavecut terraces and a beach ridge.

and

exist today where Lake Mojave formerly existed. Soda Lake slopes to the north and lies at a higher altitude than Silver Lake, thus water tends to fill Silver Lake first. Beach ridges and

shoreline A shore or a shoreline is the fringe of land at the edge of a large body of water, such as an ocean, sea, or lake. In physical oceanography, a shore is the wider fringe that is geologically modified by the action of the body of water past a ...

s testify to the existence of a past lake in the Silver Lake basin. One major beach ridge complex is named the El Capitan Beach Ridge complex and contains

gravel Gravel is a loose aggregation of rock fragments. Gravel occurs naturally throughout the world as a result of sedimentary and erosive geologic processes; it is also produced in large quantities commercially as crushed stone. Gravel is classifi ...

and

sand Sand is a granular material composed of finely divided mineral particles. Sand has various compositions but is defined by its grain size. Sand grains are smaller than gravel and coarser than silt. Sand can also refer to a textural class of s ...

. Sediments from Lake Mojave and its two successor basins may be part of the sources of sand for the

Kelso Dunes Kelso Dunes, also known as the Kelso Dune Field, is the largest field of Aeolian processes, aeolian sand deposits in the Mojave Desert. The region is protected by the Mojave National Preserve and is located near the town of Baker, California, B ...

. Dating of dune deposition suggests that the deposition events often correspond to times where water levels in Lake Mojave were less stable.

Hydrology

Inflow

The

is the principal river reaching the Lake Mojave basin. Most water of the Mojave River ultimately comes from the

San Bernardino Mountains The San Bernardino Mountains are a high and rugged mountain range in Southern California in the United States. Situated north and northeast of San Bernardino and spanning two California counties, the range tops out at at San Gorgonio Mountain � ...

, southwest. Precipitation increased in response to southward shifts of the

polar jet stream Jet streams are fast flowing, narrow, meandering air currents in the atmospheres of some planets, including Earth. On Earth, the main jet streams are located near the altitude of the tropopause and are westerly winds (flowing west to east) ...

; this and floods probably contributed to the formation of Lake Mojave. The Mojave River flows into the

since about 2–1.5 million years ago, when its previous southward course was blocked by the uplift of the

Transverse Ranges The Transverse Ranges are a group of mountain ranges of southern California, in the Pacific Coast Ranges physiographic region in North America. The Transverse Ranges begin at the southern end of the California Coast Ranges and lie within Santa B ...

. The Mojave River did not always end in Lake Mojave; at other points of its history it reached Lake Harper,

Lake Manix Lake Manix is a former lake fed by the Mojave River in the Mojave Desert. It lies within San Bernardino County, California. Located close to Barstow, this lake had the shape of a cloverleaf and covered four basins named Coyote, Cady/Manix, Troy an ...

, the Cronese Lakes and

Lake Manly Lake Manly was a pluvial lake in Death Valley, California, covering much of Death Valley with a surface area of during the so-called "Blackwelder stand". Water levels varied through its history, and the chronology is further complicated by act ...

. Lake Mojave was reached about 20,000 years before present by water overflowing from Lake Manix. Compared to today, water flow would have to be at least ten times higher to allow for the formation of Lake Mojave.

Outflow

A bedrocklined channel extends from a bay on the northern side of Silver Lake and forms the outlet of Lake Mojave. It is at times less than wide. The channel terminates into Dry Lake playa, away. This spillway stabilized the levels of Lake Mojave during the late

Pleistocene The Pleistocene ( , often referred to as the ''Ice age'') is the geological Epoch (geology), epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fina ...

. It was once thought that overflow from Lake Mojave was nourishing a freshwater

Lake Dumont A lake is an area filled with water, localized in a basin, surrounded by land, and distinct from any river or other outlet that serves to feed or drain the lake. Lakes lie on land and are not part of the ocean, although, like the much larger ...

, but later

ostracod Ostracods, or ostracodes, are a class of the Crustacea (class Ostracoda), sometimes known as seed shrimp. Some 70,000 species (only 13,000 of which are extant) have been identified, grouped into several orders. They are small crustaceans, typic ...

research indicated that that area was

groundwater Groundwater is the water present beneath Earth's surface in rock and soil pore spaces and in the fractures of rock formations. About 30 percent of all readily available freshwater in the world is groundwater. A unit of rock or an unconsolidate ...

-supported

wetland A wetland is a distinct ecosystem that is flooded or saturated by water, either permanently (for years or decades) or seasonally (for weeks or months). Flooding results in oxygen-free (anoxic) processes prevailing, especially in the soils. The ...

. Water from Lake Mojave eventually reached the Amargosa River and

Death Valley Death Valley is a desert valley in Eastern California, in the northern Mojave Desert, bordering the Great Basin Desert. During summer, it is the Highest temperature recorded on Earth, hottest place on Earth. Death Valley's Badwater Basin is the ...

. In 1916-1917 the outlet channel was deepened in order to lower water levels. Before that, the floor of the channel had an elevation of .

Climate

Present day climate in the area is hot and dry. On average, summer temperatures exceed . Average precipitation is about . Most of it falls during winter and early spring, with about one quarter coming during summer from the

Gulf of California The Gulf of California ( es, Golfo de California), also known as the Sea of Cortés (''Mar de Cortés'') or Sea of Cortez, or less commonly as the Vermilion Sea (''Mar Bermejo''), is a marginal sea of the Pacific Ocean that separates the Baja Ca ...

and

Gulf of Mexico The Gulf of Mexico ( es, Golfo de México) is an oceanic basin, ocean basin and a marginal sea of the Atlantic Ocean, largely surrounded by the North American continent. It is bounded on the northeast, north and northwest by the Gulf Coast of ...

. This low precipitation contrasts to a high evaporation rate of .

Biology

A number of shells of '' Anodonta californiensis'' have been found at Lake Mojave. '' Phacotus'' freshwater algae developed in early Holocene lake stages.

Ostracod Ostracods, or ostracodes, are a class of the Crustacea (class Ostracoda), sometimes known as seed shrimp. Some 70,000 species (only 13,000 of which are extant) have been identified, grouped into several orders. They are small crustaceans, typic ...

s of Lake Mojave include '' Limnocythere bradburyi'' and '' Limnocythere ceriotuberosa''. Lake Mojave was surrounded by a mix of pinyon-juniper and

Joshua tree ''Yucca brevifolia'' is a plant species belonging to the genus ''Yucca''. It is tree-like in habit, which is reflected in its common names: Joshua tree, yucca palm, tree yucca, and palm tree yucca. This monocotyledonous tree is native to the ar ...

woodlands down to altitudes of and desert vegetation. Present-day vegetation in the area includes

creosote bush ''Larrea tridentata'', called creosote bush and greasewood as a plant, chaparral as a medicinal herb, and ''gobernadora'' (Spanish for "governess") in Mexico, due to its ability to secure more water by inhibiting the growth of nearby plants. In S ...

saltbush Saltbush is a vernacular plant name that most often refers to '' Atriplex'', a genus of about 250 plants distributed worldwide from subtropical to subarctic regions. ''Atriplex'' species are native to Australia, North and South America, and Eurasia. ...

and ''

Opuntia ''Opuntia'', commonly called prickly pear or pear cactus, is a genus of flowering plants in the cactus family Cactaceae. Prickly pears are also known as ''tuna'' (fruit), ''sabra'', ''nopal'' (paddle, plural ''nopales'') from the Nahuatl word f ...

''. There is more vegetation in washes and on river terraces.

Chronology

Lake Mojave existed between 22,000 and 9,000 years

before present Before Present (BP) years, or "years before present", is a time scale used mainly in archaeology, geology and other scientific disciplines to specify when events occurred relative to the origin of practical radiocarbon dating in the 1950s. Becaus ...

. Based on the Wells chronology, the lake filled before 27,000 years before present and from then on fluctuated below the A-shoreline. The lake was stable at the A-shoreline 21,900 - 19,750 and 16,850 - 13,850 years before present. The early phase is also known as Lake Mojave I, while later phases are also known as Lake Mojave II. Alternative age ranges are 20,900 - 19,600 for Lake Mojave I and 16,500 - 13,400 for Lake Mojave II. Water draining from

after the formation of Afton Canyon may have aided in the development of Lake Mojave, although much of the water would have continued into

due to the insufficient volume of the Lake Mojave basin. Between 13,600 and 11,500 years before present, the formation of a

spillway A spillway is a structure used to provide the controlled release of water downstream from a dam or levee, typically into the riverbed of the dammed river itself. In the United Kingdom, they may be known as overflow channels. Spillways ensure tha ...

caused Lake Mojave to abandon its A-shoreline and drop to the B-shoreline. Lake Mojave stabilized at the B-shoreline until 8,700 years before present. Other estimates assume a drying about 9,700 years before present. The disappearance of Lake Mojave was caused by climatic changes at the start of the

. Wind erosion affected the beach and

delta Delta commonly refers to: * Delta (letter) (Δ or δ), a letter of the Greek alphabet * River delta, at a river mouth * D ( NATO phonetic alphabet: "Delta") * Delta Air Lines, US * Delta variant of SARS-CoV-2 that causes COVID-19 Delta may also ...

deposits left by Lake Mojave, forming aeolian sediments. Presently, only rarely do lakes form in the basin of Lake Mojave. Individual occurrences occurred in 1916–1917, 1938-1939 and 1969; this latter lake stage was photographed and it submerged the

Tonopah and Tidewater railroad The Tonopah and Tidewater Railroad was a former class II railroad that served eastern California and southwestern Nevada. The railroad was built mainly to haul borax from Francis Marion Smith's Pacific Coast Borax Company mines located just eas ...

. Other infillings occurred 3,910 ± 152 and 470 ± 160 years ago. Such resurgences of the lake depend on anomalously high precipitation on the San Bernardino Mountains, and are climatically linked to the Little Ice Age and other glacial expansion episodes. The existence of such lakes was not only limited by climate factors but also by a generally shallow lake basin that caused a strong increase in evaporation with only slight increases in water levels.

Archaeology

A steady food and freshwater supply as well as the presence of rocks that could be used to manufacture tools drew early humans towards Lake Mojave. As lake levels dropped, people migrated progressively farther down to reach the lake. Some presumably archaeological sites have been found at Lake Mojave, including alignments of

basalt Basalt (; ) is an aphanite, aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the planetary surface, surface of a terrestrial ...

boulders.

Biface A hand axe (or handaxe or Acheulean hand axe) is a Prehistory, prehistoric stone tool with two faces that is the longest-used tool in human history, yet there is no academic consensus on what they were used for. It is made from stone, usually f ...

s and

projectile A projectile is an object that is propelled by the application of an external force and then moves freely under the influence of gravity and air resistance. Although any objects in motion through space are projectiles, they are commonly found in ...

s have been found on its shores, the latter are dated about 10,000 - 8,000 years before present, these archaeological findings are known as the "Lake Mojave" complex. The so-called "Lake Mojave complex" is a cultural system that was active between 9,000 and 6,000 BC. Possibly, such cultures were derived from the

Clovis culture The Clovis culture is a prehistoric Paleoamerican culture, named for distinct stone and bone tools found in close association with Pleistocene fauna, particularly two mammoths, at Blackwater Locality No. 1 near Clovis, New Mexico, in 1936 ...

and formed when big mammals disappeared and early humans had to search for different sources of food.

References

Sources

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