A pluvial lake is a body of water that accumulated in a basin because of a greater moisture availability resulting from changes in temperature and/or precipitation. These intervals of greater moisture availability are not always contemporaneous with glacial periods. Pluvial lakes are typically closed lakes that occupied endorheic basins. Pluvial lakes that have since evaporated and dried out may also be referred to as paleolakes. [1]
The word comes from the Latin pluvia, which means "rain". [2]
Pluvial lakes represent changes in the hydrological cycle: wet cycles generate large lakes, and dry cycles cause the lakes to recede. Accumulated sediments show the variation in water level. During glacial periods, when the lake level is fairly high, mud sediments will settle out and be deposited. At times in between glaciers (interglacial), salt deposits may be present because of the arid climate and the evaporation of lakewater. [3]
Several pluvial lakes formed in what is now the southwestern United States during the glaciation of the late Pleistocene. One of these was Lake Bonneville in western Utah, which covered roughly 19,000 square miles (49,000 km2). When Lake Bonneville was at its maximum water level, it was 1,000 feet (300 m) higher than the Great Salt Lake.
Fresh water mollusks have been found in mud deposits from Searles Lake in California and suggest that the water temperature was about 7 degrees Fahrenheit (or 4 degrees Celsius) cooler than current temperatures. Radiocarbon dating of the youngest mud beds yield dates from 24,000 to 12,000 years ago. [3]
When warm air from arid regions meets chilled air from glaciers, cloudy, cool, rainy weather is created beyond the terminus of the glacier. That humid climate was present during the last glacial period in North America and caused more precipitation than evaporation. The increase in rainfall fills the drainage basin and forms a lake. [4]
During interglacial periods, the climate becomes arid once more and causes the lakes to evaporate and dry up. [5]
A glacier is a persistent body of dense ice that is constantly moving under its own weight. A glacier forms where the accumulation of snow exceeds its ablation over many years, often centuries. It acquires distinguishing features, such as crevasses and seracs, as it slowly flows and deforms under stresses induced by its weight. As it moves, it abrades rock and debris from its substrate to create landforms such as cirques, moraines, or fjords. Although a glacier may flow into a body of water, it forms only on land and is distinct from the much thinner sea ice and lake ice that form on the surface of bodies of water.
An ice age is a long period of reduction in the temperature of Earth's surface and atmosphere, resulting in the presence or expansion of continental and polar ice sheets and alpine glaciers. Earth's climate alternates between ice ages and greenhouse periods, during which there are no glaciers on the planet. Earth is in the Quaternary glaciation. Individual pulses of cold climate within an ice age are termed glacial periods, and intermittent warm periods within an ice age are called interglacials or interstadials.
The Pleistocene is the geological epoch that lasted from c. 2.58 million to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was finally confirmed in 2009 by the International Union of Geological Sciences, the cutoff of the Pleistocene and the preceding Pliocene was regarded as being 1.806 million years Before Present (BP). Publications from earlier years may use either definition of the period. The end of the Pleistocene corresponds with the end of the last glacial period and also with the end of the Paleolithic age used in archaeology. The name is a combination of Ancient Greek πλεῖστος (pleîstos), meaning "most", and καινός, meaning "new".
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.
An endorheic basin is a drainage basin that normally retains water and allows no outflow to other external bodies of water, such as rivers or oceans, where drainage converges instead into lakes or swamps, permanent or seasonal, that equilibrate through evaporation. They are also called closed or terminal basins, internal drainage systems, or simply basins. Endorheic regions contrast with exorheic regions, where surface waters eventually drain into the ocean. Endorheic water bodies include some of the largest lakes in the world, such as the Caspian Sea, the world's largest inland body of water.
The geography of Tibet consists of the high mountains, lakes and rivers lying between Central, East and South Asia. Traditionally, Western sources have regarded Tibet as being in Central Asia, though today's maps show a trend toward considering all of modern China, including Tibet, to be part of East Asia. Tibet is often called "the roof of the world," comprising tablelands averaging over 4,950 metres above the sea with peaks at 6,000 to 7,500 m, including Mount Everest, on the border with Nepal.
The Great Basin Desert is part of the Great Basin between the Sierra Nevada and the Wasatch Range. The desert is a geographical region that largely overlaps the Great Basin shrub steppe defined by the World Wildlife Fund, and the Central Basin and Range ecoregion defined by the U.S. Environmental Protection Agency and United States Geological Survey. It is a temperate desert with hot, dry summers and snowy winters. The desert spans large portions of Nevada and Utah, and extends into eastern California. The desert is one of the four biologically defined deserts in North America, in addition to the Mojave, Sonoran, and Chihuahuan Deserts.
Natural salt pans or salt flats are flat expanses of ground covered with salt and other minerals, usually shining white under the sun. They are found in deserts and are natural formations.
Tollmann's bolide hypothesis is a hypothesis presented by Austrian palaeontologist Edith Kristan-Tollmann and geologist Alexander Tollmann in 1994. The hypothesis postulates that one or several bolides struck the Earth around 7640 ± 200 years BCe, with a much smaller one approximately 3150 ± 200 BCE. The hypothesis tries to explain early Holocene extinctions and possibly legends of the Universal Deluge.
Aeolian processes, also spelled eolian, pertain to wind activity in the study of geology and weather and specifically to the wind's ability to shape the surface of the Earth. Winds may erode, transport, and deposit materials and are effective agents in regions with sparse vegetation, a lack of soil moisture and a large supply of unconsolidated sediments. Although water is a much more powerful eroding force than wind, aeolian processes are important in arid environments such as deserts.
The Great Salt Lake Desert is a large dry lake in northern Utah, United States, between the Great Salt Lake and the Nevada border. It is a subregion of the larger Great Basin Desert, and noted for white evaporite Lake Bonneville salt deposits including the Bonneville Salt Flats.
The Quaternary glaciation, also known as the Pleistocene glaciation, is an alternating series of glacial and interglacial periods during the Quaternary period that began 2.58 Ma and is ongoing. Although geologists describe this entire period up to the present as an "ice age", in popular culture this term usually refers to the most recent glacial period, or to the Pleistocene epoch in general. Since Earth still has polar ice sheets, geologists consider the Quaternary glaciation to be ongoing, though currently in an interglacial period.
A lacustrine plain or lake plain is a plain formed due to the past existence of a lake and its accompanying sediment accumulation. Lacustrine plains can be formed through one of three major mechanisms: glacial drainage, differential uplift, and inland lake creation and drainage. Lake plains can have various uses depending on where and how they form.
A sabkha is a coastal, supratidal mudflat or sandflat in which evaporite-saline minerals accumulate as the result of semiarid to arid climate. Sabkhas are gradational between land and intertidal zone within restricted coastal plains just above normal high-tide level. Within a sabkha, evaporite-saline minerals sediments typically accumulate below the surface of mudflats or sandflats. Evaporite-saline minerals, tidal-flood, and aeolian deposits characterize many sabkhas found along modern coastlines. The accepted type locality for a sabkha is at the southern coast of the Persian Gulf, in the United Arab Emirates. Sabkha is a phonetic transliteration of the Arabic word used to describe any form of salt flat. A sabkha is also known as a sabkhah,sebkha, or coastal sabkha.
The Sahara pump theory is a hypothesis that explains how flora and fauna migrated between Eurasia and Africa via a land bridge in the Levant region. It posits that extended periods of abundant rainfall lasting many thousands of years in Africa are associated with a "wet-green Sahara" phase, during which larger lakes and more rivers existed. This caused changes in the flora and fauna found in the area. Migration along the river corridor was halted when, during a desert phase 1.8–0.8 million years ago (mya), the Nile ceased to flow completely and possibly flowed only temporarily in other periods due to the geologic uplift of the Nile River region.
A desert is a barren area of landscape where little precipitation occurs and, consequently, living conditions are hostile for plant and animal life. The lack of vegetation exposes the unprotected surface of the ground to denudation. About one-third of the land surface of the Earth is arid or semi-arid. This includes much of the polar regions, where little precipitation occurs, and which are sometimes called polar deserts or "cold deserts". Deserts can be classified by the amount of precipitation that falls, by the temperature that prevails, by the causes of desertification or by their geographical location.
Zhuye Lake is the terminal lake of the Shiyang River, which is located in the east of the Hexi Corridor in Gansu Province, China. Zhuye Lake is located in the marginal area of the Asian monsoon and is affected by both the Asian monsoon system and the Westerly jet. By understanding the Holocene record in Zhuye Lake, the interaction of different climate systems during the Holocene can be studied. At the same time, the Asian monsoon system is climatically dynamic; changes in its sphere of influence can result in severe drought or flood over large, densely populated, regions. In addition, Zhuye Lake and the surrounding area in arid NW China are in ecological imbalance – a consequence of human impacts and climate. Understanding the environmental history here can assist climatological forecasting of the Asian monsoon system and ecosystem reconstruction.
Lake Tauca is a former lake in the Altiplano of Bolivia. It is also known as Lake Pocoyu for its constituent lakes: Lake Poopó, Salar de Coipasa and Salar de Uyuni. The lake covered large parts of the southern Altiplano between the Eastern Cordillera and the Western Cordillera, covering an estimated 48,000 to 80,000 square kilometres of the basins of present-day Lake Poopó and the Salars of Uyuni, Coipasa and adjacent basins. Water levels varied, possibly reaching 3,800 metres (12,500 ft) in altitude. The lake was saline. The lake received water from Lake Titicaca, but whether this contributed most of Tauca's water or only a small amount is controversial; the quantity was sufficient to influence the local climate and depress the underlying terrain with its weight. Diatoms, plants and animals developed in the lake, sometimes forming reef knolls.
Lake Estancia was a lake formed in the Estancia Valley, central New Mexico, which left various coastal landforms in the valley. The lake was mostly fed by creek and groundwater from the Manzano Mountains, and fluctuated between freshwater stages and saltier stages. The lake had a diverse fauna, including cutthroat trout; they may have reached it during a possible past stage where it was overflowing.
Lake San Agustín is a former lake in New Mexico, which developed as a pluvial lake in the Plains of San Agustín during Pleistocene glacial periods. During its highstands it covered an area of 1,200 square kilometres (460 sq mi) with a maximum depth of 70 metres (230 ft), and split into several separate lakes while drying out. The lake last appeared during the last glacial maximum (LGM) and dried out at the beginning of the Holocene, with the last remnant disappearing about 5,000 years ago.
