CONTINUING HIGH LAKE LEVELS ARE LEADING TO SEVERE EROSION OF WESTERN LAKE SUPERIOR’S CLAY BLUFFS IN WISCONSIN

An extensive drilling program, undertaken along the western barrier bar at Point Pelee National Park, Ontario, Canada, yielded considerable subsurface sediment data relevant to the nature and lateral geometry of sedimentary units below the Point Pelee foreland. Four major sedimentary units were identified: a basal clay-rich till, a fine-grained glaciolacustrine sand, a medium-grained sand unit (subdivided into a poorly sorted shoreface sand and an aeolian (dune) sand derived from the shoreface sand), and an organic marsh (gyttja) deposit. The present study confirms the existence of a planar, wave-eroded till surface below the southern portion of Point Pelee at an elevation of approximately 164 m asl. Following this low-water period in the basin, lake levels rose abruptly to an elevation several metres above 172 m asl. This resulted in erosion of the upper part of the glaciolacustrine sand during a later period of stable higher lake levels, perhaps coinciding with the Nipissing flood event (about 4000 BP). This resulted in a planar surface at approximately 169.5 m asl. Several radiocarbon dates on basal gyttja from the marsh (averaging 3200 BP) reflect a subsequent drop in levels to about 2-3 m below present levels. Though undated, the initiation of shoreface and dune sand deposition is roughly coeval with the basal marsh deposits.

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Glacial and lake fluctuations in the area of the west Kunlun mountains during the last 45 000 years

Annals of Glaciology ◽

10.1017/s0260305500004857 ◽

1992 ◽

Vol 16 ◽

pp. 79-84 ◽

Cited By ~ 17

Author(s):

Liu Chaohai ◽

Li Shijie ◽

Shi Yafeng

Keyword(s):

Lacustrine Sediments ◽

Southern Slope ◽

Lake Levels ◽

Humid Climate ◽

The West ◽

Kunlun Mountains ◽

West Kunlun ◽

High Lake Levels ◽

The Last Glacial Maximum ◽

The Last Glacial

There appear to have been several important glacial advances on the southern slope of the west Kunlun mountains, Tibetan Plateau, since 45 000 a BP. Based on the record of alternating till and lacustrine sediments and 14C determinations, these advances are dated to 23 000–16 000, 8500–8000, and 4000–2500 a BP, and to the 16th–19th century AD, with regional variations occurring during each of the advances. The glaciation of 23 000–16 000 a BP is equivalent to the last glacial maximum (LGM) and its scope and scale were much larger than any of the others. Lake changes are a response to both tectonic uplift of the plateau and global climatic change. With regard to the latter, both changes in precipitation and changes in the extent of glaciation can affect lake levels. High lake levels occurred during interstadial conditions between 40 000 and 30 000 a BP, when the area experienced a relatively warm and humid climate, and during the LGM, between 21 000 and 15 000 a BP. During the Holocene, lakes have been shrinking gradually, coincident with the dry climate of this period of time.

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Glacial and lake fluctuations in the area of the west Kunlun mountains during the last 45 000 years

Annals of Glaciology ◽

10.3189/1992aog16-1-79-84 ◽

1992 ◽

Vol 16 ◽

pp. 79-84 ◽

Cited By ~ 3

Author(s):

Liu Chaohai ◽

Li Shijie ◽

Shi Yafeng

Keyword(s):

Lacustrine Sediments ◽

Southern Slope ◽

Lake Levels ◽

Humid Climate ◽

The West ◽

Kunlun Mountains ◽

West Kunlun ◽

High Lake Levels ◽

The Last Glacial Maximum ◽

The Last Glacial

There appear to have been several important glacial advances on the southern slope of the west Kunlun mountains, Tibetan Plateau, since 45 000 a BP. Based on the record of alternating till and lacustrine sediments and 14C determinations, these advances are dated to 23 000–16 000, 8500–8000, and 4000–2500 a BP, and to the 16th–19th century AD, with regional variations occurring during each of the advances. The glaciation of 23 000–16 000 a BP is equivalent to the last glacial maximum (LGM) and its scope and scale were much larger than any of the others.Lake changes are a response to both tectonic uplift of the plateau and global climatic change. With regard to the latter, both changes in precipitation and changes in the extent of glaciation can affect lake levels. High lake levels occurred during interstadial conditions between 40 000 and 30 000 a BP, when the area experienced a relatively warm and humid climate, and during the LGM, between 21 000 and 15 000 a BP. During the Holocene, lakes have been shrinking gradually, coincident with the dry climate of this period of time.

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Global Maps of Lake-Level Fluctuations since 30,000 yr B.P.

Quaternary Research ◽

10.1016/0033-5894(79)90092-9 ◽

1979 ◽

Vol 12 (1) ◽

pp. 83-118 ◽

Cited By ~ 415

Author(s):

F. Alayne Street ◽

A. T. Grove

Keyword(s):

Lake Level ◽

Ice Sheets ◽

Literature Survey ◽

Sea Surface ◽

Lake Levels ◽

Lake Level Fluctuations ◽

Average Abundance ◽

The Tropics ◽

High Lake Levels ◽

Precipitation And Temperature

This paper presents selected world maps of lake-level fluctuations since 30,000 yr B.P. These are based on a literature survey of 141 lake basins with radiocarbon-dated chronologies. The resulting patterns are subcontinental in scale and show orderly variations in space and time. They reflect substantial changes in continental precipitation, evaporation, and runoff, which are due to glacial/interglacial fluctuations in the atmospheric and oceanic circulations. In the tropics, high lake levels are essentially an interglacial or interstadial phenomenon, although there are important exceptions. Since extensive lakes during the Holocene corresponded with relatively high sea-surface temperatures, and therefore presumably with high evaporation rates on land, they are interpreted as the result of higher precipitation. Tropical aridity culminated in most areas at, or just after, the glacial maximum, although the present day is also characterized by a below-average abundance of surface water. In extratropical regions the mapped patterns are more complex. They vary markedly with latitude and proximity to major ice sheets. In these areas, evidence is at present insufficient to evaluate the relative contributions of precipitation and temperature to the observed lake-level record.

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Holocene Fluctuations of a Meromictic Lake in Southern British Columbia

Quaternary Research ◽

10.1006/qres.1997.1905 ◽

1997 ◽

Vol 48 (1) ◽

pp. 100-113 ◽

Cited By ~ 32

Author(s):

David J. Lowe ◽

John D. Green ◽

Tom G. Northcote ◽

Ken J. Hall

Keyword(s):

Saline Lake ◽

Basal Layer ◽

Climatic Changes ◽

Depositional Environments ◽

Laminated Sediments ◽

Lake Depth ◽

Lake Levels ◽

Short Term ◽

Northwestern North America ◽

High Lake Levels

Holocene deposits of Mahoney Lake, a meromictic saline lake located in a closed basin in the semi-arid Okanagan Valley, contain evidence of frequent and marked changes in lake depth (up to >12 m/10014C yr) probably caused by short-term changes in effective precipitation. We studied a 5.45-m-long core comprising a basal layer of inorganic mud overlain by a succession of layers of calcareous laminated and nonlaminated organic mud, marl, and sand. We used Mazama tephra to adjust nine radiocarbon ages for the hardwater effect. Meromixis developed ca. 900014C yr B.P., and the lake has been episodically meromictic for about half the time since. Because of close linkages between sediments and depositional environments in meromictic and saline lakes, we infer that laminated sediments indicate meromictic conditions and high lake levels (>ca. 12 m water depth), whereas thick marl layers and nonlaminated sediments indicate nonmeromictic conditions and thus low lake levels (<ca. 8 m depth). Many of the inferred short-term climatic changes have not been identified in previous studies in northwestern North America, perhaps because of insensitive climatic proxies, inadequate temporal resolution, or discounting of anomalous findings.

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Dating of the late Quaternary high lake levels in the Jilantai area, northwestern China, using optical luminescence of quartz and K-feldspar

Journal of Asian Earth Sciences ◽

10.1016/j.jseaes.2021.105024 ◽

2021 ◽

pp. 105024

Author(s):

Yuxin Fan ◽

Zhenjun Li ◽

Qingsong Cai ◽

Guangliang Yang ◽

Qingsong Zhang ◽

...

Keyword(s):

Late Quaternary ◽

Northwestern China ◽

Lake Levels ◽

Optical Luminescence ◽

High Lake Levels

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High precipitation and low evaporation resulted in high lake levels of the Juyanze paleolake, northwest China, during 34-26 cal kyr BP

Climate Research ◽

10.3354/cr01405 ◽

2016 ◽

Vol 69 (3) ◽

pp. 193-207 ◽

Cited By ~ 3

Author(s):

Z Li ◽

N Wang ◽

X Zhang ◽

H Cheng ◽

Y Li

Keyword(s):

Northwest China ◽

Lake Levels ◽

High Precipitation ◽

High Lake Levels

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Late Pleistocene lake level, glaciation and climate change in the Mongolian Altai deduced from sedimentological and palynological archives

Quaternary Research ◽

10.1017/qua.2020.67 ◽

2020 ◽

pp. 1-22

Author(s):

Michael Klinge ◽

Frank Schlütz ◽

Anja Zander ◽

Daniela Hülle ◽

Ochirbat Batkhishig ◽

...

Keyword(s):

Late Pleistocene ◽

Lake Level ◽

Lacustrine Sediments ◽

Glacial Period ◽

Lake Levels ◽

Apparent Contradiction ◽

Last Glacial ◽

Mongolian Altai ◽

High Lake Levels ◽

The Last Glacial

Abstract Glacial and lacustrine sediments from the Mongolian Altai provide paleoclimatic information for the late Pleistocene in Mongolia, for which only a few sufficiently studied archives exist. Glacial stages referred to global cooling events are reported for the last glacial maximum (27–21 ka) and the late glacial period (18–16 ka). Sedimentary archives from the first part of the last glacial period are infrequent. We present proxy data for this period from two different archives (88–63 and 57–30 ka). Due to the limitation of effective moisture, an increase of precipitation is discussed as one trigger for glacier development in the cold-arid regions of central Asia. Our pollen analysis from periods of high paleolake levels in small catchments indicate that the vegetation was sparse and of dry desert type between 42–29 and 17–11 ka. This apparent contradiction between high lake levels and dry landscape conditions, the latter supported by intensified eolian processes, points to lower temperatures and cooler conditions causing reduced evaporation to be the main trigger for the high lake levels during glacier advances. Rising temperatures that cause melting of glacier and permafrost ice and geomorphological processes play a role in paleolake conditions. Interpreting lake-level changes as regional or global paleoclimate signals requires detailed investigation of geomorphological settings and mountain–basin relationships.

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