Recent uplift of Manitoulin Island, Ontario

1970 ◽  
Vol 7 (2) ◽  
pp. 665-675 ◽  
Author(s):  
C. F. M. Lewis
Keyword(s):  
Lake Level ◽  
High Energy ◽  
Lake Huron ◽  
Level Gauge ◽  
Lake Levels ◽  
Radiocarbon Dates ◽  
The Past ◽  
Organic Sediment ◽  
Constant Rate ◽  
Beach Sediments

Differential postglacial uplifting in the Huron basin has long been recognized from the observed deformation of raised shorelines, particularly those associated with the Algonquin series of glacial lakes (12 000–10 500 years B.P.) and the postglacial Nipissing Great Lakes. From Nipissing time, about 5500 years B.P., to the present, lake levels apparently fell in the northern Huron – Georgian Bay region as the basin upwarped and the outlet was downcut.Recent emergence of Manitoulin Island in northern Lake Huron was inferred, independently of raised shoreline data, from sediment sequences in a series of 3 beach sites and 8 small lake basins at various altitudes up to 20 m above Lake Huron. Organic sediment (gyttja) in each lake overlies clastic inorganic sand or silt, with the contact horizon demarcating the isolation of each basin as its threshold emerged from the high-energy littoral environment of Lake Huron. Radiocarbon dates and elevations of the basal gyttja sediments and organic beach sediments suggest uplift at a constant rate of 2.2 mm/year over the past 5000 years. This rate refers to Little Current, Ontario, and is for movement relative to the outlet area of Huron basin at Sarnia, Ontario. The value agrees with basin tilting inferred from lake level gauge observations made during the last 100 years.

Quantifying recent lake level changes in Patagonia (Argentina and Chile): Back to the future?

2021 ◽  
Author(s):  
Daniel Ariztegui ◽  
Clément Pollier ◽  
Andrés Bilmes
Keyword(s):  
Water Level ◽  
Lake Level ◽  
Satellite Images ◽  
Meteorological Data ◽  
Tierra Del Fuego ◽  
Water Level Fluctuations ◽  
Lake Levels ◽  
The Past ◽  
Rainfall Variations ◽  
The Impact

<p>Lake levels in hydrologically closed-basins are very sensitive to climatically and/or anthropogenically triggered environmental changes. Their record through time can provide valuable information to forecast changes that can have substantial economical and societal impact.</p><p>Increasing precipitation in eastern Patagonia (Argentina) have been documented following years with strong El Niño (cold) events using historical and meteorological data. Quantifying changes in modern lake levels allow determining the impact of rainfall variations while contributing to anticipate the evolution of lacustrine systems over the next decades with expected fluctuations in ENSO frequencies. Laguna Carrilaufquen Grande is located in the intermontane Maquinchao Basin, Argentina. Its dimension fluctuates greatly, from 20 to 55 km<sup>2</sup> water surface area and an average water depth of 3 m. Several well-preserved gravelly beach ridges witness rainfall variations that can be compared to meteorological data and satellite images covering the last ~50 years. Our results show that in 2016 lake level was the lowest of the past 44 years whereas the maximum lake level was recorded in 1985 (+11.8 m above the current lake level) in a position 1.6 km to the east of the present shoreline. A five-years moving average rainfall record of the area was calculated smoothing the extreme annual events and correlated to the determined lake level fluctuations. The annual variation of lake levels was up to 1.2 m (e.g. 2014) whereas decadal variations related to humid-arid periods for the interval 2002 to 2016 were up to 9.4 m. These data are consistent with those from other monitored lakes and, thus, our approach opens up new perspectives to understand the historical water level fluctuations of lakes with non-available monitoring data.</p><p> </p><p>Laguna de los Cisnes in the Chilean section of the island of Tierra del Fuego, is a closed-lake presently divided into two sections of 2.2 and 11.9 km<sup>2</sup>, respectively. These two water bodies were united in the past forming a single larger lake. The lake level was  ca. 4 m higher than today as shown by clear shorelines and the outcropping of large Ca-rich microbialites. Historical data, aerial photographs and satellite images indicate that the most recent changes in lake level are the result of a massive decrease of water input during the last half of the 20<sup>th</sup> century triggered by an indiscriminate use of the incoming water for agricultural purposes. The spectacular outcropping of living and fossil microbialites is not only interesting from a scientific point of view but has also initiated the development of the site as a local touristic attraction. However, if the use of the incoming water for agriculture in the catchment remains unregulated the lake water level might drop dangerously and eventually the lake might fully desiccate.</p><p>These two examples illustrate how recent changes in lake level can be used to anticipate the near future of lakes. They show that ongoing climate changes along with the growing demand of natural resources have already started to impact lacustrine systems and this is likely to increase in the decades to come.</p>

Dominance of an ∼150-Year Cycle of Sand-Supply Change in Late Holocene Dune-Building along the Eastern Shore of Lake Michigan

2000 ◽  
Vol 54 (3) ◽  
pp. 414-422 ◽  
Author(s):  
Walter L. Loope ◽  
Alan F. Arbogast
Keyword(s):  
Lake Level ◽  
Late Holocene ◽  
Lake Michigan ◽  
Probability Distributions ◽  
Buried Soils ◽  
Lake Levels ◽  
Eastern Shore ◽  
Soil Burial ◽  
The Past ◽  
Sand Supply

Outcrops of buried soils on lake-plains and glacial headlands along Lake Michigan's eastern shore suggest that periodic dune-building has occurred there after relatively long (≥100 yr) periods of low sand supply. We located, described, and radiocarbon dated 75 such buried soils that crop out in 32 coastal dune fields beside the lake. We assume that peaks in probability distributions of calibrated 14C ages obtained from wood, charcoal, and other organic matter from buried A horizons approximate the time of soil burial by dunes. Plotted against a late Holocene lake-level curve for Lake Michigan, these peaks are closely associated with many ∼150-yr lake highstands previously inferred from beach ridge studies. Intervening periods of lower lake levels and relative sand starvation apparently permitted forestation and soil development at the sites we studied. While late Holocene lake-level change led to development and preservation of prominent foredunes along the southern and southwestern shores of Lake Michigan, the modern dune landscape of the eastern shore is dominated by perched dunes formed during ∼150-yr lake highstands over the past 1500 yr.

scholarly journals The late Holocene record of Lake Mareotis, Nile Delta, Egypt

2021 ◽  
Vol 70 (1) ◽  
pp. 93-104
Author(s):  
Clément Flaux ◽  
Matthieu Giaime ◽  
Valérie Pichot ◽  
Nick Marriner ◽  
Mena el-Assal ◽  
...  
Keyword(s):  
Lake Level ◽  
Nile Delta ◽  
High Energy ◽  
Isotopic Signature ◽  
Nile Valley ◽  
Faunal Remains ◽  
Human Occupation ◽  
Radiocarbon Dates ◽  
Lake Level Changes ◽  
Lake Maryut

Abstract. Lake Maryut (northwestern Nile Delta, Egypt) was a key feature of Alexandria's hinterland and economy during Greco-Roman times. Its shores accommodated major economic centers, and the lake acted as a gateway between the Nile valley and the Mediterranean. It is suggested that lake-level changes, connections with the Nile and the sea, and possible high-energy events considerably shaped the human occupation history of the Maryut. To reconstruct Lake Maryut hydrology in historical times, we used faunal remains, geochemistry (Sr isotopic signature of ostracods) and geoarcheological indicators of relative lake-level changes. The data show both a rise in Nile inputs to the basin during the first millennia BCE and CE and a lake-level rise of ca. 1.5 m during the Roman period. A high-energy deposit, inferred from reworked radiocarbon dates, may explain an enigmatic sedimentary hiatus previously attested to in Maryut's chronostratigraphy.

Radiocarbon Reservoir Effect and the Timing of the Late-Glacial/Early Holocene Humid Phase in the Atacama Desert (Northern Chile)

1999 ◽  
Vol 52 (2) ◽  
pp. 143-153 ◽  
Author(s):  
Mebus A. Geyh ◽  
Martin Grosjean ◽  
Lautaro Núñez ◽  
Ulrich Schotterer
Keyword(s):  
Lake Level ◽  
Atacama Desert ◽  
Late Glacial ◽  
Early Holocene ◽  
Vegetation Changes ◽  
Northern Chile ◽  
Lake Levels ◽  
Human Occupation ◽  
Radiocarbon Dates ◽  
History Of

We revise substantially the regional chronology of lake-level fluctuations from the late-glacial/early Holocene humid phase along a high altitude transect (3500 to 4500 m) between 18°S and 28°S in the Southwestern Altiplano of Northern Chile. Radiocarbon dates and 210Pb profiles for limnic and terrestrial materials allow us to estimate and justify reservoir correction values for conventional 14C dates. Our chronology suggests that the latest Pleistocene/early Holocene humid phase started between 13,000 and 12,000 14C yr B.P., and that maximum lake levels were reached between 10,800 and 9200 14C yr B.P. This is significantly younger than what has been established so far for the Titicaca–Uyuni Basin in Bolivia. The paleolakes disappeared sometime between 8400 and 8000 14C yr B.P. Our revised chronology agrees with the regional history of human occupation, and is broadly synchronous with vegetation changes in subtropical continental South America, and with the onset of wetland expansion in the northern hemisphere tropics.

scholarly journals Holocene palaeohydrological changes in the northern Mediterranean borderlands as reflected by the lake-level record of lake ledro, northeastern Italy

2012 ◽  
Vol 77 (3) ◽  
pp. 382-396 ◽  
Author(s):  
Michel Magny ◽  
Sébastien Joannin ◽  
Didier Galop ◽  
Boris Vannière ◽  
Jean Nicolas Haas ◽  
...  
Keyword(s):  
North Atlantic ◽  
Lake Level ◽  
Lake Levels ◽  
Radiocarbon Dates ◽  
The North ◽  
Northeastern Italy ◽  
Insolation Maximum ◽  
Summer Rain ◽  
North Atlantic Area ◽  
Atlantic Area

A lake-level record of Lake Ledro (northern Italy) spans the entire Holocene with a chronology derived from 51 radiocarbon dates. It is based on a specific sedimentological approach that combines data from five sediment profiles sampled in distinct locations in the littoral zone. On a millennial scale, the lake-level record shows two successive periods from 11,700 to 4500 cal yr BP and from 4500 cal yr BP to the present, characterized by lower and higher average lake levels, respectively. In addition to key seasonal and inter-hemispherical changes in insolation, the major hydrological change around 4500 cal yr BP may be related to a non-linear response of the climate system to orbitally-driven gradual decrease in insolation. The Ledro record questions the notion of an accentuated summer rain regime in the northern Mediterranean borderlands during the boreal insolation maximum. Moreover, the Ledro record highlights that the Holocene was punctuated by successive centennial-scale highstands. Correlations with the Preboreal oscillation and the 8.2 ka event, and comparison with the atmospheric 14C residual record, suggest that short-lived lake-level fluctuations developed at Ledro in response to (1) final steps of the deglaciation in the North Atlantic area and (2) variations in solar activity.

Lake-Level Reconstruction and Paleohydrology of Birch Lake, Central Alaska, Based on Seismic Reflection Profiles and Core Transects

2000 ◽  
Vol 53 (2) ◽  
pp. 154-166 ◽  
Author(s):  
Mark B. Abbott ◽  
Bruce P. Finney ◽  
Mary E. Edwards ◽  
Kerry R. Kelts
Keyword(s):  
Seismic Reflection ◽  
Lake Level ◽  
Sediment Cores ◽  
Lake Levels ◽  
Seismic Profiles ◽  
Vegetation Development ◽  
Radiocarbon Dates ◽  
Seasonally Dry ◽  
Sedimentary Sequences ◽  
Seismic Reflection Profiles

AbstractLake-level history for Birch Lake, Alaska, was reconstructed using seismic profiles and multiproxy sedimentary analyses including sedimentology, geochemistry, magnetic susceptibility, and palynology. Twenty-two seismic profiles (18 km total) and eight sediment cores taken from the lake margin to its depocenter at 13.5 m provide evidence for low lake stands during the late Pleistocene and Holocene. Thirty-one AMS radiocarbon dates of macrofossils and pollen provide a century-scale chronology. Prior to 12,700 14C yr B.P., the lake, which now overflows, was either seasonally dry or desiccated for prolonged periods, indicating a severe period of aridity. Lake level rose more than 18 m between 12,700 and 12,200 14C yr B.P. before falling to 17 m below the level of overflow. Between 11,600 and 10,600 14C yr B.P. the water remained between 14 and 17 m below the overflow level. Onlap sedimentary sequences were formed during a transgression phase between 10,600 and 10,000 14C yr B.P. Between 10,000 and about 8800 14C yr B.P. the lake was between 6 and 9 m below the overflow level. Lake level again rose, approaching the overflow level, between 8800 and 8000 14C yr B.P. Seismic and core evidence of minor erosional events suggest lowstands of 2–6 m until 4800 14C yr B.P. There have been no prolonged periods of lake-level depression since that time. The major restructuring of the climate system during deglaciation evidently generated a complex set of fluctuations in effective moisture in interior Alaska, which likely affected eolian processes and vegetation development, as well as lake levels.

scholarly journals Calibration of Radiocarbon Dates for the Late Pleistocene Using U/Th Dates on Stalagmites

Radiocarbon ◽  
1997 ◽  
Vol 39 (1) ◽  
pp. 27-32 ◽  
Author(s):  
John C. Vogel ◽  
Joel Kronfeld
Keyword(s):  
South Africa ◽  
Magnetic Dipole ◽  
Satisfactory Agreement ◽  
Late Pleistocene ◽  
Calibration Curve ◽  
Dipole Field ◽  
Radiocarbon Dates ◽  
The Past ◽  
The Earth ◽  
Magnetic Dipole Field

Twenty paired 14C and U/Th dates covering most of the past 50,000 yr have been obtained on a stalagmite from the Cango Caves in South Africa as well as some additional age-pairs on two stalagmites from Tasmania that partially fill a gap between 7 ka and 17 ka ago. After allowance is made for the initial apparent 14C ages, the age-pairs between 7 ka and 20 ka show satisfactory agreement with the coral data of Bard et al. (1990, 1993). The results for the Cango stalagmite between 25 ka and 50 ka show the 14C dates to be substantially younger than the U/Th dates except at 49 ka and 29 ka, where near correspondence occurs. The discrepancies may be explained by variations in 14C production caused by changes in the magnetic dipole field of the Earth. A tentative calibration curve for this period is offered.

scholarly journals The emerging technology of biohybrid micro-robots: a review

2021 ◽  
Author(s):  
Zening Lin ◽  
Tao Jiang ◽  
Jianzhong Shang
Keyword(s):  
Self Assembly ◽  
Degrees Of Freedom ◽  
High Energy ◽  
Living Cells ◽  
Multiple Degrees Of Freedom ◽  
The Past ◽  
Great Prevalence ◽  
Performance Decline ◽  
High Energy Efficiency ◽  
Living Tissues

Abstract In the past few decades, robotics research has witnessed an increasingly high interest in miniaturized, intelligent, and integrated robots. The imperative component of a robot is the actuator that determines its performance. Although traditional rigid drives such as motors and gas engines have shown great prevalence in most macroscale circumstances, the reduction of these drives to the millimeter or even lower scale results in a significant increase in manufacturing difficulty accompanied by a remarkable performance decline. Biohybrid robots driven by living cells can be a potential solution to overcome these drawbacks by benefiting from the intrinsic microscale self-assembly of living tissues and high energy efficiency, which, among other unprecedented properties, also feature flexibility, self-repair, and even multiple degrees of freedom. This paper systematically reviews the development of biohybrid robots. First, the development of biological flexible drivers is introduced while emphasizing on their advantages over traditional drivers. Second, up-to-date works regarding biohybrid robots are reviewed in detail from three aspects: biological driving sources, actuator materials, and structures with associated control methodologies. Finally, the potential future applications and major challenges of biohybrid robots are explored. Graphic abstract

scholarly journals Hydroclimate variability in the low-elevation Atacama Desert over the last 2500 yr

2012 ◽  
Vol 8 (1) ◽  
pp. 287-306 ◽  
Author(s):  
E. M. Gayo ◽  
C. Latorre ◽  
C. M. Santoro ◽  
A. Maldonado ◽  
R. De Pol-Holz
Keyword(s):  
Hydrological Cycle ◽  
Atacama Desert ◽  
Plant Macrofossils ◽  
Central Andes ◽  
Tropical Pacific ◽  
Riparian Ecosystems ◽  
Independent Evidence ◽  
Radiocarbon Dates ◽  
Climate Fluctuations ◽  
The Past

Abstract. Paleoclimate reconstructions reveal that Earth system has experienced sub-millennial scale climate changes over the past two millennia in response to internal/external forcing. Although sub-millennial hydroclimate fluctuations have been detected in the central Andes during this interval, the timing, magnitude, extent and direction of change of these events remain poorly defined. Here, we present a reconstruction of hydroclimate variations on the Pacific slope of the central Andes based on exceptionally well-preserved plant macrofossils and associated archaeological remains from a hyperarid drainage (Quebrada Maní, ∼21° S, 1000 m a.s.l.) in the Atacama Desert. During the late Holocene, riparian ecosystems and farming social groups flourished in the hyperarid Atacama core as surface water availability increased throughout this presently sterile landscape. Twenty-six radiocarbon dates indicate that these events occurred between 1050–680, 1615–1350 and 2500–2040 cal yr BP. Regional comparisons with rodent middens and other records suggest that these events were synchronous with pluvial stages detected at higher-elevations in the central Andes over the last 2500 yr. These hydroclimate changes also coincide with periods of pronounced SST gradients in the Tropical Pacific (La Niña-like mode), conditions that are conducive to significantly increased rainfall in the central Andean highlands and flood events in the low-elevation watersheds at inter-annual timescales. Our findings indicate that the positive anomalies in the hyperarid Atacama over the past 2500 yr represent a regional response of the central Andean climate system to changes in the global hydrological cycle at centennial timescales. Furthermore, our results provide support for the role of tropical Pacific sea surface temperature gradient changes as the primary mechanism responsible for climate fluctuations in the central Andes. Finally, our results constitute independent evidence for comprehending the major trends in cultural evolution of prehistoric peoples that inhabited the region.

scholarly journals Chlorine-free synthesis: An overview

2012 ◽  
Vol 84 (3) ◽  
pp. 411-423 ◽  
Author(s):  
Pietro Tundo
Keyword(s):  
Climate Change ◽  
Industrial Revolution ◽  
High Energy ◽  
Special Topic ◽  
Ozone Layer Depletion ◽  
The Past ◽  
Process Chemistry ◽  
End Products ◽  
Chemical Strategies ◽  
Topic Issue

Since the Industrial Revolution, chlorine has featured as an iconic molecule in process chemistry even though its production by electrolysis of sodium chloride is very energy-intensive. Owing to its high energy and reactivity, chlorine allows the manufacture of chlorinated derivatives in a very easy way: AlCl3, SnCl4, TiCl4, SiCl4, ZnCl2, PCl3, PCl5, POCl3, COCl2, etc. in turn are pillar intermediates in the production of numerous everyday goods. This kind of chloride chemistry is widely used because the energy is transferred to these intermediates, making further syntheses easy. The environmental and health constraints (toxicity and eco-toxicity, ozone layer depletion) and the growing need for energy (energy efficiency, climate change) force us to take advantage from available knowledge to develop new chemical strategies. Substitution of chlorine in end products in compounds where “chlorine is used in the making” means that we avoid electrolysis as primary energetic source; this makes chemistry “without chlorine” considerably more difficult and illustrates why it has not found favor in the past. The rationale behind this Special Topic issue is to seek useful and industrially relevant examples for alternatives to chlorine in synthesis, so as to facilitate the development of industrially relevant and implementable breakthrough technologies.

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