The age of the Hartman moraine and the Campbell beach of Lake Agassiz in northwestern Ontario

1982 ◽  
Vol 19 (10) ◽  
pp. 1933-1937 ◽  
Author(s):  
Erik Nielsen ◽  
W. Brian McKillop ◽  
James P. McCoy
Keyword(s):  
Water Level ◽  
Hard Water ◽  
High Water ◽  
Water Effect ◽  
Lake Agassiz ◽  
Red Clay ◽  
Radiocarbon Dates ◽  
Freshwater Molluscs ◽  
Northwestern Ontario ◽  
Freshwater Mollusc

Fluctuations in the level of Lake Agassiz are dated at two sites in northwestern Ontario. A radiocarbon date on a modern shell sample indicates dates on freshwater molluscs from the area are about 440 ± 100 years (GSC-3281) too old due to the hard-water effect. An adjustment of 400 years to two fossil freshwater mollusc dates of 11 400 ± 410 (GSC-3114) and 10 400 ± 100 years BP (GSC-2968) makes them compatible with radiocarbon dates on wood from deposits in other parts of the Lake Agassiz basin. The two new dates indicate the beginning of the low-water Moorhead Phase of Lake Agassiz started about 11 000 years BP. The high-water Emerson Phase started when the water level rose to form the Upper Campbell beach approximately 10 000 years BP. The red clay widely distributed throughout northwestern Ontario was deposited during the Emerson Phase when the ice margin lay along the Hartman, Dog Lake, and Marks moraines.

Origin and paleoecology of post-Lake Agassiz raised beaches in Manitoba

1987 ◽  
Vol 24 (7) ◽  
pp. 1478-1485 ◽  
Author(s):  
Erik Nielsen ◽  
David H. McNeil ◽  
W. Brian McKillop
Keyword(s):  
High Salinity ◽  
Marine Invertebrates ◽  
Hard Water ◽  
Present Level ◽  
Water Effect ◽  
Lake Agassiz ◽  
Marine Animals ◽  
Fossil Assemblages ◽  
Raised Beaches

Post-Lake Agassiz raised beaches have been identified 6 m above the present level of Lake Winnipegosis. The level, termed the Dawson level, is radiocarbon dated at 4870 ± 80 years BP (GSC-4138) and 4900 ± 70 years BP (GSC-4139) at Dawson Bay and at 5050 ± 100 years BP (BGS-1126) at Denbeigh Point. The dates are estimated to be 350 years too old due to the hard-water effect and the Dawson level is believed to have formed about 4550 years ago. The 6 m drop in the level of the northern part of Lake Winnipegosis is attributed to isostatic tilting. The fossil assemblages of the beaches are the same and are dominated by the extinct gastropod Marstonia gelida. Two marine invertebrates, the foraminifer Elphidium gunteri and the ostracod Cytheromorpha fuscata, are present in the samples. These marine animals are believed to have been brought into the area by migrating waterfowl and to have survived because of the high salinity of the lake.

Lake and inland dunes as interconnected Systems: The story of Lake Tresssee and an adjacent dune field (Schleswig-Holstein, North Germany)

The Holocene ◽  
2020 ◽  
pp. 095968362098168
Author(s):  
Christian Stolz ◽  
Magdalena Suchora ◽  
Irena A Pidek ◽  
Alexander Fülling
Keyword(s):  
Water Level ◽  
Bronze Age ◽  
Environmental Changes ◽  
High Water ◽  
Alluvial Fan ◽  
Water Levels ◽  
Lake Area ◽  
Dune Field ◽  
The North ◽  
Sand Drift

The specific aim of the study was to investigate how four adjacent geomorphological systems – a lake, a dune field, a small alluvial fan and a slope system – responded to the same impacts. Lake Tresssee is a shallow lake in the North of Germany (Schleswig-Holstein). During the Holocene, the lake’s water surface declined drastically, predominately as a consequence of human impact. The adjacent inland dune field shows several traces of former sand drift events. Using 30 new radiocarbon ages and the results of 16 OSL samples, this study aims to create a new timeline tracing the interaction between lake and dunes, as well, as how both the lake and the dunes reacted to environmental changes. The water level of the lake is presumed to have peaked during the period before the Younger Dryas (YD; start at 10.73 ka BC). After the Boreal period (OSL age 8050 ± 690 BC) the level must have undergone fluctuations triggered by climatic events and the first human influences. The last demonstrable high water level was during the Late Bronze Age (1003–844 cal. BC). The first to the 9th century AD saw slightly shrinking water levels, and more significant ones thereafter. In the 19th century, the lake area was artificially reduced to a minimum by the human population. In the dunes, a total of seven different phases of sand drift were demonstrated for the last 13,000 years. It is one of the most precisely dated inland-dune chronologies of Central Europe. The small alluvial fan took shape mainly between the 13th and 17th centuries AD. After 1700 cal. BC (Middle Bronze Age), and again during the sixth and seventh centuries AD, we find enhanced slope activity with the formation of Holocene colluvia.

scholarly journals A re-evaluation of the occurrence of freshwater molluscs in the Kruger National Park

Koedoe ◽  
1998 ◽  
Vol 41 (1) ◽  
Author(s):  
K.N. De Kock ◽  
C.T. Wolmarans
Keyword(s):  
Species Diversity ◽  
National Park ◽  
Kruger National Park ◽  
Intermediate Hosts ◽  
Freshwater Molluscs ◽  
Freshwater Mollusc ◽  
Mollusc Species ◽  
Trematode Parasites

Most of the previous records of the freshwater molluscs from the Kruger National Park date back prior to and up to 1966. On account of several droughts between 1966 and 1995 it was decided to do a survey of the freshwater mollusc population in 1995 to evaluate the effect of these droughts. The traditional mollusc intermediate hosts were also screened for trematode parasites to establish whether or not they were infected. No infected molluscs were found. Eight of the 19 species reported up to 1966 were not found during the 1995 survey. Three new mollusc species were collected in 1995. The consequences of the drought are clearly visible when the species diversity found in the dams in the 1995 survey, is compared to what was previously recorded.

scholarly journals Proglacial river dataset from the Akuliarusiarsuup Kuua River northern tributary, Southwest Greenland, 2008–2010

2011 ◽  
Vol 4 (1) ◽  
pp. 71-97 ◽  
Author(s):  
A. K. Rennermalm ◽  
L. C. Smith ◽  
V. W. Chu ◽  
R. R. Forster ◽  
J. E. Box ◽  
...  
Keyword(s):  
Water Level ◽  
Statistical Tests ◽  
Ice Sheet ◽  
High Water ◽  
Stream Channels ◽  
Discharge Data ◽  
Lake Water Level ◽  
Considerable Uncertainty ◽  
Added Uncertainty ◽  
Southwest Greenland

Abstract. Pressing scientific questions concerning the Greenland ice sheet's climatic sensitivity, hydrology, and contributions to current and future sea level rise require hydrological datasets to resolve. While direct observations of ice sheet meltwater losses can be obtained in terrestrial rivers draining the ice sheet and from lake levels, few such datasets exist. We present a new dataset of meltwater river discharge for the vicinity of Kangerlussuaq, Southwest Greenland. The dataset contains measurements of river water level and discharge for three sites along the Akuliarusiarsuup Kuua (Watson) River's northern tributary, with 30 min temporal resolution between June 2008 and August 2010. Additional data of water temperature, air pressure, and lake water level and temperature are also provided. Discharge data were measured at sites with near-ideal properties for such data collection. Regardless, high water bedload and turbulent flow introduce considerable uncertainty. These were constrained and quantified using statistical techniques, which revealed that the greatest discharge data uncertainties are associated with streambed elevation change and measurements. Large portions of stream channels deepened according to statistical tests, but poor precision of streambed depth measurements also added uncertainty. Data will periodically be extended, and are available in Open Access at doi:10.1594/PANGAEA.762818.

scholarly journals NON-BREAKING AND BREAKING WAVE LOADS ON A COOLING WATER OUTFALL

1978 ◽  
Vol 1 (16) ◽  
pp. 148
Author(s):  
G.R. Mogridge ◽  
W.W. Jamieson
Keyword(s):  
Water Level ◽  
Cooling Water ◽  
High Water ◽  
Breaking Waves ◽  
Irregular Waves ◽  
Scale Model ◽  
Breaking Wave ◽  
Wave Loads ◽  
Eastern Canada ◽  
Spilling Breakers

Cooling water from a power generating station in Eastern Canada is pumped to an outfall and distributed into the ocean through discharge ports in the sidewalls of a diffuser cap. The cap is essentially a shell-type structure consisting of a submerged circular cylinder 26.5 ft in diameter and 14 ft high. It is located in 25 ft of water at low water level and 54 ft at high water level. Horizontal forces, vertical forces and overturning moments exerted by waves on a 1:36 scale model of the diffuser cap were measured with and without cooling water discharging from the outfall. Tests were run with regular and irregular waves producing both non-breaking and breaking wave loads on the diffuser cap. The overturning moments measured on the diffuser cap were up to 150 percent greater than those on a solid submerged cylinder sealed to the seabed. Unlike sealed cylinders, all of the wave loads measured on the relatively open structure reached maximum values at approximately the same time. The largest wave loads were measured on the diffuser structure when it was subjected to spilling breakers at low water level. For a given wave height, the spilling breakers caused wave loads up to 100 percent greater than those due to non-breaking waves.

scholarly journals Distribution of coastal high water level during extreme events around the UK and Irish coasts

2021 ◽  
Author(s):  
Julia Rulent ◽  
Lucy M. Bricheno ◽  
Mattias J. A. Green ◽  
Ivan D. Haigh ◽  
Huw Lewis
Keyword(s):  
Water Level ◽  
Extreme Events ◽  
High Tide ◽  
High Water ◽  
Relative Contribution ◽  
High Flood ◽  
Environmental Prediction ◽  
The Uk ◽  
Total Water Level ◽  
Tidal Stage

Abstract. The interaction between waves, surges and astronomical tides can lead to high coastal total water level (TWL), which can in turn lead to coastal flooding. Here, a high resolution (1.5 km) simulation from a UK-focused regional coupled environmental prediction system is used to investigate the extreme events of winter 2013/4 around the UK and Irish coasts. The aim is to analyse the spatial distribution of coastal TWL and its components during this period by assessing 1- the relative contribution of different TWL components around the coast, 2- how extreme waves, surges and tide interacted and if they occurred simultaneously 3- if this has implications in defining the severity of coastal hazard conditions. The TWL components’ coastal distribution in winter 2013/4 was not constant in space, impacting differently over different regions. High (> 90th percentile) waves and surges occurred simultaneously at any tidal stage, including high tide (7.7 % of cases), but more often over the flood tide. During periods of high flood risk a hazard proxy, defined as the sum of the sea surface height and half the significant wave height, at least doubled from average over ¾ of the coast. These results have important implications for the risk management sector.

Holocene evolution of the Assiniboine River paleochannels and Portage la Prairie alluvial fan

1989 ◽  
Vol 26 (9) ◽  
pp. 1834-1841 ◽  
Author(s):  
W. F. Rannie ◽  
L. H. Thorleifson ◽  
J. T. Teller
Keyword(s):  
Alluvial Fan ◽  
Red River ◽  
Lake Agassiz ◽  
Radiocarbon Dates ◽  
The Holocene ◽  
Sediment Loads ◽  
History Of ◽  
Western Side

The Portage la Prairie alluvial fan was constructed by numerous successive paleochannels of the Assiniboine River along the western side of the Lake Agassiz basin as the level of the lake rapidly declined beginning 9500 years ago. The history of the paleochannels during the first several thousand years is not known. Paleochannel morphologies and cross-cutting relations, soil maturity, and radiocarbon dates, however, indicate that by 6000–7000 years ago flow was northward into Lake Manitoba. This direction was maintained until about 3000 years ago, when avulsion redirected the Assiniboine eastward to the Red River near Winnipeg. The morphologies of the paleochannels suggest that channel-forming discharges and sediment loads of the ancestral rivers have not differed significantly from the modern values despite palynological evidence that the climate was warmer and drier during much of the Holocene.

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