Glacial and early postglacial lacustrine environment of a portion of northeastern Lake Ontario

1992 ◽  
Vol 29 (1) ◽  
pp. 63-75 ◽  
Author(s):  
Robert Gilbert ◽  
John Shaw
Keyword(s):  
Lake Ontario ◽  
Late Glacial ◽  
High Energy ◽  
Upper Great Lakes ◽  
Glacial Sediments ◽  
The North ◽  
Large Channel ◽  
Acoustic Facies ◽  
Short Time ◽  
Subglacial Meltwater

A deep channel in bedrock extending to more than 25 m below sea level occurs along the north shore of the otherwise uniformly shallow Kingston basin of Lake Ontario. Bathymetric and subbottom acoustic data are used to map the topography of the channel and to reconstruct its late glacial and postglacial sedimentary history. The results are interpreted as showing that the large channel and smaller channels nearby were created by high-velocity subglacial meltwater flow. Acoustic facies assemblages of sediments deposited in the channels record patchy deposition, or deposition followed by partial erosion, of glacial sediments on the bedrock of the channel floor, followed by deposition and episodic erosion of glaciolacustrine sediment in a high-energy, ice-proximal lake. Palaeoslope analysis confirms that the early Holocene low-water phase of Lake Ontario resulted in the development of a fluvial system in part of the channel. Water level was controlled by a sill at Kingston. Kingston basin, the Bay of Quinte, and possibly, for a short time, a much larger area of the upper Great Lakes drained through the channel. However, for most of the period, until it was flooded by the rising waters of Lake Ontario, the channel was occupied by a small river on a wide floodplain or it was flanked by broad marshes.

Pollen and Oxygen Isotope Analyses on Late- and Post-Glacial Sediments of the Tourbière de Chirens (Dauphiné, France)

1981 ◽  
Vol 15 (2) ◽  
pp. 160-170 ◽  
Author(s):  
U. Eicher ◽  
U. Siegenthaler ◽  
S. Wegmüller
Keyword(s):  
Pollen Analysis ◽  
Younger Dryas ◽  
Late Glacial ◽  
Glacial Sediments ◽  
Abrupt Changes ◽  
Climatic Transition ◽  
Climatic History ◽  
The Alps ◽  
Short Time ◽  
Isotope Analyses

AbstractThe sequence of vegetation phases in the late Glacial was studied in a sediment section from the bog Tourbière de Chirens by means of pollen analysis. 18O/16O ratios of samples of lacustrine marl, obtained from the same profile, reflect variations of 18O/16O in precipitation and thus provide an additional, independent paleoclimatic record. The observed 18O/16O variations agree well with the climatic history as deduced from pollen analysis. The climatic transition from the Oldest Dryas to the Bølling period sensu lato, as well as the beginning and end of the Younger Dryas cold phase, is marked by abrupt changes in the 18O/16O ratio which were observed also in other regions of the Alps. These drastic climatic changes probably took place simultaneously over large areas of Central Europe and occurred within short time spans.

Sedimentary record of Harrison Lake: implications for deglaciation in southwestern British Columbia

1991 ◽  
Vol 28 (5) ◽  
pp. 800-815 ◽  
Author(s):  
Joseph R. Desloges ◽  
Robert Gilbert
Keyword(s):  
Surface Sediments ◽  
Hot Springs ◽  
Late Glacial ◽  
High Energy ◽  
The South ◽  
Sedimentary Record ◽  
Sea Levels ◽  
Transparent Layer ◽  
The North ◽  
Lake Cores

A sedimentary record from 60 km long Harrison Lake was constructed by using 3.5 kHz subbottom acoustic profiles and gravity cores of surface sediments. In places, the glaciolacustrine sediments exceed 70 m in thickness and represent the entire deglacial and postglacial accumulation record. An upper, acoustically transparent layer decreases in thickness from 12 to 4 m. southward from the upper lake. Cores from the upper metre of this layer demonstrate that deposition is dominated by settling of suspended sediment transported in a laterally mixed, wind-driven surface plume from the north. Depositional rates, inferred from 14C dating of organic macrofossils and counting of probable annual laminated couplets in the cores, are almost 2 mm/a in the north and decline to less than 0.1 mm/a in the south. Hence, the upper acoustic layer accounts for all postglacial (last 10 500 years BP) lacustrine deposition, with most of the sediment derived from Lillooet River. A lower, thicker (12–22 m), acoustically stratified layer is interpreted as high-energy glaciolacustrine deposits. This large volume of deglaciation sediment is derived from two sources: (i) ice retreating rapidly northwest up the Lillooet valley, which may have existed for no more than 400 years in the lower valley prior to opening of Lillooet Lake (which now traps most sediment derived from the upper basin); and (ii) inflow from the south as the late-glacial Fraser River rapidly built a delta north from the sill at Harrison Hot Springs. Despite known higher sea levels during deglaciation of the eastern Fraser Lowland, we have no evidence for a marine incursion.

Sediments of the Tay Estuary. VI. Sediments of the lower and outer reaches

1980 ◽  
Vol 78 (3-4) ◽  
pp. s133-s153
Author(s):  
J. McManus ◽  
A. T. Buller ◽  
C. D. Green
Keyword(s):  
North Sea ◽  
Late Glacial ◽  
Short Time Scale ◽  
Size Frequency Distribution ◽  
The North ◽  
Constant State ◽  
Repeated Sampling ◽  
The North Sea ◽  
Short Time ◽  
Marine Clays

SynopsisThe main channels converge at Dundee and form a single outlet passing seawards of the Broughty Ferry-Tayport constriction. The coarsest sediments, often of gravels and shell debris, line the floor of the channel, which is locally cut into late-glacial marine clays. Extensive sandy tidal flats seaward of the constriction pass eastwards into dune-covered sand spits pointing into the North Sea. The entrance bar has a delta-like form which is slowly overriding the fine sands of the North Sea floor.The median, sorting, and skewness of the sediments, and the covariation of several parameters follow patterns readily related to the physiographic features of the estuary.Many of the beach and tidal flat areas are in a constant state of change, and repeated topographic surveying reveals the magnitude of these changes on a short time scale. The changes in sediment characteristics demonstrated by repeated sampling and analysis of material from one stretch of Broughty Ferry beach are substantial. Size-frequency distribution plots indicate that up to four sub-populations of grains are present. Natural combinations of these in different proportions produce systematic variations in values of the normally used sediment characterising statistics.

A palynological investigation of true-moss (Bryidae) spores: morphology and occurrence in modern and late Quaternary lake sediments of Alaska

1998 ◽  
Vol 76 (12) ◽  
pp. 2145-2157 ◽  
Author(s):  
L B Brubaker ◽  
P M Anderson ◽  
B M Murray ◽  
D Koon
Keyword(s):  
Boreal Forest ◽  
Late Quaternary ◽  
Late Glacial ◽  
North Slope ◽  
Wall Structure ◽  
Herbarium Specimens ◽  
Glacial Sediments ◽  
The North ◽  
True Moss ◽  
Southwestern Alaska

This study describes (i) spore morphology of 121 Alaskan species of true moss (Bryidae) and (ii) percentages of Bryidae and Sphagnum spores in mud-water interface samples from 46 Alaskan lakes and a late-Quaternary sediment core from Idavain Lake in southwestern Alaska. Bryidae spores were collected from herbarium specimens, prepared by standard palynological chemical treatment and described under light microscopy. An identification key based on spore shape, wall structure, and size recognized 11 major morphological groups. Although family, genus, or species identifications were not possible for most groups, spores of a few genera and species were distinctive. Bryidae spores occurred in 80% of the modern sediment samples, representing boreal forest and three areas of tundra (North Slope, Seward Peninsula, and southwestern Alaska). Bryidae and Sphagnum spore percentages showed greatest differences between the North Slope tundra and other vegetation types, whereas pollen percentages distinguished boreal forest from tundra regions as a group. Bryidae spores were present throughout the Idavain Lake record but were most common in late-glacial sediments. Variations in the abundance of Bryidae spores are consistent with or enhance paleoenvironmental interpretations based on pollen and other spore types.Key words: Bryidae, palynology, spores, Alaska, Quaternary, paleoenvironment.

scholarly journals Stratigraphic Architecture and Sediment Facies of the Western Oak Ridges Moraine, Humber River Watershed, Southern Ontario*

2006 ◽  
Vol 58 (2-3) ◽  
pp. 241-267 ◽  
Author(s):  
Hazen A.J. Russell ◽  
Robert W.C. Arnott ◽  
David R. Sharpe
Keyword(s):  
Ice Sheet ◽  
Lake Ontario ◽  
Late Glacial ◽  
Southern Ontario ◽  
Oak Ridges Moraine ◽  
River Watershed ◽  
Subglacial Lake ◽  
Humber River ◽  
Sand And Gravel ◽  
Subglacial Meltwater

Abstract The Oak Ridges Moraine in southern Ontario is a ca. 160 km long east-west trending ridge of sand and gravel situated north of Lake Ontario. Study of the Oak Ridges Moraine in the Humber River watershed was undertaken to assess its role in the groundwater system of the buried Laurentian Valley. The Oak Ridges Moraine is interpreted to have been deposited in three stages. Stage I records rapid deposition from hyperconcentrated flows where tunnel channels discharged into a subglacial lake in the Lake Ontario basin. Low-energy basin sedimentation of Stage II was in a subglacial and ice-contact setting of a highly crevassed ice sheet. Stage III sedimentation is characterized by rapid facies changes associated with esker, subaqueous fan, and basinal sedimentation. Detailed sediment analysis challenges the concept that the Oak Ridges Moraine was deposited principally from seasonal meltwater discharges, climatic modulated ice-marginal fluctuations, or in an interlobate position. Instead it is interpreted to have formed in response to late-glacial ice sheet events associated with subglacial meltwater ponding, episodic and catastrophic subglacial meltwater discharge, and subsequent seasonal meltwater discharge. The moraine probably formed as the glacial-hydraulic system re-equilibrated to the presence of a thinned, grounded ice shelf and a subglacial lake in the Lake Ontario basin.

Loadings of Selected Chemicals into the St. Lawrence River System from Lake Ontario, 1986/87

1989 ◽  
Vol 24 (4) ◽  
pp. 589-608 ◽  
Author(s):  
I.K. Tsanis ◽  
J. Biberhofer ◽  
C.R. Murthy ◽  
A. Sylvestre
Keyword(s):  
Mass Balance ◽  
Lake Ontario ◽  
River System ◽  
Vertical Gradient ◽  
The South ◽  
Measured Concentration ◽  
Chemical Monitoring ◽  
The North ◽  
Loading Estimates ◽  
St Lawrence River

Abstract Determination of the mass output through the St. Lawrence River outflow system is an important component in computing mass balance of chemical loadings to Lake Ontario. The total flow rate in the St. Lawrence River System at the Wolfe Island area was calculated from detailed time series current meter measurements from a network of current meters and Lagrangian drifter experiments. This flow is roughly distributed in the ratio of 55% to 45% in the South and North channel, respectively. Loading estimates of selected chemicals have been made by combining the above transport calculations with the ongoing chemical monitoring data at the St. Lawrence outflow. A vertical gradient in the concentration of some organic and inorganic chemicals was observed. The measured concentration for some of the chemicals was higher during the summer months and also is higher in the South Channel than in the North Channel of the St. Lawrence River. These loading estimates are useful not only for modelling the mass balance of chemicals in Lake Ontario but also for serving as input loadings to the St. Lawrence River system from Lake Ontario.

Conflict, Population Movement, and Microscale Social Networks in Northern Iroquoian Archaeology

2021 ◽  
Vol 86 (2) ◽  
pp. 350-367
Author(s):  
Jennifer Birch ◽  
John P. Hart
Keyword(s):  
Social Networks ◽  
Sixteenth Century ◽  
Lake Ontario ◽  
Population Movement ◽  
Network Ties ◽  
The West ◽  
Local Networks ◽  
North Shore ◽  
The North ◽  
Specific Sequences

We employ social network analysis of collar decoration on Iroquoian vessels to conduct a multiscalar analysis of signaling practices among ancestral Huron-Wendat communities on the north shore of Lake Ontario. Our analysis focuses on the microscale of the West Duffins Creek community relocation sequence as well as the mesoscale, incorporating several populations to the west. The data demonstrate that network ties were stronger among populations in adjacent drainages as opposed to within drainage-specific sequences, providing evidence for west-to-east population movement, especially as conflict between Wendat and Haudenosaunee populations escalated in the sixteenth century. These results suggest that although coalescence may have initially involved the incorporation of peoples from microscale (local) networks, populations originating among wider mesoscale (subregional) networks contributed to later coalescent communities. These findings challenge previous models of village relocation and settlement aggregation that oversimplified these processes.

scholarly journals A quasi-monoenergetic short time duration compact proton source for probing high energy density states of matter

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
J. I. Apiñaniz ◽  
S. Malko ◽  
R. Fedosejevs ◽  
W. Cayzac ◽  
X. Vaisseau ◽  
...  
Keyword(s):  
Energy Density ◽  
Proton Beam ◽  
Dense Matter ◽  
High Energy ◽  
High Repetition Rate ◽  
High Energy Density ◽  
Time Duration ◽  
Ultrashort Pulse Laser ◽  
Proton Source ◽  
Short Time

AbstractWe report on the development of a highly directional, narrow energy band, short time duration proton beam operating at high repetition rate. The protons are generated with an ultrashort-pulse laser interacting with a solid target and converted to a pencil-like narrow-band beam using a compact magnet-based energy selector. We experimentally demonstrate the production of a proton beam with an energy of 500 keV and energy spread well below 10$$\% $$ % , and a pulse duration of 260 ps. The energy loss of this beam is measured in a 2 $$\upmu $$ μ m thick solid Mylar target and found to be in good agreement with the theoretical predictions. The short time duration of the proton pulse makes it particularly well suited for applications involving the probing of highly transient plasma states produced in laser-matter interaction experiments. This proton source is particularly relevant for measurements of the proton stopping power in high energy density plasmas and warm dense matter.

Sign in / Sign up

Export Citation Format

Share Document