THE BRYOPHYTE TORTELLA FLAVOVIRENS (BRUCH) BROTH. IN LATE GLACIAL SEDIMENTS FROM USSELO (THE NETHERLANDS) AND ITS SIGNIFICANCE AS A PALAEO-ENVIRONMENTAL INDICATOR

1983 ◽  
Vol 32 (5-6) ◽  
pp. 431-436 ◽  
Author(s):  
J. Wiegers ◽  
B. Van Geel
Keyword(s):  
The Netherlands ◽  
Late Glacial ◽  
Environmental Indicator ◽  
Glacial Sediments

Environmental magnetism study of Lake Cadagno, Switzerland

2021 ◽  
Author(s):  
Artin Ali ◽  
Andrea Biedermann ◽  
Jasmine Berg ◽  
Mark Lever ◽  
Hendrik Vogel
Keyword(s):  
Grain Size ◽  
Sedimentary Environment ◽  
Environmental Magnetism ◽  
Late Glacial ◽  
Magnetic Minerals ◽  
Climate Conditions ◽  
Glacial Sediments ◽  
Depth Profiles ◽  
Magnetic Carriers ◽  
Lake Bottom

<p>Climate affects the mineralogy and grain size of sediments deposited in lakes. These properties are reflected in the sediment magnetic properties and can be characterized using magnetic methods. As part of the Cadagno-Project, which recovered several gravity and piston cores spanning the entire lake history from the deglacial to the present from the deepest part of permanently stratified Lake Cadagno, which is due to its peculiar water column chemistry considered an early Earth ocean analogue, our study aims to define changes in climate conditions during sedimentation. Here, we present a rock magnetic dataset (low-field magnetic susceptibility and its temperature dependence, anhysteretic and isothermal remanent magnetization (ARM, IRM), acquired in various fields, AF demagnetization, and hysteresis loops) that helps characterize the concentration, mineralogy, and grain size of magnetic carriers, and their variability with depth. Susceptibility, ARM, and IRM were measured on core sediments down to a depth of 886 cm below the lake bottom, providing a high-resolution record of the sedimentary environment of Lake Cadagno over the last 11,000 years. In addition to these depth profiles, detailed rock magnetic experiments were conducted at specific depths. The cores consist of pelagic sediments, flood turbidites, and late glacial sediments. In order to determine the characteristics of the background sedimentation, only turbidite-free intervals were included in this study. The depth profiles of susceptibility, ARM and IRM have approximately similar variations with depth. They show distinct peaks at the upper parts of the pelagic sediments (156-158 cm below the lake bottom,   ̴1280-1320 cal. Yr Bp) and of the late glacial sediments (826-844 cm below the lake bottom), which can be interpreted as increased concentration of ferromagnetic minerals or as a change in the magnetic mineralogy, in addition to decreasing trend in the background. Several intervals within the pelagic sediments are dominated by low-coercivity minerals (<10 mT), while higher coercivity grains (10–100 mT) contribute significantly at (150-170, 418-448 and 719-735 cm below the lake bottom). Magnetic grain size was analyzed using a Day plot, and shows that single domain magnetite dominates at (844 cm) below the lake bottom, indicating the presence of magnetotactic bacteria, which are believed to dwell mainly in the oxic–anoxic interface where chemical gradients are high. These results provide important constraints on the environmental conditions and climate change recorded by the magnetic minerals in Lake Cadagno.</p>

scholarly journals Abiotic landscape and vegetation patterns in the Netherlands during the Weichselian Late Glacial

2000 ◽  
Vol 79 (4) ◽  
pp. 497-509 ◽  
Author(s):  
W.Z. Hoek
Keyword(s):  
The Netherlands ◽  
Soil Formation ◽  
Late Glacial ◽  
The Other ◽  
Vegetation Patterns ◽  
Vegetation Development ◽  
Pollen Diagrams ◽  
Landscape Types ◽  
Geomorphological Processes ◽  
Close Interrelationship

AbstractThe Late Glacial landscape of the Netherlands was a landscape with changing geomorphology and vegetation. Glacial, eolian and fluvial processes in the time before the Late Glacial initially had formed the main landscape types that still existed during the Late Glacial. In these landscape types, geomorphological processes persisted, particularly during intervals when the vegetation cover was discontinuous. Vegetation development initiated soil formation and stabilised the substratum. On the other hand, the abiotic landscape influenced vegetation development, and particularly vegetation patterns.The Late Glacial vegetation patterns, changing in time, have been reconstructed on the basis of a palynological database containing the data from over 250 pollen diagrams from the Netherlands. Patterns of vegetation and abiotic landscape appear to compare to each other in many instances, indicating the close interrelationship between vegetation and the abiotic landscape.

Antiquity of Man at Anaktuvuk Pass, Alaska

1964 ◽  
Vol 29 (4) ◽  
pp. 493-496 ◽  
Author(s):  
Stephen C. Porter
Keyword(s):  
Late Glacial ◽  
Valley Floor ◽  
Archaeological Sites ◽  
Advanced Stage ◽  
Radiocarbon Dates ◽  
Glacial Sediments ◽  
Terminal Moraine ◽  
Probable Time

AbstractGeologic evidence from Anaktuvuk Pass indicates that the latest ice advance during the Itkillik glaciation reached its maximum stand between 8000 and 9000 years ago. Archaeological sites at the pass lie behind a terminal moraine built during this advance and therefore must postdate it. In view of the probable time involved for deglaciation, habitable ice-free areas near the axis of the valley could not have been available for campsites until an advanced stage of ice wastage. Radiocarbon dates indicate that deglaciated areas existed near the present drainage divide as early as 7200 years ago, but prior to that time the valley floor was largely buried under stagnant ice. Although certain archaeological complexes have been interpreted on the basis of typology as evidencing considerable antiquity, the geologic relationships between the sites and radiocarbon-dated, late-glacial sediments places a maximum limiting age of about 7000 years on the oldest cultural materials.

scholarly journals Pore-water controlled grain fracturing as an indicator for subglacial shearing in tills

1997 ◽  
Vol 43 (145) ◽  
pp. 446-454 ◽  
Author(s):  
John F. Hiemstra ◽  
Jaap J. M. Van Der Meer
Keyword(s):  
The Netherlands ◽  
Pore Water ◽  
Genetic Classification ◽  
Glacial Deposits ◽  
Thin Sections ◽  
Glacial Sediments ◽  
Fracturing Process

AbstractGenetic classification of glacial deposits still proves to be highly controversial. In many cases, it remains unclear whether a particular sediment has been sub-glacially deformed. In the present paper it is suggested that micromorphological research is helpful where current techniques fail to lead to unambiguous interpretations. It is argued that the occurrence of fractured grains in glacial sediments is indicative of subglacial shearing and that such grains may be used as diagnostic evidence of glaciotectonism. Deformational mechanisms associated with the fracturing process are outlined and explained, using a series of thin sections from Wijnjewoude, The Netherlands.

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.

Glacial Sediment–Landform Associations and Paleoclimate during the Last Glaciation, Strait of Magellan, Chile

2000 ◽  
Vol 54 (1) ◽  
pp. 13-23 ◽  
Author(s):  
Douglas I. Benn ◽  
C. M. Clapperton
Keyword(s):  
Late Glacial ◽  
Cyclonic Storm ◽  
Glacial Sediments ◽  
Strait Of Magellan ◽  
Models Comparison ◽  
The Strait Of Magellan ◽  
Glacial Time ◽  
The Last Glacial Maximum ◽  
Average Position ◽  
The Last Glacial

Glacial sediments and landforms preserved beside the Strait of Magellan record repeated advances of an outlet of the Patagonian Icefield during and following the last glacial maximum (LGM; ∼25,000–14,000 14C yr B.P.). Ice-marginal landform assemblages consist of thrust moraine complexes, kame and kettle topography, and lateral meltwater channels, very similar to those found at the margins of modern subpolar glaciers. Taken together with other forms of paleoenvironmental evidence, the landform assemblages show that, during the LGM and late-glacial time, permafrost occurred near sea level in southernmost South America. This finding implies that mean annual temperatures were ∼7–8°C lower than at present, somewhat lower than those reconstructed by current glacier–climatic models. Comparison with precipitation–temperature relationships for modern glaciers suggests, in addition, that precipitation levels were lower than today. Reduced glacial-age precipitation may have resulted from a precipitation shadow induced by the Patagonian Icefield, an equatorward migration of the average position of westerly cyclonic storm tracks in the southern midlatitudes, or both these factors.

scholarly journals Late- and Post-glacial sediments in the Randers fjord area. Geochemical, sedimentological, and geoelectric investigations

1976 ◽  
Vol 107 ◽  
pp. 1-124
Author(s):  
Arne Villumsen ◽  
Holger Lykke Andersen
Keyword(s):  
Marine Sediments ◽  
Water Depth ◽  
Groundwater Level ◽  
Bottom Water ◽  
Sedimentary Facies ◽  
Late Glacial ◽  
Supplementary Information ◽  
Specific Resistivity ◽  
Glacial Sediments ◽  
New System

Thickness and distribution of Late- and Post-glacial sediments in an Eastern Jutland valley system have been mapped, and their sedimentogenetic and diagenetic relations have been studied. The chemical and sedimentological methods used are discussed in detail. Post-glacial marine sediments formed in a tidal fjord environment are the most important deposits in the area, and it is shown that river supplies of freshwater control the salinity of the environment and were responsible for the rather high content of allochthonous material in the sediment. The marine sediments rest on Late-glacial sand, whose surface topography indicates that the valleys were formed by subglacial erosion. Local occurrences of dead ice were present at least until the Littorina sea (Atlantic) transgression. Depth conditions for Early Post-glacial peat are used to estimate the groundwater level and the course of the river Gudenå in the Continental Period. Sedimentary facies in the Atlantic Littorina sea are discussed, including salinity, tidal activity, water depth, nutrient conditions, and exchange of stagnant bottom water from the deepest parts of the fjord area. The sequence seems to have been influenced only by minor syndiagenetic and weathering processes.With the intention of providing supplementary information to that obtained from mapping of the Post-glacial sediments of the region 161 electric soundings have been carried out in the Randers fjord area. The specific resistivity of the sediments has been determined and the principle limitations of the methods applied have been investigated. Interpretation of the electric soundings has been done using a new system of computer programs. Maps showing the thickness relationships and variations in specific resistivity in the uppermost, largely Post-glacial deposits in the area have been prepared, and a map showing the location of the surface of the Danian limestone and occurrence of Tertiary clay is also presented.

Notes on late-glacial palynology and geochronology at St. Hilaire, Quebec

1968 ◽  
Vol 5 (2) ◽  
pp. 249-257 ◽  
Author(s):  
J. Terasmae ◽  
P. Lasalle
Keyword(s):  
Late Glacial ◽  
Climatic Fluctuations ◽  
Radiocarbon Dates ◽  
Glacial Sediments ◽  
Cold Episode ◽  
Palynological Study

A palynological study supported by radiocarbon dates of late-glacial sediments at St. Hilaire, Quebec, indicates that the southern part of the St. Lawrence Lowland was deglaciated prior to 12 500 years B.P. The late-glacial episode comprises several climatic fluctuations: a probable early cool interval (northern boreal) more than 12 500 years B.P.; a relatively colder interval (tundra) about 12 500 years B.P., followed by another cool interval from about 12 000 years B.P. to about 10 000 years ago. Another relatively cold episode may have occurred about 11 000 years ago. The new studies extend the previously available palynological record in the St. Lawrence Lowland back in time by about 2000 years and include the Champlain Sea episode.

Sign in / Sign up

Export Citation Format

Share Document