scholarly journals Southward Displacement of the Distribution of Glaciation During the Three Maxima of the Last Ice Age

1977 ◽  
Vol 18 (79) ◽  
pp. 305-308
Author(s):  
Nils-Axel Mörner
Keyword(s):  
Deep Sea ◽  
Ice Sheets ◽  
General Rule ◽  
Ice Age ◽  
Pleistocene Glaciations ◽  
The North ◽  
Climatic Control ◽  
Last Ice Age ◽  
North And South

AbstractThe Laurentide and Fennoscandian ice sheets had three major glaciation maxima during the Last Ice Age. All data from the southern margins of the ice sheets indicate that these maxima, as well as minor fluctuations, were synchronous. The same synchroneity is supposed to apply also for correlations between fluctuations on the north and south margins, which reveal a continuously southward displacement of the distribution of glaciation during the Last Ice Age. This southward displacement explains the saw-tooth pattern of 18O records from deep-sea cores in which the first glaciation maximum is under-represented due to its distribution more towards the north. The synchroneity is consistent with a global climatic control of the stadial/interstadial changes and with the recorded global eustatic changes. The southward displacement of glaciation seems to be a general rule also applicable to earlier Pleistocene glaciations.

scholarly journals Southward Displacement of the Distribution of Glaciation During the Three Maxima of the Last Ice Age

1977 ◽  
Vol 18 (79) ◽  
pp. 305-308 ◽  
Author(s):  
Nils-Axel Mörner
Keyword(s):  
Deep Sea ◽  
Ice Sheets ◽  
General Rule ◽  
Ice Age ◽  
Pleistocene Glaciations ◽  
The North ◽  
Climatic Control ◽  
Last Ice Age ◽  
North And South

Abstract The Laurentide and Fennoscandian ice sheets had three major glaciation maxima during the Last Ice Age. All data from the southern margins of the ice sheets indicate that these maxima, as well as minor fluctuations, were synchronous. The same synchroneity is supposed to apply also for correlations between fluctuations on the north and south margins, which reveal a continuously southward displacement of the distribution of glaciation during the Last Ice Age. This southward displacement explains the saw-tooth pattern of 18O records from deep-sea cores in which the first glaciation maximum is under-represented due to its distribution more towards the north. The synchroneity is consistent with a global climatic control of the stadial/interstadial changes and with the recorded global eustatic changes. The southward displacement of glaciation seems to be a general rule also applicable to earlier Pleistocene glaciations.

scholarly journals Paleogroundwater in the Moutere Gravel Aquifers Near Nelson, New Zealand

Radiocarbon ◽  
2004 ◽  
Vol 46 (2) ◽  
pp. 517-529 ◽  
Author(s):  
Michael K Stewart ◽  
Joseph T Thomas ◽  
Margaret Norris ◽  
Vanessa Trompetter
Keyword(s):  
New Zealand ◽  
Large Body ◽  
Ice Age ◽  
Deep Groundwater ◽  
Sea Levels ◽  
The North ◽  
Discharge Water ◽  
Wide System ◽  
Last Ice Age ◽  
North And South

Radiocarbon, 18O, and chemical concentrations have been used to identify groundwater recharged during the last ice age near Nelson, New Zealand. Moutere Gravel underlies most of the Moutere Depression, a 30-km-wide system of valleys filled with Plio-Pleistocene gravel. The depression extends northwards into Tasman Bay, which was above sea level when the North and South Islands of New Zealand were connected during the last glaciation. The aquifers are tapped by bores up to 500 m deep. Shallow bores (50–100 m) tap “pre-industrial” Holocene water (termed the “modern” component) with 14C concentrations of 90 ± 10 percent modern carbon (pMC) and δ18O values of −6.8 ± 0.4, as expected for present-day precipitation. Deeper bores discharge water with lower 14C concentrations and more negative 18O values resulting from input of much older water from depth. The deep end-member of the mixing trend is identified as paleowater (termed the “glacial” component) with 14C concentration close to 0 pMC and more negative 18O values (-7.6). Mixing of the modern and glacial components gives rise to the variations observed in the 14C, 18O, and chemical concentrations of the waters. Identification of the deep groundwater as glacial water suggests that there may be a large body of such water onshore and offshore at deep levels. More generally, the influence of changing sea levels in the recent past (geologically speaking) on the disposition of groundwaters in coastal areas of New Zealand may have been far greater than we have previously realized.

Cave Archaeology and Palaeontology in the Creswell Region

2007 ◽  
Author(s):  
Andrew T. Chamberlain
Keyword(s):  
Ice Age ◽  
Upper Permian ◽  
The North ◽  
Cave Archaeology ◽  
History Of ◽  
The North Sea ◽  
Last Ice Age ◽  
North And South ◽  
Heritage Area ◽  
Carboniferous Limestone

The aim of this chapter is to situate the unique discoveries of cave art at the Creswell Crags caves in the context of what is known of the cave archaeology and palaeontology of the caves of the southern Magnesian Limestone outcrop. The long history of archaeological research at Creswell Crags and the spectacular discoveries that continue to be made in the Creswell caves have tended to overshadow the widespread though less prominent distribution of cave archaeological sites along the limestone outcrop to the north and south of Creswell, a region known as the Creswell Crags Limestone Heritage Area (Mills 2001). Recent audits of the archaeology of the region have drawn attention to the large number of cave sites within the Limestone Heritage Area as well as the considerable potential that these sites have for further research into the history of Ice Age people and their environments (Mills 2001; Davies et al. 2004).While the focus of this chapter is on the Pleistocene deposits and Palaeolithic artefacts that have been preserved in the region’s caves, fissures, and rock shelters, these sites were used throughout prehistory by humans and animals and they contain much important cultural and environmental evidence for these later time periods after the end of the last Ice Age. Creswell Crags is located in the southern part of the Magnesian Limestone, a geological term for deposits of Upper Permian age that includes a series of formations of well-bedded oolitic to dolomitic limestones. The Magnesian Limestone forms a narrow north–south oriented outcrop that runs from near Nottingham in the south to the North Sea coast near Tynemouth in the north (Fig. 6.1). About 30 km to the west of the southern part of the Magnesian Limestone is the older Carboniferous Limestone outcrop of the White Peak, which, like the Magnesian Limestone, contains many archaeological caves. The southern part of the Magnesian Limestone outcrop, between Doncaster and Mansfield, is cut through by a series of vales and gorges which expose caves, fissures, and rockshelters along the cliff lines.

Paleoecology and Late Quaternary Environments of the Colorado Rockies

2001 ◽  
Author(s):  
Scott A. Elias
Keyword(s):  
North America ◽  
Late Quaternary ◽  
Ice Sheets ◽  
Ice Sheet ◽  
Rocky Mountain ◽  
Mountain Region ◽  
Ice Age ◽  
Rocky Mountain Region ◽  
Last Ice Age ◽  
Teton Range

Present-day environments cannot be completely understood without knowledge of their history since the last ice age. Paleoecological studies show that the modern ecosystems did not spring full-blown onto the Rocky Mountain region within the last few centuries. Rather, they are the product of a massive reshuffling of species that was brought about by the last ice age and indeed continues to this day. Chronologically, this chapter covers the late Quaternary Period: the last 25,000 years. During this interval, ice sheets advanced southward, covering Canada and much of the northern tier of states in the United States. Glaciers crept down from mountaintops to fill high valleys in the Rockies and Sierras. The late Quaternary interval is important because it bridges the gap between the ice-age world and modern environments and biota. It was a time of great change, in both physical environments and biological communities. The Wisconsin Glaciation is called the Pinedale Glaciation in the Rocky Mountain region (after terminal moraines near the town of Pinedale, Wyoming; see chapter 4). The Pinedale Glaciation began after the last (Sangamon) Interglaciation, perhaps 110,000 radiocarbon years before present (yr BP), and included at least two major ice advances and retreats. These glacial events took different forms in different regions. The Laurentide Ice Sheet covered much of northeastern and north-central North America, and the Cordilleran Ice Sheet covered much of northwestern North America. The two ice sheets covered more than 16 million km2 and contained one third of all the ice in the world’s glaciers during this period. The history of glaciation is not as well resolved for the Colorado Front Range region as it is for regions farther north. For instance, although a chronology of three separate ice advances has been established for the Teton Range during Pinedale times, in northern Colorado we know only that there were earlier and later Pinedale ice advances. We do not know when the earlier advance (or multiple advances) took place. However, based on geologic evidence (Madole and Shroba 1979), the early Pinedale glaciation was more extensive than the late Pinedale was.

scholarly journals The Atmosphere’s Response to the Ice Sheets of the Last Glacial Maximum

1990 ◽  
Vol 14 ◽  
pp. 32-38 ◽  
Author(s):  
Kerry H. Cook
Keyword(s):  
Atlantic Ocean ◽  
North Atlantic ◽  
North Atlantic Ocean ◽  
Ice Sheets ◽  
Ice Sheet ◽  
Ice Age ◽  
Laurentide Ice Sheet ◽  
Stationary Waves ◽  
The North ◽  
The Last Glacial

This paper discusses some modeling results that indicate how the atmospheric response to the topography of the continental ice of the Last Glacial Maximum (LGM) may be related to the cold North Atlantic Ocean of that time. Broccoli and Manabe (1987) used a three-dimensional general circulation model (GCM) of the atmosphere coupled with a fixed-depth, static ocean mixed-layer model with ice-age boundary conditions to investigate the individual influences of the CLIMAP ice sheets, snow-free land albedos, and reduced atmospheric CO2 concentrations. They found that the ice sheets are the most influential of the ice-age boundary conditions in modifying the northern hemisphere climate, and that the presence of continental ice sheets alone leads to cooling over the North Atlantic Ocean. One approach for extending these GCM results is to consider the stationary waves generated by the ice sheets. Cook and Held (1988) showed that a linearized, steady-state, primitive equation model can give a reasonable simulation of the GCM’s stationary waves forced by the Laurentide ice sheet. The linear model analysis suggests that the mechanical effect of the changed slope of the surface, and not changes in the diabatic heating (e.g. the high surface albedos) or time-dependent transports that necessarily accompany the ice sheet in the GCM, is largely responsible for the ice sheet’s influence. To obtain the ice-age stationary-wave simulation, the linear model must be linearized about the zonal mean fields from the GCM’s ice-age climate. This is the case because the proximity of the cold polar air to the region of adiabatic heating on the downslope of the Laurentide ice sheet is an important factor in determining the stationary waves. During the ice age, cold air can be transported southward to balance this downslope heating by small perturbations in the meridional wind, consistent with linear theory. Since the meridional temperature gradient is more closely related to the surface albedo (ice extent) than to the ice volume, this suggests a mechanism by which changes in the stationary waves and, therefore, their cooling influence at low levels over the North Atlantic Ocean, can occur on time scales faster than those associated with large changes in continental ice volume.

Ice cores and climatic change

1977 ◽  
Vol 280 (972) ◽  
pp. 143-168 ◽  
Keyword(s):  
Ice Sheets ◽  
Ice Cores ◽  
Ice Age ◽  
Isotopic Ratios ◽  
Temperature Profiles ◽  
Physical Processes ◽  
Similar Relation ◽  
Stable Isotopic ◽  
Last Ice Age ◽  
Glacial Periods

The paper deals primarily with the use of stable isotopic ratios to determine the former climate of ice sheets. Studies of temperature profiles throughout ice sheets have shown that for at least several thousand years, changes of isotopic δ ratios have been proportional to changes of surface temperatures; this relationship is discussed in terms of the physical processes involved. It is considered reasonable to use a similar relation for earlier periods in Antarctica, but in Greenland the relation may have varied with time. When determining past climates from the isotopic record, allowances have to be made for changes in the flow and thickness of ice sheets during major glacial periods. These factors are considered in relation to major ice cores from Vostok and Byrd stations in Antarctica and from Camp Century in Greenland. Vostok is the simplest case glaciologically, Camp Century the most complex. On purely glaciological grounds it appears that the ice age gave way to present-day climates some 10 000 ± 1000 a B.P., the coldest period being 20 000 + 3000 a B.P., when the climate in Antarctica was 6-8 °C colder than at present. Glaciological data suggest a duration of 50 000 to 100 000 years for the last ice age. Before this period, climates in Greenland and Antarctica appear to have been around 2-3 °C warmer than at present.

Deep water formation in the North Atlantic Ocean during the last ice age

Nature ◽  
1980 ◽  
Vol 286 (5772) ◽  
pp. 479-482 ◽  
Author(s):  
Jean-Claude Duplessy ◽  
J. Moyes ◽  
C. Pujol
Keyword(s):  
Atlantic Ocean ◽  
North Atlantic ◽  
Deep Water ◽  
North Atlantic Ocean ◽  
Ice Age ◽  
Deep Water Formation ◽  
The North ◽  
Water Formation ◽  
Last Ice Age ◽  
The North Atlantic

scholarly journals XXVI. On the Rhizopodal Fauna of the Deep Sea

1870 ◽  
Vol 18 (114-122) ◽  
pp. 59-62 ◽  
Keyword(s):  
North Atlantic ◽  
Deep Sea ◽  
North Atlantic Ocean ◽  
General Rule ◽  
Equatorial Region ◽  
The Arctic ◽  
Shallow Waters ◽  
Arctic Seas ◽  
The North ◽  
And Diffusion

The Author commences by referring to the knowledge of the Rhizopodal Fauna of the Deep Sea which has been gradually acquired by the examination of specimens of the bottom brought up by the Sounding-apparatus; and states that whilst this method of investigation has made known the vast extent and diffusion of Foramimferal life at great depths,-especially in the case of Globigerina-mud , which has been proved to cover a large part of the bottom of the North Atlantic Ocean,—it has not added any new Generic types to those discoverable in comparatively shallow waters. With the exception of a few forms, which, like find their most congenial home, and attain their greatest development, at great depths, the general rule has seemed to be that Foramimfera are progressively dwarfed in proportion to increase of depth, as they are y a change from a warmer to a colder climate; those which are brought up from great depths in the Equatorial region bearing a much stronger resemblance to those of the colder-temperate, or even of the Arctic seas, than to the littoral forms of their own region.

A Remarkable Quartzite Implement

1932 ◽  
Vol 6 (4) ◽  
pp. 304-305
Author(s):  
Bertram Brotherton ◽  
J. Reid Moir
Keyword(s):  
Ice Sheets ◽  
Igneous Rocks ◽  
Ice Age ◽  
Vein Quartz ◽  
Surface Level ◽  
The North ◽  
Gravel Pit ◽  
Marine Current

The gravel-pit in which the implement was found in November, 1929, is known as the Bilford Pit, and is situated about a mile due east of the river Severn, in the Bilford Road, and a mile and a half due north from the centre of Worcester City. The surface level is 100 feet O.D., and the pit is owned and worked by the Worcester Corporation.The area in the immediate vicinity of Worcester could not have been exempt from some of the effects of the abnormal climate that prevailed over the British Islands during the Ice Age, yet we have at present no clear evidence of an invasion of the district by ice-sheets. The drift deposits around Worcester comprise a great variety of pebbles, beds of sand, and a few boulders. The pebbles are similar to those obtained from the Permian and Bunter conglomerates, and the pebble-beds of the Lickey and Clent district (about sixteen miles to the north of Worcester). They include yellow, brown, and liver-coloured quartzites, vein quartz, sandstone, chert, limestone, slate and various igneous rocks.The occurence of marine shells, Cretaceous flints, Liassic fossils, and other drift materials in the gravels extending from Cheshire to Gloucestershire, led Murchison to believe they were laid down by a marine current flowing from the north. Few geologists now accept this explanation.

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