Radiocarbon dating and post-glacial vegetational history: Scaleby Moss

1957 ◽  
Vol 243 (1233) ◽  
pp. 289-289
Keyword(s):  
Radiocarbon Dating ◽  
Late Glacial ◽  
Glacial Period ◽  
Zone Boundary ◽  
Background Rate ◽  
Late Glacial Period ◽  
The North ◽  
Self Consistent ◽  
The North Sea ◽  
Combustion Technique

A proportional gas-counter of about 2 1. volume, within a castle of 5 tons of zinc, enclosing in turn an anticoincidence shield, has been used to make radiocarbon assays of highly purified carbon dioxide at a pressure of 2 atm. A net contemporary count-rate of twenty-seven counts per minute has been secured with a constant background rate of twenty-five. The chief features of this apparatus and of the combustion technique are briefly indicated. The radiocarbon assays have been employed to provide age determinations from a series of peat samples secured from a dry peat-bog at Scaleby Moss, Cumberland. The whole peat sequence has been pollen-analyzed and each radiocarbon sample is very exactly referred to a major zone boundary in a zone sequence which extends from the Late-glacial period continuously through almost the whole of the Post-glacial period. The dates obtained have been based upon an estimated half-life for radiocarbon of 5568 ± 30 years. The errors of determination are of the order (1 standard deviation) of ± 150 years. The results are satisfactorily self-consistent, contiguous samples have closely similar dates, and the whole series of dates follows the stratigraphical sequence. It is shown that at Scaleby Moss the Late-glacial/Post-glacial boundary was about 8300B. C., the Boreal/Atlantic boundary at about 5000 B. C., and the Sub-boreal/Sub-atlantic boundary at about 3000 B. C. The other zone datings conform with this sequence. This evidence goes some way to establish the synchroneity of the major zones on both sides of the North Sea and indicates the suitability of the method for resolving this type of quater­nary historical problem.

Radiocarbon dating and post-glacial vegetational history: Scaleby Moss

1957 ◽  
Vol 147 (928) ◽  
pp. 352-366 ◽  
Keyword(s):  
Radiocarbon Dating ◽  
Late Glacial ◽  
Glacial Period ◽  
Zone Boundary ◽  
Background Rate ◽  
Late Glacial Period ◽  
The North ◽  
Self Consistent ◽  
The North Sea ◽  
Combustion Technique

A proportional gas-counter of about 21. volume, within a castle of 5 tons of zinc, enclosing in turn an anticoincidence shield, has been used to make radiocarbon assays of highly purified carbon dioxide at a pressure of 2 atm. A net contemporary count-rate of 27 counts per minute has been secured with a constant background rate of 25. The chief features of this apparatus and of the combustion technique are briefly indicated. The radiocarbon assays have been employed to provide age determinations from a series of peat samples secured from a dry peat-bog at Scaleby Moss, Cumberland. The whole peat sequence has been pollen-analyzed and each radiocarbon sample is very exactly referred to a major zone boundary in a zone sequence which extends from the Late-glacial period continuously through almost the whole of the Post-glacial period. The dates obtained have been based upon an estimated half-life for radiocarbon of 5568 ± 30 years. The errors of determination are of the order (1 S. D.) of ± 150 years. The results are satisfactorily self-consistent, contiguous samples have closely similar dates, and the whole series of dates follows the stratigraphical sequence. It is shown that at Scaleby Moss the Late-glacial/Post-glacial boundary was about 8300 B. C.; The Boreal/Atlantic boundary at about 5000 B. C., and the Sub-boreal/Sub-atlantic boundary at about 3000 B. C. The other zone datings conform with this sequence. This evidence goes some way to establish the synchroneity of the major zones on both sides of the North Sea and indicates the suitability of the method for resolving this type of Quaternary historical problem.

XIX.—The Late-glacial History of the Highlands and Islands of Scotland

1955 ◽  
Vol 62 (3) ◽  
pp. 769-928 ◽  
Author(s):  
J. K. Charlesworth
Keyword(s):  
Late Glacial ◽  
Glacial Period ◽  
Glacial History ◽  
The West ◽  
Orkney Islands ◽  
Second Stage ◽  
Late Glacial Period ◽  
The North ◽  
Moray Firth ◽  
History Of

SynopsisFrom the abounding moraines, drainage features (fig. 21) and other marginal indications an attempt has been made to reconstruct the successive phases of the ice in its retreat into the corries of the Highlands and Islands (Pl. I). Two late-glacial stages are recognised. During the first, the Highland Glaciation, an ice-margin ran from the Orkney Islands across the mouth of the Moray Firth to the Buchan and out to sea north of Aberdeen. Twelve substages (A–L) of retreat, arbitrarily selected, have been traced through the country, except in the Moraineless West where they are unrepresented.At the maximum of the second stage, the Moraine Glaciation, the ice readvanced to the line stage M (beaded line in Pl. I). The retreat from this line, the inner boundary of the Moraineless West and of the 100-foot raised beach (Pl. I), is divided into nine substages (N–V), based upon a consideration of snowlines. Substage N corresponds to the 50-foot raised beach, substage P to an important readvance.The snowline throughout the late-glacial period ran in the west parallel with the meridians and rose eastwards. The disposition of the snowlines for stage M is given in fig. 22, p. 900.The distribution of the ice in the British Isles during the North British, Highland and Moraine Glaciations is represented in fig. 23, p. 923.

Late-glacial deposits on the chalk of South-East England

1963 ◽  
Vol 246 (730) ◽  
pp. 203-254 ◽  
Keyword(s):  
Late Glacial ◽  
The Arctic ◽  
Glacial Period ◽  
Frozen Ground ◽  
North West ◽  
Late Glacial Period ◽  
The North ◽  
Zone Ii ◽  
South East England ◽  
A Minor

Subaerial deposits of the Late-glacial Period ( ca . 12000 to 8300 B. C.) of the Last Glaciation are described at a number of sites in Kent, Surrey and Sussex. The deposits are primarily stratified chalk muds and fine rubbles, produced by frost-shattering and the release of water from melting snow-fields and from frozen ground. The climatic improvement of zone II, or Allerod Oscillation (10000 to 8800 B. C.), is widely reflected stratigraphically by a rendsina soil, containing fragments of wood charcoal, separating two sheets of chalk muds referred to zones I and III. The age of the soil has been confirmed by radiocarbon dating. It is correlated with the Usselo Layer within the Younger Coversands of the Netherlands. There is evidence from two areas, Folkestone and the Medway Valley, that the climate of south-east England became sufficiently cold during zone III to produce fairly intense frost-heaving (cryoturbation). The deposits contain virtually no pollen, but yield a fauna of land Mollusca. Columns of samples were collected from six sections and the assemblages they yielded are presented in the form of histograms, showing the changing vertical abundance of each species. The fauna is a remarkable mixture of diverse zoogeographical elements; its relations are with the Alpine area rather than with the Arctic. The ecological and climatic significance of the changes in the assemblages is discussed. During zone II, the assemblages increase in variety and certain relatively thermophilous species were able to spread widely, most notably the West European and Alpine snail Abida secale . The climate of zone III was probably more humid than that of zone I, and also less cold. In Sussex, due to the proximity of the open sea to the south-west, the climate of zone I may have been relatively milder than in Kent and Surrey; this is suggested by the appearance of thermophilous species perhaps 1000 years before their general expansion on the North Downs. Evidence is put forward from several sites for a minor climatic oscillation within zone I ; this is equated with the Bolling Oscillation (zone I b ) of north-west Europe. The Late-glacial Period is the last for which there is evidence of active erosion in the Chalk landscape.

Radiocarbon dating of the Late-glacial Period in Britain

1959 ◽  
Vol 150 (939) ◽  
pp. 199-215 ◽  
Keyword(s):  
Radiocarbon Dating ◽  
Late Glacial ◽  
West Germany ◽  
Glacial Period ◽  
Phase Zone ◽  
Depositional Sequence ◽  
Radiocarbon Dates ◽  
North West ◽  
Late Glacial Period ◽  
Ice Retreat

Radiocarbon dating by means of a proportional gas-counter containing carbon dioxide at a pressure of 2 atm has been applied to the dating of deposits from several widely spaced sites in Great Britain. At each of these sites independent investigations of the stratigraphy and plant remains, and particularly systematic pollen analysis, had demonstrated that the deposits were referable to zones I, II and III of the Late-glacial Period. Organic samples were taken from carefully defined horizons at these sites. The datings are remarkably self-consistent and indicate that the zones as previously defined are synchronous throughout this country. It seems that the upper and lower boundaries for the cool temperate Allerod phase (zone II) fall approximately at 8800 and 10000 years B. C., whilst the succeeding colder phase (zone III) lasted until about 8300 B. C., approximately the time at which the ice-retreat began from the line of the Highland Re-advance in Scotland and from the Central Swedish moraines and Norwegian Raa in Scandinavia, as already suggested by varve-chronology. This is the Late-glacial/Post-glacial boundary. Brief comparison of published radiocarbon dates of the Late­ glacial zones in Denmark, north-west Germany and Holland indicate that these also are synchronous with one another and with the zones recognized in Britain. Attention is directed to five substantial sources of error to which datings of this kind are liable: contamination of the original samples by derived coal, the use of organic muds in which carbon has originated from photosynthesis of submerged plants in hard waters, failure to to observe gaps in the depositional sequence, the so-called ‘Suess’ effect, and the seepage of organic material from above into older layers.

Progressive glacial retreat in the Southern Altiplano (Uturuncu volcano, 22°S) between 65 and 14 ka constrained by cosmogenic 3He dating

2014 ◽  
Vol 82 (1) ◽  
pp. 209-221 ◽  
Author(s):  
Pierre-Henri Blard ◽  
Jérôme Lave ◽  
Kenneth A. Farley ◽  
Victor Ramirez ◽  
Nestor Jimenez ◽  
...  
Keyword(s):  
Late Pleistocene ◽  
Late Glacial ◽  
Glacial Period ◽  
Tropical Andes ◽  
Equilibrium Line Altitude ◽  
Glacial Retreat ◽  
Late Glacial Period ◽  
Cold Episode ◽  
Glacial Landforms ◽  
Exposure Ages

AbstractThis work presents the first reconstruction of late Pleistocene glacier fluctuations on Uturuncu volcano, in the Southern Tropical Andes. Cosmogenic 3He dating of glacial landforms provides constraints on ancient glacier position between 65 and 14 ka. Despite important scatter in the exposure ages on the oldest moraines, probably resulting from pre-exposure, these 3He data constrain the timing of the moraine deposits and subsequent glacier recessions: the Uturuncu glacier may have reached its maximum extent much before the global LGM, maybe as early as 65 ka, with an equilibrium line altitude (ELA) at 5280 m. Then, the glacier remained close to its maximum position, with a main stillstand identified around 40 ka, and another one between 35 and 17 ka, followed by a limited recession at 17 ka. Then, another glacial stillstand is identified upstream during the late glacial period, probably between 16 and 14 ka, with an ELA standing at 5350 m. This stillstand is synchronous with the paleolake Tauca highstand. This result indicates that this regionally wet and cold episode, during the Heinrich 1 event, also impacted the Southern Altiplano. The ELA rose above 5450 m after 14 ka, synchronously with the Bolling–Allerod.

scholarly journals Surface profiles and basal shear stresses of outlet glaciers from a Late-glacial mountain ice field in western Scotland

1991 ◽  
Vol 37 (125) ◽  
pp. 77-88 ◽  
Author(s):  
Peter W. Thorp
Keyword(s):  
Late Glacial ◽  
Shear Stresses ◽  
Glacial Period ◽  
Late Glacial Period ◽  
Bedrock Topography ◽  
Pore Water Pressures ◽  
Basal Sliding ◽  
Ice Field ◽  
Surface Profiles ◽  
Basal Shear

Abstract Surface and basal long profiles are reconstructed for 13 outlet glaciers that drained ice from a large ice field (80 km by 120 km) that formed in the western Grampians of Scotland during part of the Late-glacial period (c, 14000–10000years BP). Basal shear stresses are calculated at 5 km intervals along the central flowlines of the reconstructed outlet glaciers. Individual basal shear stresses for the outlet glaciers range from 10 to 204 kPa. Variations in calculated basal shear stresses within and between the glaciers are mainly explained by differences in bedrock topography, extending and compressional flow, and by differences in basal boundary conditions. Low basal shear stresses (<53kPa) calculated for the terminal zones of Creran, Menteith and Lomond glaciers are partly explained by the overriding of glaciomarine clays with inferred high pore-water pressures and a low yield strength that may have led to rapid basal sliding and thinning of the ice lobes.

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