Radiocarbon Dates related to the Scottish Late-Glacial Sea in the Firth of Clyde

Nature ◽  
1970 ◽  
Vol 227 (5257) ◽  
pp. 480-482 ◽  
Author(s):  
W. W. BISHOP ◽  
J. H. DICKSON
2002 ◽  
Vol 51 (1) ◽  
pp. 107-111 ◽  
Author(s):  
Randall F. Miller

Abstract Walrus fossils are occasionally recovered during scallop dragging in the Bay of Fundy and from sand and gravel deposits along the coastline of New Brunswick in eastern Canada. Six new fossils and four new AMS radiocarbon dates significantly increase the information concerning late-glacial to postglacial walrus in New Brunswick. Dates range from about 12 800 BP to 2 900 BP, almost half falling between 9 000 and 10 000 BP. Temporal distribution of walrus, compared to estimates of past summer sea surface temperature, suggest that in the Bay of Fundy walrus occurred in waters ranging from 12 to 15° C.


1996 ◽  
Vol 33 (11) ◽  
pp. 1499-1510 ◽  
Author(s):  
William F. Manley

New georaorphic, sedimentologic, and chronologic data are used to reconstruct late Quaternary ice-sheet flow patterns, deglaciation, and isostatic uplift along the largest marine trough connecting the Laurentide Ice Sheet with the North Atlantic Ocean. The Lake Harbour region was targeted for study given its potential to record flow from several ice-dispersal centers. Striations and sediment provenance indicators define flow patterns. Thirty-four radiocarbon dates constrain a chronology of events. Centuries or millennia(?) before deglaciation, a southeast-flowing ice stream impinged on southernmost Big Island, as recorded by a single striation site and delimited in extent by geomorphic evidence of cold-based ice. During the Cockburn Substagc (9000–8000 BP), the region was scoured by southward to southwestward flow from an ice cap on Meta Incognita Peninsula, as recorded by 60 striation sites along 200 km of coastline. Carbonate erratics are uncommon in till above the marine limit. Where present, they suggest that southward flow reworked older drift. At about 8200 BP, the area was dcglaciated, and the marine limit was established at elevations of 67–141 m above high tide. Iceberg calving and sediment discharge from an ice margin in Ungava Bay, Hudson Bay, or Foxe Basin then blanketed the area with limestone-rich glaciomarinc sediment. Afterward, the region experienced slow but sustained emergence. The data revise the maximum lateral extent of a Late Wisconsinan ice stream in Hudson Strait and emphasize the extent of a late-glacial ice cap on western Meta Incognita Peninsula.


Radiocarbon ◽  
2004 ◽  
Vol 46 (2) ◽  
pp. 933-941 ◽  
Author(s):  
Irina P Panyushkina ◽  
Steven W Leavitt ◽  
Alex Wiedenhoeft ◽  
Sarah Noggle ◽  
Brandon Curry ◽  
...  

The abrupt millennial-scale changes associated with the Younger Dryas (YD) event (“chronozone”) near the dawn of the Holocene are at least hemispheric, if not global, in extent. Evidence for the YD cold excursion is abundant in Europe but fairly meager in central North America. We are engaged in an investigation of high-resolution environmental changes in mid-North America over several millennia (about 10,000 to 14,000 BP) during the Late Glacial–Early Holocene transition, including the YD interval. Several sites containing logs or stumps have been identified and we are in the process of initial sampling or re-sampling them for this project. Here, we report on a site in central Illinois containing a deposit of logs initially thought to be of YD age preserved in alluvial sands. The assemblage of wood represents hardwood (angiosperm) trees, and the ring-width characteristics are favorable to developing formal tree-ring chronologies. However, 4 new radiocarbon dates indicate deposition of wood may have taken place over at least 8000 14C yr (6000–14,000 BP). This complicates the effort to develop a single floating chronology of several hundred years at this site, but it may provide wood from a restricted region over a long period of time from which to develop a sequence of floating chronologies, the timing of deposition and preservation of which could be related to paleoclimatic events and conditions.


1989 ◽  
Vol 31 (3) ◽  
pp. 396-406 ◽  
Author(s):  
Calvin J. Heusser

AbstractVegetation and climate over approximately the past 13,000 yr are reconstructed from fossil pollen in a 9.4-m mire section at Caleta Róbalo on Beagle Channel, Isla Navarino (54°56′S, 67°38′W), southern Tierra del Fuego. Fifty surface samples reflecting modern pollen dispersal serve to interpret the record. Chronologically controlled by nine radiocarbon dates, fossil pollen assemblages are: Empetrum-Gramineae-Gunnera-Tubuliflorae (zone 3b, 13,000–11,850 yr B.P.), Gramineae-Empetrum-assorted minor taxa (zone 3a, 11,850-10,000 yr B.P.), Nothofagus-Gramineae-Tubuliflorae-Polypodiaceae (zone 2, 10,000–5000 yr B.P.), Nothofagus-Empetrum (zone 1b, 5000-3000 yr B.P.), and Empetrum-Nothofagus (zone 1a, 3000-0 yr B.P.). Assemblages show tundra under a cold, dry climate (zone 3), followed by open woodland (zone 2), as conditions became warmer and less dry, and later, with greater humidity and lower temperatures, by closed forest and the spread of mires (zone 1). Comparisons drawn with records from Antarctica, New Zealand, Tasmania, and the subantarctic islands demonstrate broadly uniform conditions in the circumpolar Southern Hemisphere. The influences of continental and maritime antarctic air masses were apparently considerable in Tierra del Fuego during cold late-glacial time, whereas Holocene climate was largely regulated by interplay between maritime polar and maritime tropical air.


Radiocarbon ◽  
2004 ◽  
Vol 46 (2) ◽  
pp. 733-744 ◽  
Author(s):  
Danuta J Michczyńska ◽  
Anna Pazdur

We report on a statistical analysis of a large set of radiocarbon dates for reconstruction of paleoclimate. Probability density functions were constructed by summing the probability distributions of individual 14C dates. Our analysis was based on 2 assumptions: 1) The amount of organic matter in sediments depends on paleogeographical conditions; 2) The number of 14C-dated samples is proportional to the amount of organic matter deposited in sediments in the examined time intervals. We quantified how many dates are required to give statistically reliable results. As an example, 785 peat dates from Poland were selected. The dates encompassed the Holocene and Late Glacial period. All dates came from the Gliwice Radiocarbon Laboratory. Results were compared with other paleoenvironmental records. Detailed analysis of the frequency distributions showed that preferential sampling plays an important part in the shape determination. The general rule to take samples from locations where visible changes of sedimentation are apparent (e.g. from the top and the bottom of the peat layer) results in narrow peaks in the probability density function near the limits of the Holocene subdivision.


1964 ◽  
Vol 29 (4) ◽  
pp. 493-496 ◽  
Author(s):  
Stephen C. Porter

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.


1984 ◽  
Vol 21 (3) ◽  
pp. 275-285 ◽  
Author(s):  
H.E. Wright

Small ice fields on the western cordillera northeast of Lima were expanded to three times their present size in the recent past, and the regional snow line was probably about 100 m lower than it is today. Outwash from the expanded glaciers formed deltas of silt in valley-bottom lakes. When the ice lobes retreated, the reduced outwash was trapped behind recessional moraines, and the clear meltwater infiltrated into the limestone bedrock and emerged at the heads of the deltas in spring pools. The delta surfaces then became covered with peat, and radiocarbon dates for the base of the peat (1100 ± 70 and 430 ± 70 yr B.P. for two different deltas) indicate that the maximum ice advance was older than those dates and, thus, older than the Little Ice Age of many north-temperate regions. Much older moraines date from expansion of the same local summit glaciers to even lower levels in the main valleys, which had previously been inundated by the cordilleran ice field. The cordilleran deglaciation and this expansion of local glaciers probably occurred between 12,000 and 10,000 yr ago, on the basis of slightly contradictory radiocarbon dates.


2020 ◽  
Vol 2 (2) ◽  
pp. 66-78
Author(s):  
Henny Piezonka ◽  

The earliest ceramic vessels of the world have been produced in southern China by Late Glacial hunter-gatherers in the remote times around 18,000 calBC. Over the following millennia the new technology became known among forager communities in the Russian Amur region, in Japan, Korea, Transbaikalia and ultimately appeared also in the Urals and in eastern and northern central Europe. Contrary to common views of pottery as part of the “Neolithic package”, the Eurasian hunter-gatherer ceramic tradition is an innovation that developed completely independent of other Neolithic traits such as agriculture, animal husbandry and sedentary lifestyle. The paper explores the chronological sequence of the appearance of hunter-gatherer ceramic vessel production on the basis of radiocarbon dates in northern Eurasia from the Pacific coast to the Baltic and outlines promising methodological approaches that currently play a role in researching this much-discussed topic.


1968 ◽  
Vol 5 (2) ◽  
pp. 249-257 ◽  
Author(s):  
J. Terasmae ◽  
P. Lasalle

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.


1997 ◽  
Vol 47 (1) ◽  
pp. 37-44 ◽  
Author(s):  
Celina Campbell ◽  
Ian A. Campbell

AbstractCalibration of radiocarbon dates of postglacial geomorphic events in southeastern Alberta, Canada, reveals a strong association between type of geomorphic event and seasonality of insolation. The late glacial and postglacial periods can be divided into four major episodes: glaciation, ca. >20,000 cal yr B.P.; deglaciation, ca. 20,000–12,000 cal yr B.P.; landscape stability, ca. 12,000–10,000 cal yr B.P.; and landscape instability, ca. 10,000–0 cal yr B.P. This indicates that there was significantly more time than previously thought (12,000–13,000 yr) for postglacial processes. Glaciation, deglaciation, maximum landscape stability (indicating maximum aridity), and landscape instability did not lag behind minimum, increasing, maximum, and decreasing seasonality of insolation, respectively.


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