Comments on the Meadowcroft Rockshelter Radiocarbon Chronology and the Recognition of Coal Contaminants

1992 ◽  
Vol 57 (2) ◽  
pp. 321-326 ◽  
Author(s):  
Kenneth B. Tankersley ◽  
Cheryl Ann Munson
Keyword(s):  
North America ◽  
Comparative Data ◽  
Human Occupation ◽  
Radiocarbon Dates ◽  
Carbon Contamination ◽  
Radiocarbon Chronology ◽  
Important Site

Early 14C dates from Meadowcroft Rockshelter have engendered debate on the antiquity of human occupation in North America. Although the investigators of this important site conclude that particulate and nonparticulate contamination have not affected the radiocarbon dates, several points of confusion remain in regard to the question of coal contamination. We clarify these issues, provide comparative data from other sites, and recommend specific tests that are necessary to negate or support the issue of "dead carbon" contamination of radiocarbon samples.

Too Little, Too Late? The Radiocarbon Chronology of Alaska and the Peopling of the New World

2006 ◽  
Vol 71 (4) ◽  
pp. 595-620 ◽  
Author(s):  
Michael R. Bever
Keyword(s):  
Native Americans ◽  
Late Pleistocene ◽  
New World ◽  
Archaeological Record ◽  
Human Occupation ◽  
Radiocarbon Dates ◽  
Point Of Entry ◽  
Central Asian ◽  
Terminal Pleistocene ◽  
Radiocarbon Chronology

Alaska is commonly viewed as a gateway between the Old and New Worlds, and as such, figures prominently in most models of the peopling of the New World. With a growing number of archaeological sites dating to the terminal Pleistocene, Alaska might be expected to provide direct evidence bearing on the colonization of the Americas. Based on 27 site components with 114 radiocarbon dates, this paper discusses the archaeological record of late Pleistocene Alaska, organized around the characteristics and chronology of three complexes: the microblade-bearing Denali complex, the Nenana complex, and the Mesa complex. This paper shows that the archaeological record of late Pleistocene Alaska is quite diverse, and not lacking in controversy and conflicting interpretations. In addition, this period of archaeological diversity coincides with the Younger Dryas climatic event. However, none of the reliably dated sites is older than the earliest evidence of human occupation further south in the Americas. Despite this, evidence from DNA studies points strongly to a north-central Asian homeland for Native Americans, upholding Alaska as the point of entry into the New World. Suggestions are offered, then, as to why the Alaskan record remains silent about the initial peopling of the New World.

An Analysis of the Chronology of Late Pleistocene Mammalian Extinctions in North America

1987 ◽  
Vol 28 (2) ◽  
pp. 281-289 ◽  
Author(s):  
Donald K. Grayson
Keyword(s):  
North America ◽  
Late Pleistocene ◽  
Radiocarbon Dates ◽  
Radiocarbon Chronology ◽  
Population Numbers

AbstractSome 35 genera of mammals became extinct in North America as the Pleistocene came to an end. Current attempts to explain those extinctions generally assume that all of the losses took place between 12,000 and 10,000 yr B.P., even though 13 of the 35 genera lack radiocarbon dates of reasonable validity that would place them in this 2000-yr period. Analyses of the structure of the radiocarbon chronology available for the extinct taxa suggest that some may lack terminal Wisconsin dates simply because they are so poorly represented in the paleontological record. These analyses also suggest, however, that the population numbers of many genera that became extinct toward the end of the Pleistocene may have significantly dwindled by 12,000 yr B.P., and that many of the genera that have yet to be dated to terminal Wisconsin times may not have survived beyond 12,000 yr B.P. If this is the case, current explanations of the extinctions are in need of extensive modification.

scholarly journals Direct dating reveals the early history of opium poppy in western Europe

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Aurélie Salavert ◽  
Antoine Zazzo ◽  
Lucie Martin ◽  
Ferran Antolín ◽  
Caroline Gauthier ◽  
...  
Keyword(s):  
Western Europe ◽  
Western Alps ◽  
Western Mediterranean ◽  
Opium Poppy ◽  
Radiocarbon Dates ◽  
Macrobotanical Remains ◽  
History Of ◽  
Temperate Europe ◽  
Radiocarbon Chronology ◽  
Botanical Remains

AbstractThis paper aims to define the first chrono-cultural framework on the domestication and early diffusion of the opium poppy using small-sized botanical remains from archaeological sites, opening the way to directly date minute short-lived botanical samples. We produced the initial set of radiocarbon dates directly from the opium poppy remains of eleven Neolithic sites (5900–3500 cal BCE) in the central and western Mediterranean, northwestern temperate Europe, and the western Alps. When possible, we also dated the macrobotanical remains originating from the same sediment sample. In total, 22 samples were taken into account, including 12 dates directly obtained from opium poppy remains. The radiocarbon chronology ranges from 5622 to 4050 cal BCE. The results show that opium poppy is present from at least the middle of the sixth millennium in the Mediterranean, where it possibly grew naturally and was cultivated by pioneer Neolithic communities. Its dispersal outside of its native area was early, being found west of the Rhine in 5300–5200 cal BCE. It was introduced to the western Alps around 5000–4800 cal BCE, becoming widespread from the second half of the fifth millennium. This research evidences different rhythms in the introduction of opium poppy in western Europe.

Paleoenvironmental analysis of wet meadow in the Deseado Massif: Implications for the Holocene occupation of Argentinian Patagonia

The Holocene ◽  
2021 ◽  
pp. 095968362110259
Author(s):  
Bruno Mosquera ◽  
María V Mancini
Keyword(s):  
Environmental Changes ◽  
Low Energy ◽  
Semiarid Region ◽  
Human Occupation ◽  
Wet Meadow ◽  
Radiocarbon Dates ◽  
Sedimentation Environment ◽  
Dry Conditions ◽  
Paleoenvironmental Analysis ◽  
Deseado Massif

Paleoenvironmental data from wet-meadow environments in the arid-semiarid region of Patagonia are still incipient and the paleoenvironmental records came from pollen sequences of caves and rockshelters. The main reasons to study wetland records are their undisturbed (by humans) sedimentologic continuity, in contrast to deposits in rock shelters and caves; and their regional presentation of environmental changes that can be compared to archeological data. The aim of this paper is to evaluate the past hydrological dynamic of a wet-meadow from Deseado Massif and its relationship with the human occupation. For this purpose, we present the results of the sediment and pollen analysis of Mallín La Primavera wet-meadow that provide a sequence starting in the mid-Holocene. The results indicate a lower water table in the mallín prior to 6900 cal yr BP. Sediment analysis indicates low energy sedimentation environment with flood events and very low energy streams. Human occupational data show chronological discontinuities in mid-Holocene in several regions of Patagonia and the southern cone. In the studied region, two chronological hiatuses (7828–6434 cal yr BP and 3005–2710 cal yr BP) where recognized that appear to correlate with shrub steppes, indicating dry conditions. These conditions may explain the lack of archeological radiocarbon dates in the area during this period. The integration of sediment and pollen results from the Deseado Massif indicates dry and windy conditions for the middle Holocene. The lack of archeological radiocarbon dates would have been influenced by the loss of moisture in water sources such as springs and their associated wet meadows ( mallines).

Bridge River tephra: revised distribution and significance for detecting old carbon errors in radiocarbon dates of limnic sediments in southern British Columbia

1980 ◽  
Vol 17 (11) ◽  
pp. 1454-1461 ◽  
Author(s):  
Rolf W. Mathewes ◽  
John A. Westgate
Keyword(s):  
British Columbia ◽  
Sedimentary Rocks ◽  
Lacustrine Sediments ◽  
Igneous Rocks ◽  
The South ◽  
Radiocarbon Dates ◽  
Carbon Contamination ◽  
Horseshoe Lake ◽  
Tephra Beds

Ash-grade Bridge River tephra, identified as such on the basis of shard habit, modal mineralogy, and composition of ilmenite, occurs in sedimentary cores from three lakes located to the south of the previously documented plume and necessitates a significant enlargement of the fallout area of that tephra in southwestern British Columbia.These new, more southerly occurrences are probably equivalent to the ~2350 year old Bridge River tephra, although it can be argued from the evidence at hand that the 14C dates and biotite-rich nature support relationship to a slightly earlier Bridge River event.Large differences exist in the 14C age of sediments immediately adjacent to the Bridge River tephra at these three lake sites; maximum ages of 3950 ± 170 years BP (GX-5549) and 3750 ± 210 years BP (I-10041) were obtained at Phair and Fishblue lakes, respectively, whereas the corresponding age at Horseshoe Lake is only 2685 ± 180 years BP (GX-5757). The two older dates are considered to be significantly affected by old carbon contamination for the bedrock locally consists of calcareous sedimentary rocks and the lacustrine sediments are very calcareous. The 14C date from Horseshoe Lake, which occurs in an area of igneous rocks, appears to be only slightly too old relative to the ~2350 year old Bridge River tephra.Well-dated tephra beds, therefore, can be very useful in assessing the magnitude of old carbon errors associated with radiocarbon dates based on limnic sediments. Calcareous gyttja deposits beneath Bridge River tephra within the study area exhibit old carbon errors of the order of 1350–1550 years.

Radiocarbon chronology of terminal Pleistocene to middle Holocene human occupation in the Middle Cauca Valley, Colombia

2015 ◽  
Vol 363 ◽  
pp. 43-54 ◽  
Author(s):  
Ruth Dickau ◽  
Francisco Javier Aceituno ◽  
Nicolás Loaiza ◽  
Carlos López ◽  
Martha Cano ◽  
...  
Keyword(s):  
Human Occupation ◽  
Middle Holocene ◽  
Terminal Pleistocene ◽  
Radiocarbon Chronology

Present and postglacial rates of uplift for glaciated northern and eastern North America derived from postglacial uplift curves

1970 ◽  
Vol 7 (2) ◽  
pp. 703-715 ◽  
Author(s):  
J. T. Andrews
Keyword(s):  
North America ◽  
Eastern North America ◽  
Hudson Bay ◽  
High Cell ◽  
Uplift Rate ◽  
Radiocarbon Dates ◽  
Marine Deposits ◽  
Maximum Value ◽  
Current Maximum ◽  
A Current

Average rates of postglacial uplift reach a maximum value of nearly 4 m 100 y−1 over southeastern Hudson Bay, and another high cell, with rates of about 2.5 m 100 y−1, lies between Bathurst Inlet and Southampton Island. Current rates of uplift are underestimated if exponential curves are fitted solely to dated raised marine deposits without considering the amount of future recovery. Rates of rebound are, instead, derived from A/t where A is uplift in the first 1000 y since deglaciation, and t is time since deglaciation. For the northwest margin of the former ice sheet coefficients of determination for rate of uplift, at specific times, as a function of distance are [Formula: see text]. Maps of rates of uplift for northern and eastern North America are presented for 8000 y B.P., 6000 y B.P. and the present day. They reveal the existence of three uplift centers and show that rates of uplift declined from a maximum of 10 to 12 m 100 y−1, immediately following deglaciation, to a current maximum of about 1.3 m 100 y−1. Agreement is satisfactory when calculated rates of uplift are compared with those derived from geological observations, radiocarbon dates, and from water-level records. A final map shows isochrones on the uplift rate of ~1 m 100 y−1. The rate dropped to this value about 10 000 y ago on the outer northwest and southeast coasts, whereas the value might not be reached for another 2000 y in southeastern Hudson Bay.

scholarly journals Radiocarbon Chronology of Late Neolithic Settlements in the Tisza-Maros Region, Hungary

Radiocarbon ◽  
1992 ◽  
Vol 34 (3) ◽  
pp. 859-866 ◽  
Author(s):  
Ede Hertelendi ◽  
Ferenc Horváth
Keyword(s):  
Late Neolithic ◽  
Unique Type ◽  
Radiocarbon Dates ◽  
Radiocarbon Data ◽  
Stratigraphic Position ◽  
European Neolithic ◽  
Radiocarbon Chronology ◽  
Developmental Phases

We investigated chronological questions of five Late Neolithic settlements in the Hungarian Tisza-Maros region. Fifty new radiocarbon dates provide an internal chronology for the developmental phases of the tell settlements, and place them into the wider framework of the southeastern European Neolithic. An example is presented of how a unique type of stratigraphic excavation helps the interpretation of radiocarbon data, which are in contradiction with the stratigraphic position of the samples.

An ichthyosaur forefin from the Triassic of British Columbia exemplifying Jurassic features

1991 ◽  
Vol 28 (10) ◽  
pp. 1553-1560 ◽  
Author(s):  
C. McGowan
Keyword(s):  
British Columbia ◽  
North America ◽  
Lower Jurassic ◽  
Upper Triassic ◽  
New Material ◽  
Important Site

New ichthyosaur material is reported from an Upper Triassic locality on Williston Lake, northeastern British Columbia. The paucity of ichthyosaurs from the Triassic of North America make this a potentially important site. An isolated forefin is described, which is unlike that of any Triassic species from North America but which compares closely with certain Lower Jurassic species from England and Germany. The new material suggests that the transition in the ichthyosaurian fauna at the close of the Triassic may have been less abrupt than was previously supposed.

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