Improved Radiocarbon Age Estimation Using the Bootstrap

This paper proposes the use of the statistical bootstrap technique as an aid in combining radiocarbon date estimates The rationale for the use of the bootstrap is the theoretical result that, even if individual date estimates are normally distributed, their combination by the usual formula results in a random quantity that is not normal but rather a mixture of distributions. The bootstrap is a non-parametric, computer-intensive technique. This technique can better estimate the actual distribution of the combined age, leading to more precise confidence intervals. While the bootstrap cannot solve the multiple-intercepts problem in calibration, it can nonetheless lead to better estimates. The benefits of using the bootstrap are especially noticeable when sample sizes are small (as is the case in other applications of this technique).

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Radiocarbon age of rock-boring Hiatella arctica (Linné) and postglacial sea-level change at Cow Head, Newfoundland

Canadian Journal of Earth Sciences ◽

10.1139/e85-012 ◽

1985 ◽

Vol 22 (1) ◽

pp. 136-140 ◽

Cited By ~ 14

Author(s):

Ian A. Brookes ◽

Robert K. Stevens

Keyword(s):

Sea Level ◽

Marine Invertebrate ◽

Sea Level Change ◽

Radiocarbon Date ◽

Radiocarbon Age ◽

Level Change ◽

Hiatella Arctica

Carbonate bedrock surfaces recently exposed at Cow Head, Newfoundland (50°14′N, 57°35′W) are densely riddled with boreholes of Hiatella arctica (Linné), many of which are occupied by subfossil specimens of this bivalve as well as with vermiform burrows of a sponge (? Cliona sp.). A radiocarbon date of 8250 ± 320 years BP (GSC-3433) on several Hiatella valves from the burrows gives the age of a sea-level stand at 8 m asl at the locality, during which penecontemporaneous surf erosion or beach gravel deposition led to the demise of the shells. Other unoccupied cavities in longer exposed bedrock outcrops on Cow Head are contrasted in form and distribution with those of Hiatella and are argued to be boreholes of another marine invertebrate, not positively identified.

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Is it Possible to Find a Good Point Estimate of a Calibrated Radiocarbon Date?

Radiocarbon ◽

10.1017/s0033822200042326 ◽

2007 ◽

Vol 49 (2) ◽

pp. 393-401 ◽

Cited By ~ 32

Author(s):

Adam Michczyński

Keyword(s):

Computer Simulation ◽

Confidence Intervals ◽

Single Point ◽

Radiocarbon Date ◽

Point Estimate ◽

Local Mode ◽

True Value ◽

Point Estimates ◽

Good Point ◽

Accepted Practice

The result from probabilistic calibration of a radiocarbon date is given in the form of a probability density function. Consequently, reporting a 68% or 95% confidence interval has became a commonly accepted practice. However, many users of 14C dates still try to present the results of calibration as a single point. This manner of presentation is often applied during the construction of age-depth models due to its convenience and simplicity. In this paper, the author tests whether it is possible to find a good point estimate of a calibrated 14C date. The idea of the tests is to compare, using computer simulation, the true value of the calendar age with the age calculated based on the probabilistic calibration of the 14C date and the method of finding the point estimate. The test is carried out for the following point estimates: mode, median, average, the central point of the confidence intervals, and the local mode inside the confidence intervals. The results show that none of these may be considered as a good estimate.

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Luminescence Dating as Comparative Data to Radiocarbon Age Estimation of Morasko Spherical Depressions

Radiometric Dating ◽

10.5772/36635 ◽

2012 ◽

Author(s):

Wojciech T.J. ◽

Andrzej Bluszcz

Keyword(s):

Age Estimation ◽

Comparative Data ◽

Luminescence Dating ◽

Radiocarbon Age

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Radiocarbon age of Robinson's Head moraine, west Newfoundland, and its significance for postglacial sea level changes

Canadian Journal of Earth Sciences ◽

10.1139/e77-179 ◽

1977 ◽

Vol 14 (9) ◽

pp. 2121-2126 ◽

Cited By ~ 19

Author(s):

Ian A. Brookes

Keyword(s):

Sea Level ◽

Late Glacial ◽

Radiocarbon Date ◽

Level Curve ◽

Sea Level Changes ◽

Radiocarbon Dates ◽

Radiocarbon Age ◽

Isostatic Uplift ◽

First Approximation

A radiocarbon date of 12 600 ± 140 years BP (GSC-2295) is reported on marine shells from sands within the Robinson's Head kame moraine at Stephen ville, Newfoundland. The moraine was deposited simultaneously with a delta-kame distal to it during a brief interval of increased ice marginal activity. This is marked at Stephenville by a temporary halt in landward marginal recession, but in some other localities around St. George's Bay by a lobate readvance into the late-glacial sea. The date refers to the time of moraine and delta-kame construction and confirms an earlier estimation. Other radiocarbon dates from the area, relating more or less closely to past sea level positions at Robinson's, south of Stephenville, are used, with an hypothetical isostatic uplift curve and a published eustatic sea level curve, to produce a first approximation to postglacial changes of local sea level in the St. George's Bay region.

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Victoria Lower Glacier and Ross Sea Glaciation, Dry Valleys Area, South Victoria Land, Antarctica

Journal of Glaciology ◽

10.1017/s0022143000008868 ◽

1987 ◽

Vol 33 (115) ◽

pp. 293-299 ◽

Cited By ~ 10

Author(s):

T.J.H. Chinn

Keyword(s):

Shear Zone ◽

Ross Sea ◽

Complex Structure ◽

Radiocarbon Date ◽

Dry Valleys ◽

Radiocarbon Age ◽

The North ◽

Victoria Land ◽

Radio Echo Sounding ◽

Echo Sounding

AbstractVictoria Lower Glacier is a complex structure of ice from two distinct sources (Schultz Glacier to the north and a localnévéof Victoria Lower Glacier) that join at a broad median shear zone. Evidence from the margins suggest that both are currently retreating. Algae in a block of frozen stratified sediment from within the ice of the terminal margin has a radiocarbon age of 20 200 ± 2400 year BP (NZ 6531 A), indicating that the glacier has advanced since that time. Superposition of ice levels of Ross Sea I glaciation on a radio echo–sounding profile of bedrock beneath the glacier indicates that it is unlikely that Ross Sea I ice entered the valley. The radiocarbon date supports this finding.

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Victoria Lower Glacier and Ross Sea Glaciation, Dry Valleys Area, South Victoria Land, Antarctica

Journal of Glaciology ◽

10.3189/s0022143000008868 ◽

1987 ◽

Vol 33 (115) ◽

pp. 293-299

Author(s):

T.J.H. Chinn

Keyword(s):

Shear Zone ◽

Ross Sea ◽

Complex Structure ◽

Radiocarbon Date ◽

Dry Valleys ◽

Radiocarbon Age ◽

The North ◽

Victoria Land ◽

Radio Echo Sounding ◽

Echo Sounding

AbstractVictoria Lower Glacier is a complex structure of ice from two distinct sources (Schultz Glacier to the north and a local névé of Victoria Lower Glacier) that join at a broad median shear zone. Evidence from the margins suggest that both are currently retreating. Algae in a block of frozen stratified sediment from within the ice of the terminal margin has a radiocarbon age of 20 200 ± 2400 year BP (NZ 6531 A), indicating that the glacier has advanced since that time. Superposition of ice levels of Ross Sea I glaciation on a radio echo–sounding profile of bedrock beneath the glacier indicates that it is unlikely that Ross Sea I ice entered the valley. The radiocarbon date supports this finding.

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