A 14C age calibration curve for the last 60 ka: the Greenland-Hulu U/Th timescale and its impact on understanding the Middle to Upper Paleolithic transition in Western Eurasia.
ABSTRACT This paper combines the data sets available today for 14C-age calibration of the last 60 ka. By stepwise synchronization of paleoclimate signatures, each of these sets of 14C-ages is compared with the U/Th-dated Chinese Hulu Cave speleothem records, which shows global paleoclimate change in high temporal resolution. By this synchronization we have established an absolute-dated Greenland-Hulu chronological framework, against which global paleoclimate data can be referenced, extending the 14C-age calibration curve back to the limits of the radiocarbon method. Based on this new, U/Th-based Greenland(Hulu) chronology, we confirm that the radiocarbon timescale underestimates calendar ages by several thousand years during most of Oxygen Isotope Stage 3. Major atmospheric 14C variations are observed for the period of the Middle to Upper Paleolithic transition, which has significant implications for dating the demise of the last Neandertals. The early part of "the transition" (with 14C ages > 35.0 ka 14C BP) coincides with the Laschamp geomagnetic excursion. This period is characterized by highly-elevated atmospheric 14C levels. The following period ca. 35.0-32.5 ka 14C BP shows a series of distinct large-scale 14C age inversions and extended plateaus. In consequence, individual archaeological 14C dates older than 35.0 ka 14C BP can be age-calibrated with relatively high precision, while individual dates in the interval 35.0-32.5 ka 14C BP are subject to large systematic age-'distortions,' and chronologies based on large data sets will show apparent age-overlaps of up to ca. 5,000 cal years. Nevertheless, the observed variations in past 14C levels are not as extreme as previously proposed ("Middle to Upper Paleolithic dating anomaly"), and the new chronological framework leaves ample room for application of radiocarbon dating in the age-range 45.0-25.0 ka 14C BP at high temporal resolution.
- SourceAvailable from: Mariana Nabais[Show abstract] [Hide abstract]
ABSTRACT: In the period between ~42500 and ~50000 calendar years ago, represented in the Gruta da Oliveira archeostratigraphy by layers 9-14, Middle Paleolithic humans took shelter in an area of the site located behind a >20 ton boulder fallen at the entrance. Hyena coprolites were also recovered in this area, especially in layers 10-13, where specific spots were recurrently used as latrines, and small fragments of degraded coprolites and digested bone are ubiquitous in micro-morphological thin sections. The pollen in the coprolites suggests that hyenas used the site at times when a temperate forest developed outside, while the charcoal, dominated by Scots pine, gives a cold climate signal. Combined, these data suggest a pattern of alternating use of the cave, with interstadial hyena scavenging of bones accumulated by humans during preceding sta-dials. However, the near-absence of skeletal remains and the lack of juveniles indicate that the site never functioned as a hyena den.First Meeting on Hyaena Dens in archaeological sites of the Iberian Peninsula.; 01/2010
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ABSTRACT: This paper presents a new fossil pollen record from Tso Moriri (32°54′N, 78°19′E, 4512 m a.s.l.) and seeks to reconstruct changes in mean annual precipitation (MAP) during the last 12,000 years. This high-alpine lake occupies an area of 140 km2 in a glacial-tectonic valley in the northwestern Himalaya. The region has a cold climate, with a MAP <300 mm, and open vegetation. The hydrology is controlled by the Indian Summer Monsoon (ISM), but winter westerly-associated precipitation also affects the regional water balance. Results indicate that precipitation levels varied significantly during the Holocene. After a rapid increase in MAP, a phase of maximum humidity was reached between ca. 11 and 9.6 cal ka BP, followed by a gradual decline in MAP. This trend parallels the reduction in the Northern Hemisphere summer insolation. Comparison of different palaeoclimate proxy records reveal evidence for a stronger Holocene decrease in precipitation in the northern versus the southern parts of the ISM domain. The long-term trend of ISM weakening is overlaid with several short periods of greater dryness, which are broadly synchronous with the North Atlantic cold spells, suggesting reduced amounts of westerly-associated winter precipitation. Compared to the mid and late Holocene, it appears that westerlies had a greater influence on the western parts of the ISM domain during the early Holocene. During this period, the westerly-associated summer precipitation belt was positioned at Mediterranean latitudes and amplified the ISM-derived precipitation. The Tso Moriri pollen record and moisture reconstructions also suggest that changes in climatic conditions affected the ancient Harappan Civilisation, which flourished in the greater Indus Valley from approximately 5.2 to 3 cal ka BP. The prolonged Holocene trend towards aridity, punctuated by an interval of increased dryness (between ca. 4.5 and 4.3 cal ka BP), may have pushed the Mature Harappan urban settlements (between ca. 4.5 and 3.9 cal ka BP) to develop more efficient agricultural practices to deal with the increasingly acute water shortages. The amplified aridity associated with North Atlantic cooling between ca. 4 and 3.6 and around 3.2 cal ka BP further hindered local agriculture, possibly causing the deurbanisation that occurred from ca. 3.9 cal ka BP and eventual collapse of the Harappan Civilisation between ca. 3.5 and 3 cal ka BP.Quaternary International 10/2014; 348:93–112. · 2.13 Impact Factor
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ABSTRACT: Extreme precipitation events have a disproportionate impact on landscape evolution and on human constructions, and the frequency and intensity of extreme events may vary with changes in mean climate in the past and in the future. We document the potential for cave sediment archives to record past changes in the frequency of flooding events by characterizing the modern processes responsible for sediment deposition and mobilization during floods and linking these to their incorporation in speleothem deposits. We focus on the Cueva Fria cave system in NW Spain, which like other caves in the region features abundant sandy sediments sourced from dominant sandstone lithologies in the catchment area, in this case delineated by our dye trace study. In this system, the extreme flood conditions in June 2010 caused overflow of the cave stream and deposition of nearly 1 m of sand in sectors near the cave stream and resulted in burial of some stalagmites in > 30 cm of sand in more distal sectors. All sectioned stalagmites growing < 1 m above the overflow channels in these three caves feature sand and silt layers deposited during flood events. Although the high detrital content of these recent materials precludes U/Th dating, radiocarbon dating (especially of actively growing stalagmites) may provide suitable chronologies for reconstruction of past flood chronologies. The basal dates of stalagmites formed in the main overflow channels in Cueva Fria and two other caves in the region cluster around 4 ka. We infer that stalagmite growth in channels was favored by a reduced incidence of flooding in the late Holocene, concomitant with regional drying recorded in numerous terrestrial and marine archives.Geomorphology 09/2014; · 2.58 Impact Factor
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A14C age calibration curve for the last 60 ka: the Greenland-Hulu U/Th
timescale and its impact on understanding the Middle to Upper Paleolithic
transition in Western Eurasia
Bernhard Weningera,*, Olaf Jo ¨risb
aUniversita ¨t zu Ko ¨ln, Institut fu ¨r Ur- und Fru ¨hgeschichte, Radiocarbon Laboratory, Weyertal 125, 50923 Ko ¨ln, Germany
bRo ¨misch-Germanisches Zentralmuseum Mainz, Forschungsbereich Altsteinzeit, Schloß Monrepos, 56567 Neuwied, Germany
a r t i c l e i n f o
Received 4 June 2007
Accepted 15 November 2007
Last Glacial paleoclimate change
Hulu Cave speleothem
Synchronization of paleoclimate archives
Changes in past14C levels
Laschamp geomagnetic excursion
‘‘Middle to Upper Paleolithic dating
a b s t r a c t
This paper combines the data sets available today for14C-age calibration of the last 60 ka. By stepwise
synchronization of paleoclimate signatures, each of these sets of
U/Th-dated Chinese Hulu Cave speleothem records, which shows global paleoclimate change in high
temporal resolution. By this synchronization we have established an absolute-dated Greenland-Hulu
chronological framework, against which global paleoclimate data can be referenced, extending the
14C-age calibration curve back to the limits of the radiocarbon method. Based on this new, U/Th-based
GreenlandHuluchronology, we confirm that the radiocarbon timescale underestimates calendar ages by
several thousand years during most of Oxygen Isotope Stage 3. Major atmospheric14C variations are
observed for the period of the Middle to Upper Paleolithic transition, which has significant implications
for dating the demise of the last Neandertals. The early part of ‘‘the transition’’ (with14C ages>35.0 ka
14C BP) coincides with the Laschamp geomagnetic excursion. This period is characterized by highly-
elevated atmospheric14C levels. The following period ca. 35.0–32.5 ka14C BP shows a series of distinct
large-scale14C age inversions and extended plateaus. In consequence, individual archaeological14C dates
older than 35.0 ka14C BP can be age-calibrated with relatively high precision, while individual dates in
the interval 35.0–32.5 ka14C BP are subject to large systematic age-‘distortions,’ and chronologies based
on large data sets will show apparent age-overlaps of up to ca. 5,000 cal years. Nevertheless, the
observed variations in past14C levels are not as extreme as previously proposed (‘‘Middle to Upper
Paleolithic dating anomaly’’), and the new chronological framework leaves ample room for application of
radiocarbon dating in the age-range 45.0–25.0 ka14C BP at high temporal resolution.
14C-ages is compared with the
? 2008 Elsevier Ltd. All rights reserved.
The timing and duration of possible contact between Neander-
tals and Anatomically Modern Humans (AMH) and the under-
standing of cultural change at the Middle to Upper Paleolithic
transition in Western Eurasia are among the most debated issues in
contemporary paleoanthropology and Paleolithic archaeology. The
period under discussion falls broadly within the time range
45.0–25.0 ka14C BP, which is close to the technical limits of the
The nature of any possible contact between the hominins has
been alternatively suggested to have been extremely short,
implying practically instantaneous replacement of Neandertals by
AMH (cf. Currat and Excoffier, 2004), or to span several thousands
of years, which would allow for the gradual diffusion of AMH into
Eurasia and extended coexistence with Neandertals (e.g., Zilha ˜o,
2006). Central to this debate, the results of radiocarbon dating
provide the backbone for all current models on the chronological
depth and nature of this transition.
Due to difficulties in the extraction and purification of suitable
organic carbon from archaeological bone samples with ages this
close to the technical limits of the radiocarbon method, problems
concerning the validity of dated samples remain. Furthermore, the
exact provenance and taphonomy of samples from the hominin and
archaeological records are often difficult to evaluate, which also
affects the value of many14C ages in this time range. In contrast, the
glacial extension of the14C age calibration curve has made signifi-
cant progress during the last ten years, back to the very limits of the
method. Combined with otherdating approaches fortheLast Glacial
Cycle, calibrated glacial14C ages today allow the construction of
accurate age models for the terrestrial and marine climate proxies
on which our reconstructions of the environmental conditions
during the Middle to Upper Paleolithic transition are based.
* Corresponding author.
E-mail addresses: firstname.lastname@example.org (B. Weninger), email@example.com
(O. Jo ¨ris).
Contents lists available at ScienceDirect
Journal of Human Evolution
journal homepage: www.elsevier.com/locate/jhevol
0047-2484/$ – see front matter ? 2008 Elsevier Ltd. All rights reserved.
Journal of Human Evolution 55 (2008) 772–781
Author's personal copy
Radiocarbon dating at the Middle to Upper Paleolithic
Due to its high analytical accuracy and wide applicability,
radiocarbon dating is fundamental for the chronostratigraphic
framework of the Middle to Upper Paleolithic transition in Western
Eurasia. However, in contrast to the multiple advantages of the
method, due to considerable variation in past atmospheric14C/12C
ratios (cf. Reimer, 2004), the conventional (dimensionless) age-
measurements obtained by radiocarbon dating cannot be directly
compared with the (far less comprehensive) body of results
obtained by other dating methods. Radiocarbon ages first require
independent and absolute age calibration.
For the Holocene and almost the entire Late Glacial (Reimer
et al., 2004; cf. Supplementary Online Material [SOM], Table 3a, 4;
SOM, Fig. 5), tree-ring chronologies allow for a precise age cali-
bration (i.e., transfer of radiocarbon dating results from the initially
‘solar’ years. This age transfer is a necessary requirement for all
research based on radiocarbon dating and chronostratigraphy. At
present state, the application of calibrated14C ages is complicated
by our still fragmentary knowledge of past atmospheric14C levels
during most of the Last Glacial Cycle (cf. Bronk Ramsey et al., 2006;
cf. discussion summarized in Balter, 2006).
The need for calibrated14C ages also applies to geophysical
studies as well as to model simulations aimed at understanding the
global carbon cycle (e.g., Hughen, 2006). Important information
and oceanic14C reservoirs can be obtained from comparing the
known calendric age of a sample with its measured14C age. Model
simulations indicate that the majority of measured rapid (decadal
andcentennial scale)atmospheric14C changes werecausedbysolar
and geomagnetic forcing (e.g., Hughen, 2006), and the continuously
(millenial scale) elevated atmospheric14C levels indicated for most
14C-scale) onto the calendar age scale of
Fig. 1. a. U/Th-dated composite stable oxygen isotope record from Hulu Cave stalagmites MSL, MSD, PD, YT, and H82, China (bottom window; after Wang et al., 2001), compared
with Greenland stable oxygen isotope records from deep ice core drillings at sites GISP2 (top window: top; after Grootes et al., 1993; Meese-Sowers age model: Meese et al., 1997),
GRIP (top window: center; after Johnsen et al., 2001; ‘‘ss09sea’’ age model), and NGRIP (top window: bottom; GICC05-chronology: Andersen et al., 2006, 2007; Svensson et al.,
2006). Vertical scales are in & d18O. Oxygen isotope interstadials labelled in red, and stadial phases in blue (cf. Johnsen et al., 1992; Bjo ¨rck et al., 1998; Walker et al.,1999). b. U/Th-
dated composite stable oxygen isotope record from Hulu Cave stalagmites MSL, MSD, PD, YT, and H82, China (bottom window; after Wang et al., 2001), compared with ‘Hulu-U/Th
age tuned’ Greenland stable oxygen isotope records from Fig.1a, resulting in the GreenlandHulutimescale. Tuning is based on visual matching of specific tie-points (dots) within the
oxygen isotope profiles (see SOM, Information 1).
B. Weninger, O. Jo ¨ris / Journal of Human Evolution 55 (2008) 772–781 773
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of the Last Glacial period imply that the distribution of radiocarbon
than it is today (Hughen, 2006; cf. Hughen et al., 2004, 2006).
It may sound curious, but all geophysical studies aimed at
radiocarbon calibration already require knowledge of calibrated
(calendric) ages. This follows from the mathematical formulas used
in D14C-calculation, which need simultaneous input of numeric14C
values and corresponding calendric ages (D14C-definition: Stuiver
and Polach, 1977;14C-halflife discussion: Chiu et al., 2007). Quite
generally, the construction of a14C age calibration curve extending
far back into the Last Glacial can only be established and tested
hand-in-hand with elaborate calendric age modelling of marine,
atmospheric, and terrestrial14C archives.
Within such an integrated global chronological framework
(SOM, Fig. 1), the extension of the14C age calibration curve should
not be understood as an independent endeavor to be forwarded
only by one dedicated group of researchers (van Andel, 2005).
Instead, the advance of glacial14C age calibration is quite generally
related to global Quaternary research, one important component of
which is the elaboration of highly precise and accurate absolute age
models and chronologies based on terrestrial and marine archives
that naturally extend beyond the limits of14C dating.
Around the transition from the Middle to Upper Paleolithic, the
presently available major data sets that could allow for such age
transfer consistently show highly-elevated atmospheric14C levels
is that the magnitude and temporal patterns of past atmospheric14C
variations were altogether more extreme during the glacial period
than in the Holocene, which has major consequences for the
corrections to be applied to the14C-ages. However, according to
some researchers (e.g., van der Plicht, 2000; van der Plicht et al.,
2004; Reimer et al., 2004; Bronk Ramsey et al., 2006), the observed
patterns of glacial
discrepancies’’ in the scatter of measurements, both within indi-
caused by the unresolved differences in calendric age models (e.g.,
ice core age models), and/or the unknown variations in past carbon
reservoirs, were taken for many years as arguments against the
calibration beyond an official limit of ‘‘26 ka cal BP’’ (van der Plicht,
2000; van der Plicht et al., 2004; Reimer, 2004; Reimer et al., 2004;
Bronk Ramseyet al.,2006).Inconsequence,there presentlyexists no
generally recommended data on which to base an internationally-
accepted standard14C age calibration curve (cf. SOM, Table 5).
14C data are partly obscured by ‘‘unresolved
Fig. 1. (Continued)
B. Weninger, O. Jo ¨ris / Journal of Human Evolution 55 (2008) 772–781774
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Furthermore, the extreme variations in past14C levels observed
in one data set (Beck et al., 2001) have been taken to argue for
a ‘‘Middle to Upper Paleolithic dating anomaly,’’ which is supposed
to be responsible for many apparently wrong14C dating results
around the time of ‘‘the transition’’ (Conard and Bolus, 2003). Such
an ‘‘anomaly’’ may, alternatively, be based on the diverse problems
of sample context and taphonomy of samples relevant for radio-
carbon dating at terrestrial sites, which are difficult to evaluate
even when hominin fossil remains or cultural ‘‘fossil markers’’ are
dated directly. In addition, the extreme spread of data frequently
seen at archaeological sites so close to the apparatus background of
the method with ages beyond ca. 30.0 ka14C BP may, to some large
part, be explained in the often severely degraded collagen of dated
bone, resulting in too young measurements compared with char-
coal samples from a similar context (e.g., Jo ¨ris et al., 2003; Kuzmin
et al., 2004; Richter, 2004). Although important progress in sample
pre-treatment has been made during the last years (Bronk Ramsey
et al., 2004), the extreme sensitivity of14C measurements towards
contamination is amplified by prevailing difficulties in chemical
extraction and purification of the requested indigenous organic
carbon (Hedges and van Klinken, 1992; Brock et al., 2007; Hu ¨ls
et al., 2007).
In parallel to such detailed14C-radiometric and radiochemical
research, the different archaeological hypotheses underlying our
actual perception of the relationship between Neandertals and
AMH and the understanding of cultural change at the Middle to
Upper Paleolithic transition in Western Eurasia are based on the
critical discussion of stratigraphic context and taphonomy of any
dated sample judged as relevant for the hominin and archaeolog-
ical records (cf. Jo ¨ris et al., in press; Jo ¨ris and Street, 2008), in
relation to knowledge of past atmospheric14C levels. Only the
combined interpretation of data from both timescales (14C and
calendric) determines the quantity of time that can be recon-
structed for the period of possible contact between Neandertals
and AMH (to be measured in hominin generations involved in the
process), as is of interest here, since any modelling of paleodemes
within population biology requires precise estimation of the
number of hominin generations, measured on the calendric scale of
The limits of radiocarbon age calibration
Due to the availability of tree-ring chronologies for the last ca.
14,000 years, radiocarbon measurements can be precisely age
calibrated for the Holocene and almost the entire Late Glacial
(Reimer et al., 2004; cf. SOM. Tables 3a, 4; SOM, Fig. 5) with
remaining minimum dating errors limited only by the shape of the
tree-ring14C age calibration curve. However, the critical question is
Fig. 2. Age deviations (cal ka; vertical scale: ice core minus ‘Hulu ages’) of Greenland ice core timescales from Fig.1a (GISP2: Meese-Sowers age model; GRIP: ‘‘ss09sea’’ age model;
NGRIP: GICC05-chronology with 1s [dark gray shade] and 2s [light gray shade] counting errors) as compared to the U/Th timescale for the composite stable oxygen isotope record
from Hulu Cave stalagmites MSL, MSD, PD, YT, and H82 (Wang et al., 2001). Control points are given by40Ar/39Ar-dated major volcanic eruptions (Ash Zone II [AZII] and Campanian
Ignimbrite [CI]) and the age of the Laschamp geomagnetic excursion (LS; discussed in Southon, 2004) as identified in different oxygen isotope records. Error bars along the ?0 cal ka
line of the age deviation axis represent 1s errors for measured Hulu U/Th ages at given composite stalagmite positions. Note that deviations of measured Hulu ages (? 1s U/Th
errors) rarely exceed the 1s errors of the (ice varve counted) GICC05 ice core age model. For further explanations compare with Fig. 1.
B. Weninger, O. Jo ¨ris / Journal of Human Evolution 55 (2008) 772–781775
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B. Weninger, O. Jo ¨ris / Journal of Human Evolution 55 (2008) 772–781 776
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how to extend radiocarbon age calibration back the next ca. 50 ka
to the very limits of the method. Data potentially useful for this
purpose can be derived fromavarietyof archives, each of which has
specific advantages, disadvantages, and dependencies (cf. van der
Plicht, 2000; van der Plicht et al., 2004). The quality of any14C age
calibration will generally depend on at least two basic variables
corresponding to the two timescalesd14C and calendar agedfor
which independent measurements are required. However, in most
practical cases, datingerrors will derive froma much larger number
The construction of an (extended) glacial segment of the14C
calibration curve based, for example, on a series of14C measure-
ments from a high-resolution deep-sea record requires accurate
correlation of parameters that document downcore signatures of
paleoclimate change with independently dated proxies (e.g., stable
oxygen isotope variations as recorded in Greenland ice cores). In
the specific case of marine-based
allowance must be made for potential14C age variations in carbon
reservoirs, since these may have occurred in the past due to oceanic
circulation changes. As a further example, long terrestrial
sequences of laminated limnic sediments can be independently
counted on the base of annual varves (cf. van der Plicht, 2000),
providing ideal short-lived samples (e.g., leaves) with direct refer-
ence to the atmospheric carbon reservoir (e.g., Kitagawa and van
der Plicht, 1998a,b, 2000). However, terrestrial varve sequences
invariously show stratigraphic breaks or reworking of samples, that
can be difficult to identify (for discussion of the Japanese Lake
Suigetsu varve sequence see Jo ¨ris and Weninger, 1999a,b, 2000).
Perhaps the most advantageous source of glacial calibration data is
given when the14C-sample under study can be simultaneously
dated by an independent direct dating method (e.g., U/Th), as is the
case for corals (Bard et al., 1990a,b, 1993). With growth positions
near the equator, coral samples have minimal expected14C reser-
voir variations. In addition, corals can be dated to high-precision by
different Uranium-series techniques, which allows testing of
sample integrity (e.g., Chiu et al., 2005, 2007). With these proper-
ties, and because they provide point-dates that avoid error-prop-
agation, corals are the first-choice samples for glacial
calibration. Their only drawback lies in the limited availability of
suitable samples. Taken together, there exists an impressive pool of
data sets with combined strong potential to support glacial14C age
calibration (van der Plicht, 2000; Reimer et al., 2004; cf. SOM.
In the following we review the presently available data suitable
for glacial14C age calibration and attempt to resolve the afore-
mentioned discrepancies. Our goal is to derive absolute age esti-
mates for each of the different records based on reliable
synchronizations of the related climate proxies. Although some
major component of these efforts is dedicated to quantitative error
analysis (SOM, Information 3.2), in the present paper we focus on
a broader description of the available data and synchronization
procedures. The resulting14C age calibration curve, called CalPal-
2007Hulu, is available on-line (www.calpal.de; www.calpal-online.
de) since May 2007 and updates the previous curve (CalPal-2004/
14C age calibrations, further
Extension of the record: glacial radiocarbon age conversion
based on ice core synchronisms
Reliable synchronisms between marine records and high-reso-
lution Greenland ice cores can be established by comparison of
oxygen isotopic signatures (e.g., Bond et al., 1993; Fronval et al.,
1995; Voelker et al., 1998). Such comparisons have allowed the
North Atlantic cores DSDP-609, V23-81, ODP-644, and PS2644 to
the Greenland ice core age models GRIP and GISP2 (Jo ¨ris and
Weninger,1998,1999a,b, 2000; Voelkeret al.,1998, 2000), resulting
in a first glacial14C age conversion covering the last 50.0 ka BPGISP2
(Jo ¨ris and Weninger, 1998, 1999a,b, 2000).
Though the Greenland ice cores document essentially identical
relative sequences of stadials (GS) and interstadials (GI; Fig.1a,b; cf.
Johnsen et al., 1992; cf. Bjo ¨rck et al., 1998; Walker et al., 1999), the
underlying age models show discrepancies steadily increasing with
core depth amounting to many thousands of years (cf. Southon,
2004) during Oxygen Isotope Stage (OIS) 3. In contrast to a GRIP-
based correlation, calendar ages based on the GISP2 age model
have shown satisfactory agreement (Jo ¨ris and Weninger, 1998,
1999a,b, 2000) with the paired U/Th-14C-coral data available at that
time (Bard et al., 1990a,b, 1993, 1998). In combination, this data
indicated the existence of major non-linear differences between
14C ages and calendar ages (‘distortions’ of the
during the Middle to Upper Paleolithic transition, recognizable as
an extended period with elevated atmospheric14C levels and long
series of radiocarbon plateaus (Jo ¨ris and Weninger, 1998, 1999a,b,
2000). During recent years, the general trend of this initial GISP2-
based14C age conversion model has been supported and refined by
an additional series of more than 400
planktonic foraminifera from the Cariaco Basin in northern Ven-
ezuela, which date back to ca. 60.0 ka BPGISP2(Hughen et al., 2000,
2004), based on correlation of Cariaco varve grayscale values with
the Greenland GISP2 stable oxygen isotope record (Hughen et al.,
14C measurements on planktonic foraminifera from
14C measurements on
Calibration of the record: U/Th-based glacial radiocarbon age
All such methods, data, and procedures are helpful to chro-
nostratigraphic research and allow the first-order construction of
a (relative-age) glacial14C age calibration scheme. However, all of
these comparisons ultimately require application of absolute ages
and, indeed, already the first GISP2 age-based glacial14C age cali-
bration (Jo ¨ris and Weninger,1998,1999a,b, 2000) was shown to be
supported by U/Th-14C-measurements obtained on corals (Bard
et al., 1993) over the entire age range in common back to 40 ka14C
BP (Jo ¨ris and Weninger, 1998).
A remaining problem was then how to obtain additional inde-
pendent absolute dates for ice core timescales. An important step
forward in this respect was achieved by Shackleton and colleagues
(2004) who were the first to apply the method of U/Th-tuning of
Greenland isotope signatures, in this case, based on the Iberian
Margin marine core MD952042. We apply an index ‘‘SFCP’’ to the
Fig. 3. Composite U/Th-derived glacial14C age calibration database (? 1s error bars) and corresponding splined CalPal-2007Hulucalibration curve (? 1s error envelope) for the
time-window 50.0–20.0 ka cal BP/47.0–17.0 ka14C BP (top window), shown in comparison to the Greenland NGRIP stable oxygen isotope record from Andersen et al. (2006, 2007)
and Svensson et al. (2006) tuned to the Hulu Cave U/Th chronology (bottom window; vertical scales are in & d18O; Wang et al., 2001). The glacial part of the CalPal-2007Hulu
database compiles the paired measurements of230Th/234U/238U and14C on pristine corals (Fairbanks et al., 2005), as well as14C measurements on planktonic foraminifera from the
Cariaco Basin, with calendric ages derived from downcore grayscale correlation (Hughen et al., 2006) to the U/Th-dated Hulu oxygen isotope profile (Wang et al., 2001). Further14C
age calibration data are derived by ‘Hulu-tuning’ of marine cores PS2644 (Voelker et al., 2000) and MD952042 (Bard et al., 2004a,b). Used for comparison only, but not included in
the CalPal-2007Huluspline curve, are the data obtained from the ‘‘Arabian Speleothem’’ (van der Plicht et al., 2004). GI ¼Greenland Interstadial (numbers according to Johnsen et al.,
1992). GS ¼Greenland Stadial (numbers according to Johnsen et al.,1992). H3–H4 ¼Heinrich Events. LGM¼Last Glacial Maximum. The age of the Laschamp geomagnetic excursion
and the position of the Campanian Ignimbrite (CI) volcanic eruption, at the very end of GI 9 and at the onset of the Heinrich 4 (H4) event, are marked. For further explanations see
text. GIs and CI are projected from the calendar scale axis to the14C age scale axis (white bars). Note thatdwhen calibratedd14C dates from GSs cannot be resolved at a sufficient
precision beyond GI 9. This is due to large standard deviations for the underlying14C age calibration data series.
B. Weninger, O. Jo ¨ris / Journal of Human Evolution 55 (2008) 772–781 777
Author's personal copy
corresponding absolute-age Greenland age model according to the
authors’ initials: Shackleton, Fairbanks, Chiu, and Parennin. This
initial SFCP-tuning of Greenland ice cores to the (highly repro-
ducible: Mortlock et al., 2005) U/Th clock actually utilized a limited
set of oxygen isotope synchronisms: since the age-transfer was
based on altogether only 1214C ages obtained on planktonic fora-
minifera from the base of the interstadials in MD952042 (Bard
et al., 2004a,b) that the SFCP group used as convenient anchor
points for their ice core calibration (Shackleton et al., 2004;
Shackleton, 2005). Strictly speaking, the new SFCP age model relied
strongly on a small number of widely separated interpolations.
However, though limited in number, these anchor points were
themselves well-fixed on the timescale by an inherently much
larger number of neighbouring oxygen isotope values, as well as by
a large number of neighboring14C values obtained from compari-
sons with an extended set of (total: n¼134) U/Th dated pristine
corals (Fairbanks et al., 2005). The synthetic SFCP U/Th-based14C
age calibration curves (CalPal-2004SFCP; updated in 2005: CalPal-
2005SFCP; www.calpal.de) and the corresponding U/Th-‘stand-
alone’14C age calibration (based solely on14C-U/Th-coral data:
Fairbanks et al., 2005; cf. ‘Fairbanks0805’: http://radiocarbon.ldeo.
columbia.edu/research/radcarbcal.htm) are available on-line, with
regular updates to allow for the growing number of data. The cor-
responding regular comparisons of results achieved by both
methods show good agreement between the ‘stand-alone’ and the
‘synthetic’14C age calibration (SOM, Information 4).
Although the results are quite satisfactory, a yet higher resolu-
tion in absolute-age tuning of Greenland ice cores is possible, and
had indeed already been implicitly established prior to the pio-
neering SFCP study (Shackleton et al., 2004). That study is by
researchersworkingon the reconstruction of northern hemispheric
teleconnections between the North Atlantic climate system and
paleomonsoon records from the Indian Ocean (Schulz et al., 1998;
Burns et al., 2003, 2004), as well as from southwestern and eastern
China (Wang et al., 2001; Cai et al., 2006). Of specific interest to our
studies, due to the availability of a major set of U/Th ages, are the
Hulu Cave speleothems in eastern China that have been shown to
record oxygen isotope signatures with remarkable resemblance to
the isotopic patterns observed in Greenland ice cores (Fig. 1a).
These patterns indicate strong atmospheric/oceanic coupling
between East Asia and the North Atlantic region (Wang et al., 2001).
Using the Hulu Cave oxygen isotope signature, and based on the
transfer of230Th ages obtained from Hulu Cave (cf. supplementary
information in Wang et al., 2001) to Greenland ice cores, we have
derived a new absolute age calibration for the GRIP and GISP2
records. As shown in Fig. 1b, for the entire OIS 3, the new U/Th-
based GreenlandHuluice core age model finds independent support
in the recent re-counting of ice varves in the NGRIP and GRIP and,
partly, in the GISP2 ice cores (GICC05-chronology: Andersen et al.,
2006, 2007; Svensson et al., 2006). Nevertheless, despite the
overall highly satisfactory agreement between the point-estab-
lished U/Th-based absolute age model and the consecutively-
counted varve-based GICC05 relative age model, the accumulated
ice counting errors still remain large and give reason to prefer the
230Th-ages, due to their smaller quantitative and non-additive
errors (Fig. 2).
Additional control of the new GreenlandHulu timescale is
possible by using independently-dated volcanic marker horizons
that are well-fixed within differentoxygenisotope records. The two
most important of these volcanic markers, both dated indepen-
(39,395?51 BPAr/Ar; De Vivo et al., 2001; cf. Giaccio et al., 2006) and
the North Atlantic Ash Zone II (54.5 ?1.0 ka BPAr/Ar; Southon, 2004).
In both cases the measured absolute ages are in close agreement
to their ages as predicted on the GreenlandHulutimescale (Fig. 2;
SOM, Fig. 1).
40Ar/39Ar-methods, are the Campanian Ignimbrite
Based on the new GreenlandHulu timescale, and utilizing
a recent update of the Cariaco marine14C age calibration, which has
been synchronized with the Hulu Cave speleothems (Hughen et al.,
2006), we have constructed a new glacial14C age calibration curve
for the last 60.0 ka cal BPHulu: CalPal-2007Hulu(Fig. 3; SOM, Figs.
3–5; www.calpal.de; www.calpal-online.de). In comparison to our
previous glacial calibration curve (CalPal-2004/2005SFCP), which
was only partly built on U/Th ages, the new calibration CalPal-
2007Huluis now entirely referenced to U/Th ages. It combines the
recently-compiled U/Th coral database of Fairbanks and colleagues
(cf. Chiu et al., 2005, 2007; Fairbanks et al., 2005) with the new
Hulu-tuned radiocarbon data from Cariaco (Hughen et al., 2006),
and finally also includes the14C data from the high resolution
(GreenlandHulu-tuned) marine cores MD952042 and PS2644.
Given the present state of research for glacial14C age calibration,
we advise to systematically compare and combine the available14C
data sets along with an integrated and chronometrically cross-
checked geochronological framework based on a larger number of
high-resolution paleoclimate proxy data, which are supported by
different dating methods. The new synthetic U/Th based Green-
2007Huluare both sufficiently precise to support absolute dating of
a wide variety of archaeological and geoscientific archives and
climate proxies back to ca. 60 ka calBPHulu(via14C-calibration). This
chronology is in good agreement with earlier attempts for glacial
14C age conversion (Jo ¨ris and Weninger, 1998, 1999a,b, 2000), such
that previously achieved results remain valid. However, the new
framework shows the glacial atmospheric14C levels along with
a wide range of synchronous global climate processes in previously
consistently document highly elevated14C levels over most of OIS 3
and 2, a period during which the radiocarbon timescale underes-
and magnitude of such deviations when comparing
records with other radiometric non-14C-measurements.
Due to the specific paleoclimatic synchronizations underlying
the construction of the GreenlandHulutimescale, it is possible to
directly link changes in past atmospheric
Glacial climate signatures (Fig. 3). With respect to these paleo-
climate synchronisms, future changes in or further refinements of
underlying calendar age models (i.e., GreenlandHulutimescale) will
not significantly alter the now well-established relations between
14C age on the one hand and the basic climatic ‘status’ (i.e., stadial
vs. interstadial context) on the other, although the typically rather
high standard deviations of14C measurements>35.0 ka14C BP do
not allow us to distinguish with high temporal resolution, between
specific paleoclimatic oscillations.
Due to highly-elevated atmospheric14C levels, samples with
ages older than 35.0 ka14C BP calibrate at relatively high precision
(within the limits of given standard deviations). In the following
younger segment, ca. 35.0–32.5 ka14C BP, the calibration curve
shows a series of large-scale
plateaus including several sub-plateaus. The multiple ‘distortions’
of the14C-scale in this age range, as indicated by the present data,
artificiallyextend this interval by uptoca. 5,000 calyears. These are
the worst-case variations. Beyond these variations, our combined
data (CalPal-2007Hulu) do not confirm the existence of extreme
frequencies and amplitudes in atmospheric14C levels as variously
propagated (Beck et al., 2001).
Central questions, to be adressed in future, relate to the potential
effects of temporal and regional variations in marine carbon reser-
voirs (cf. Grootes and Sarnthein, 2006). As applies for the Late
14C/12C ratios to Last
14C age inversions and extended
B. Weninger, O. Jo ¨ris / Journal of Human Evolution 55 (2008) 772–781778
Author's personal copy
Glacial, comparisons of marine and terrestrial records in the Cariaco
Basin (equatorial region) demonstrate that glacial marine reservoir
values can vary, abruptly, within the range of a few hundred14C-
years (cf. Hughen et al., 2004; Kromer et al., 2004; cf. SOM, Table 3a;
SOM, Fig. 5). Although there are indications for even more extreme
marine carbon reservoir variations, as well as large regional differ-
ences (cf. Grootes and Sarnthein, 2006), the presently available14C
measurements on planktonic (near-surface living) foraminifera in
PS2644 and MD952042 do not show apparent deviations and
therefore have no significant effect on the shape of the CalPal-
2007Hulucalibration curve. Future comparisons of existing floating
tree-ring sequences from terrestrial interstadial sediments (Hae-
saerts et al., 2003, 2005, pers. comm.), when correlated to the
marine and ice core paleoclimate archives, with14C levels derived
from marine interstadial archives, will give first approximations of
the amplitude of change of interstadial marine reservoir effects.
The potential effects of the Laschamp paleomagnetic excursion
on atmospheric14C levels also require further attention. To evaluate
these, the precise relative and absolute dating of the Campanian
Ignimbrite (CI) volcanic event, which took place in the Phlegrean
Fields, Italy, some 40,000 years ago (see above; De Vivo et al., 2001),
is of key-importance: Mediterranean oxygen isotope records fix the
CI ash layer stratigraphically immediately before the Heinrich 4
event (Ton-That et al., 2001), and synchronisms with Greenland ice
core chronologies allow the CI event to be linked to an extreme
peak in volcanic sulphur recorded at 40,012 BPGISP2in the GISP2 ice
core at the veryend of GI 9 (Zielinski et al.,1996,1997; Giaccio et al.,
2006). In the Mediterranean, the Y5 ash layer of the CI post-dates
the Laschamp geomagnetic excursion, which is identified by rock
magnetic parameters and10Be flux, allowing for further tightening
of both the CI-eruption and the Laschamp excursion (roughly
dating to between ca. 43.0 and 40.0 ka BPGISP2-Hulu; Fig. 3; cf.
Voelker et al., 2000; Southon, 2004) within the Greenland ice core
chronologies (Giaccio et al., 2006; cf. Muscheler et al., 2005).
Corresponding radiocarbon measurements for the end of the
Laschamp excursion and for the time of CI eruption can be esti-
mated at 34.8–34.7 ka14C BP (Jo ¨ris et al., in press).
In archaeological sequences the CI seperates both Middle
Paleolithic and the earliest Upper Paleolithic (EUP) industries,
which are found below the CI, from the Aurignacian above the
tephra layers, placing the Middle to Upper Paleolithic transition, at
least in parts of Italy and Eastern Europe, at around 40.0 ka cal
BPHuluor slightly before this date (Fedele et al., 2008; Hoffecker
et al., 2008; cf. Jo ¨ris and Street, 2008). At least within these regions
‘‘the transition’’ would thus fall into the Laschamp event. That this
geomagnetic excursion may have resulted in enhanced levels of
high-amplitude ‘distortions’ of radiocarbon ages at PS2644, in
parallel to corresponding variations in magnetic susceptibility
(Voelker et al., 2000). Within the later part of the Laschamp
geomagnetic excursion, at PS2644, offsets between calendar ages
and uncalibrated radiocarbon dates mount up to a total of ca.
6,000–7,000 years, probably even 8,000 years at a calendar age of
around 40.5 ka BPGISP2-Hulu(Fig. 3; cf. Weninger and Jo ¨ris, 2004).
This extreme offset may find confirmation in another series of
radiocarbon dates obtained at high stratigraphic resolution from
core CT85-5 in the Thyrrenian Sea (Giaccio et al., 2006). Once
confirmed, such ‘distortions’ would make it all the more difficult
to understand terrestrial radiocarbon measurements, at least
when obtained from archaeological or paleoanthropological
contexts, for which high-resolution continual stratigraphic control
is lacking. At best, such extreme variations in past atmospheric14C
levels could be identified in data obtained from well-stratified
sample sequences. At worst, such age ‘distortions’ would be
hidden in poorly sampled sequences or those lacking fine strati-
14C has already been indicated by corresponding
Glacial14C age calibration is necessary as background to all
theoretical studies that require calendar age input. This concerns
geophysical modelling just as much as the paleodemographic,
environmental, or cultural modelling necessary to understand the
replacement of Neandertals by AMH at the Middle to Upper
Paleolithic transition in Western Eurasia. This paper demonstrates
that the majority of ‘discrepancies’ observed for the14C data series
aiming at glacial14C age calibration under study by the interna-
tional radiocarbon community (Reimer, 2004) are largelycaused by
the use of incompatible underlying calendar age models. As soon as
these data series are referred to a single age model, the scatter in
data largely disappears (cf. Jo ¨ris and Weninger, 1998, for a first
GISP2-tuned14C age conversion), allowing for14C age conversion
all theway backtothe verylimits of the radiocarbon dating method
(cf. Jo ¨ris and Weninger, 1998, 1999a,b, 2000).
Following critical evaluation of the available calibration records
at high temporal resolution, in context with published U/Th
measurements obtained on speleothems from the Hulu Cave in
eastern China (Wang et al., 2001), we have now developed a new
glacial14C age calibration: CalPal-2007Hulu. This new chronological
framework agrees well with earlier schemes (Jo ¨ris and Weninger,
1998, 1999a,b, 2000; Weninger and Jo ¨ris, 2004) but shows more
detail, both in terms of past atmospheric14C levels, as well as
supplying a set of absolute ages for the underlying paleoclimate
proxies. Following detailed comparisons with the recently estab-
lished GICC05-age model (Andersen et al., 2006, 2007; Svensson
et al., 2006), we conclude that the new GreenlandHuluchronology
has sufficient precision to support
The data incorporated in CalPal-2007Hulu give evidence that
glacial atmospheric14C levels do not show the extreme variations
sometimes propagated (Beck et al., 2001; Conard and Bolus, 2003).
Although we must allow for the possibility of large offsets between
14C ages and calendric ages due to the Laschamp geomagnetic
excursion,14C age calibration is made possible for the period 45.0–
25.0 ka14C BP. Further advances in14C age calibration of terrestrial
archives are foreseeable for the near future due to the huge
potential offered by U/Th-dated speleothem records that provide
high-resolution terrestrial paleoclimate information (Henderson,
2006). This information can be linked to a wide variety of radio-
carbon-dated marine and terrestrial archives. Due to the wide-
spread distribution of speleothems, they can be used both to
synchronize as well as age calibrate a wide variety of climate
proxies all over the globe.
To conclude, we expect chronological refinement on both
timescales to be of increasing relevance for the understanding of
the temporal depth at the Middle to Upper Paleolithic transition
and the time of demise of the last Neandertals.
14C age calibration at high
We greatfully acknowledge the constant encouragement by
Sabine Gaudzinski-Windheuser and Tjeerd van Andel to proceed
with our studies. Our special thanks go to Rick Fairbanks, Konrad
Hughen, and Nick Shackleton (y) for sharing numeric data prior to
publication, and to Paul Haesaerts for some fruitful discussions.
For critical comments and providing us with up-to-date literature,
we are especially thankful to Hans van der Plicht and other
members of the IntCal group who have constantly challenged us to
improve quality control and error analyses of the available14C age
calibration data sets. We would also like to thank anonymous
reviewers as well as Susan Anto ´n for their constructive and helpful
B. Weninger, O. Jo ¨ris / Journal of Human Evolution 55 (2008) 772–781779
Author's personal copy
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