Magnetostratigraphy and cosmogenic dating of Wonderwerk Cave: New constraints for the chronology of the South African Earlier Stone Age

doi:10.1016/j.quascirev.2021.106907

Quaternary Science Reviews

Volume 259, 1 May 2021, 106907

https://doi.org/10.1016/j.quascirev.2021.106907 Get rights and content

Highlights

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New chronology of Wonderwerk cave based on magnetostratigraphy and cosmogenic ages.
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Oldowan industry in Wonderwerk is robustly correlated with the Olduvai subchron.
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Onset of the Acheulean in St. 11 is older than ca. 1.07 Ma.
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Cosmogenic burial ages are affected by temporal changes in the inherited ²⁶Al/¹⁰Be.
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A stabilization of the Kalahari sands during the Middle Pleistocene.

Abstract

Cave sediments pose dating challenges due to complex depositional and post-depositional processes that operate during their transport and accumulation. Here, we confront these challenges and investigate the stratified sedimentary sequence from Wonderwerk Cave, which is a key site for the Earlier Stone Age (ESA) in Southern Africa. The precise ages of the Wonderwerk sediments are crucial for our understanding of the timing of critical events in hominin biological and cultural evolution in the region, and its correlation with the global paleontological and archaeological records. We report new constraints for the Wonderwerk ESA chronology based on magnetostratigraphy, with 178 samples passing our rigorous selection criteria, and fourteen cosmogenic burial ages. We identify a previously unrecognized reversal within the Acheulean sequence attributed to the base of the Jaramillo (1.07 Ma) or Cobb Mtn. subchrons (1.22 Ma). This reversal sets an early age constraint for the onset of the Acheulean, and supports the assignment of the basal stratum to the Olduvai subchron (1.77–1.93 Ma). This temporal framework offers strong evidence for the early establishment of the Oldowan and associated hominins in Southern Africa. Notably, we found that cosmogenic burial ages of sediments older than 1 Ma are underestimated due to changes in the inherited ²⁶Al/¹⁰Be ratio of the quartz particles entering the cave. Back calculation of the inherited ²⁶Al/¹⁰Be ratios using magnetostratigraphic constraints reveals a decrease in the ²⁶Al/¹⁰Be ratio of the Kalahari sands with time. These results imply rapid aeolian transport in the Kalahari during the early Pleistocene which slowed during the Middle Pleistocene and enabled prolonged and deeper burial of sand while transported across the Kalahari Basin.

Introduction

Southern Africa has a rich fossil and archaeological record. The precise ages of archaeological bearing deposits in South Africa are crucial for our understanding of the timing of critical events in hominin biological and cultural evolution in the region (Woodborne, 2016), and its correlation with the global paleontological and archaeological record. However, methodological constraints of the currently available chronological data limit our ability to construct a robust chronological framework for human evolution in the region. Previous chronometric studies have employed various dating techniques, including magnetostratigraphy (Herries et al., 2009; Mcfadden et al., 1979; Thackeray et al., 2002), cosmogenic burial dating of sediments and artifacts (Gibbon et al., 2009, 2014; Granger et al., 2015), electron spin resonance dating of tooth enamel (Dirks et al., 2017; Grun et al., 1996; Porat et al., 2010) and U-Th or U-Pb dating of tooth enamel and flowstone (Albarede et al., 2006; Dirks et al., 2017; Pickering et al., 2010, 2011). Here, we focus on the Earlier Stone Age (ESA) section in Excavation 1 at Wonderwerk Cave and integrate magnetostratigraphy and cosmogenic burial dating in an attempt to better constrain the South African ESA chronology.

Wonderwerk Cave, a 140 m long phreatic tube located in the eastern flanks of the Kuruman Hills, between the towns of Danielskuil and Kuruman (Fig. 1A), is a site with unique potential for developing a chronometric baseline for archaeological industries in the region. Although Wonderwerk Cave lacks hominin fossils, its Pleistocene deposits include both faunal and botanical remains as well as archaeological material in a stratified cave fill that spans the Oldowan through a developed Acheulean (Chazan et al., 2008, 2012). The primary context of the Wonderwerk Cave lithic and faunal materials (Goldberg et al., 2015), contrasts with many of the rich Cradle of Humankind paleontological localities (Fig. 1A), which are interpreted as doline infills in which artifacts and fossils are in secondary contexts (Dirks and Berger, 2013; Partridge and Maud, 2000). Since finds at Wonderwerk Cave are in situ, they provide a clear and ordered framework to investigate the association of artifacts and ecofacts with age determinations. Within the Wonderwerk sequence we can identify the earliest intentional occupation of a cave associated with Oldowan tools (Chazan et al., 2012), as well as onset of technological innovations including biface manufacture and the elaboration of biface forming (Chazan, 2015). Adding to the significance of the site is the identification of the use of fire in the early Acheulean strata (Berna et al., 2012). Critically, fixing the age of the Oldowan at Wonderwerk Cave provides a means of resolving debates about the timing of this industry and related hominin species in Southern Africa.

Previous chronometric efforts at Wonderwerk Cave have included radiocarbon for the uppermost levels (Ecker et al., 2017); optically stimulated luminescence (OSL) for horizons younger than ∼0.3 Ma (Chazan et al., 2008, 2020); cosmogenic burial ages for sediments older than ∼0.5 Ma (Chazan et al., 2008, 2012; Matmon et al., 2012), magnetostratigraphy (Chazan et al., 2008, 2012; Matmon et al., 2012); U-Th dating (Beaumont and Vogel, 2006) and U-Pb dating (Pickering, 2015) of buried stalagmites younger or older than ∼0.3 Ma, respectively. Here we present new paleomagnetic data and cosmogenic burial dates and compare the new results with former chronostratigraphic constraints with specific aims to: 1) test the age of the basal archaeological deposits and the associated Oldowan lithic industry, 2) refine the magnetostratigraphy of the Acheulean strata, and 3) explore processes associated with sediment deposition in the cave and the corresponding cosmogenic burial ages.

Section snippets

Geological and archaeological stratigraphy

Samples for this study were collected from two profiles which were excavated between the 1970s and the early 1980s by Peter Beaumont (Fig. 1) (Beaumont and Vogel, 2006; Horwitz and Chazan, 2015). Both sections are located in Excavation 1 (hereafter Exc. 1), which lies ca. 30m in from the cave entrance (Fig. 1B). The North profile, termed hereafter Exc. 1-N, is along the 28/29 grid line (the original grid was established by Beaumont in yards). The South profile (Exc. 1-S) is six yards (5.48m) to

Paleomagnetic stratigraphy

Paleomagnetic sampling of Exc. 1 was carried out during excavation seasons 2005, 2007, 2016 and 2018. The pre-2016 data included 87 samples from Exc. 1-N and Exc. 1-E, the perpendicular abutting profile to the east of Exc. 1-N (Fig. 1B). These were used to construct an initial magnetostratigraphic age model (Chazan et al., 2008, 2012; Matmon et al., 2012). During seasons 2016 and 2018 we collected additional 282 samples: 226 samples from Exc. 1-N and 56 samples from Exc. 1-S. Paleomagnetic

Magnetostratigraphy

Fig. 2 shows representative demagnetization results of paleomagnetic samples with nearly ideal behaviors, from which an unambiguous polarity state can be inferred, as well as results failing to provide a robust paleomagnetic direction. An ideal behavior is characterized by a univectorial magnetization pointing northward and upward (declination near zero and negative inclination) or southward and downward (declination near 180 and positive inclination), for normal and reverse polarity,

Updated age model of Exc. 1 sequence

The paleomagnetic – cosmogenic age model of Wonderwerk sequence is based on tying the paleomagnetic polarity sequences in Exc. 1–N and Exc. 1–S to the most recent Quaternary geomagnetic polarity timescale (Channell et al., 2020) and to the cosmogenic burial ages (Fig. 3).

The archaeological evidence in St. 7-6 of a shift towards highly refined handaxes (Chazan, 2015) suggests that the upper units are younger than the Brunhes-Matuyama (B-M) boundary (0.77 Ma). Thus, we assign St. 7-6 in Exc. 1-S

Summary and conclusions

This article reports the results of paleomagnetic and cosmogenic burial dating at Excavation 1, Wonderwerk Cave, South Africa, updating previously reported results (Matmon et al., 2012) with analysis of additional seven cosmogenic ages and 282 paleomagnetic samples. From a total of 323 paleomagnetic samples in Exc. 1-N and Exc. 1-S, 178 samples pass our selection criteria with MAD <15, DANG <30 and angular deviation from GAD field <45°. These data enabled the construction of a revised age model

Author contributions

M.C and L.K.H initiated and designed the project, directed the archaeological campaigns and led field work; R.S carried out the paleomagnetic analyses, made the figures and led the manuscript writing; A.M carried out the cosmogenic isotopes analyses; Y.E. assisted with the paleomagnetic analyses; All authors contributed equally to final data analyses and to manuscript writing.

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgments

Research at Wonderwerk Cave is carried out under permit from the South African Heritage Resources Agency. We are grateful for support from David Morris, head of the Department of Archaeology, McGregor Museum. Funding for this research is provided by grants from the Canadian Social Sciences and Humanities Research Council and the Paleontological Scientific Trust. We thank two anonymous reviewers for their insightful comments on this manuscript and Darryl Granger for reviewing two versions of

References (64)

D.C. Argento et al.
Modeling the earth's cosmic radiation
Nucl. Instrum. Methods Phys. Res. Sect. B Beam Interact. Mater. Atoms
(2013)
G. Balco et al.
A complete and easily accessible means of calculating surface exposure ages or erosion rates from Be-10 and Al-26 measurements
Quat. Geochronol.
(2008)
J.E.T. Channell et al.
Timing of Quaternary geomagnetic reversals and excursions in volcanic and sedimentary archives
Quat. Sci. Rev.
(2020)
M. Chazan et al.
The Oldowan horizon in Wonderwerk Cave (South Africa): archaeological, geological, paleontological and paleoclimatic evidence
J. Hum. Evol.
(2012)
M. Chazan et al.
Radiometric dating of the earlier Stone Age sequence in excavation I at Wonderwerk Cave, South Africa: preliminary results
J. Hum. Evol.
(2008)
J. Chmeleff et al.
Determination of the Be-10 half-life by multicollector ICP-MS and liquid scintillation counting
Nucl. Instrum. Methods B
(2010)
P.H.G.M. Dirks et al.
Hominin-bearing caves and landscape dynamics in the Cradle of Humankind, South Africa
J. Afr. Earth Sci.
(2013)
R.J. Gibbon et al.
Early Acheulean technology in the Rietputs Formation, South Africa, dated with cosmogenic nuclides
J. Hum. Evol.
(2009)
R.J. Gibbon et al.
Cosmogenic nuclide burial dating of hominin-bearing Pleistocene cave deposits at Swartkrans, South Africa
Quat. Geochronol.
(2014)
D.E. Granger et al.
Dating sediment burial with in situ-produced cosmogenic nuclides: theory, techniques, and limitations
Earth Planet Sci. Lett.
(2001)

A.I.R. Herries et al.

A multi-disciplinary seriation of early Homo and Paranthropus bearing palaeocaves in southern Africa

Quat. Int.

(2009)

A.I.R. Herries et al.

Palaeomagnetic analysis of the Sterkfontein palaeocave deposits: implications for the age of the hominin fossils and stone tool industries

J. Hum. Evol.

(2011)

A.J. Hidy et al.

Glacial-interglacial variation in denudation rates from interior Texas, USA, established with cosmogenic nuclides

Earth Planet Sci. Lett.

(2014)

C.P. Kohl et al.

Chemical isolation of quartz for measurement of Insitu-produced cosmogenic nuclides

Geochem. Cosmochim. Acta

(1992)

G. Korschinek et al.

A new value for the half-life of Be-10 by Heavy-Ion Elastic Recoil Detection and liquid scintillation counting

Nucl. Instrum. Methods B

(2010)

K. Kuman et al.

The Rietputs 15 site and early Acheulean in South Africa

Quat. Int.

(2018)

K. Kuman et al.

The Oldowan industry from Swartkrans Cave, South Africa, and its relevance for the African Oldowan

J. Hum. Evol.

(2018)

N. Lifton et al.

Scaling in situ cosmogenic nuclide production rates using analytical approximations to atmospheric cosmic-ray fluxes

Earth Planet Sci. Lett.

(2014)

A. Matmon et al.

Unraveling rift margin evolution and escarpment development ages along the Dead Sea fault using cosmogenic burial ages

Quat. Res.

(2014)

A. Matmon et al.

New chronology for the southern Kalahari Group sediments with implications for sediment-cycle dynamics and early hominin occupation

Quat. Res.

(2015)

P.L. Mcfadden et al.

Paleomagnetism and the age of the Makapansgat hominid site

Earth Planet Sci. Lett.

(1979)

K. Nishiizumi

Preparation of Al-26 AMS standards

Nucl. Instrum. Methods B

(2004)

K. Nishiizumi et al.

Absolute calibration of Be-10 AMS standards

Nucl. Instrum. Methods B

(2007)

R. Pickering et al.

Contemporary flowstone development links early hominin bearing cave deposits in South Africa

Earth Planet Sci. Lett.

(2011)

R. Pickering et al.

U-Pb dating of calcite-aragonite layers in speleothems from hominin sites in South Africa by MC-ICP-MS

Quat. Geochronol.

(2010)

N. Porat et al.

New radiometric ages for the Fauresmith industry from Kathu Pan, southern Africa: implications for the Earlier to Middle Stone Age transition

J. Archaeol. Sci.

(2010)

H. Ruther et al.

Laser scanning for conservation and research of African cultural heritage sites: the case study of Wonderwerk Cave, South Africa

J. Archaeol. Sci.

(2009)

S. Vainer et al.

Coupling cosmogenic nuclides and luminescence dating into a unified accumulation model of aeolian landforms age and dynamics: the case study of the Kalahari Erg

Quat. Geochronol.

(2018)

S. Vainer et al.

Provenance and depositional environments of Quaternary sediments in the southern Kalahari Basin

Chem. Geol.

(2018)

F. Albarede et al.

U-Pb dating of enamel from the Swartkrans Cave hominid site (South Africa) by MC-ICP-MS

Geochem. Cosmochim. Acta

(2006)

P.B. Beaumont et al.

On a timescale for the past million years of human history in central South Africa

South Afr. J. Sci.

(2006)

F. Berna et al.

Microstratigraphic evidence of in situ fire in the Acheulean strata of Wonderwerk cave, northern Cape province, South Africa

Proc. Natl. Acad. Sci. U.S.A.

(2012)

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Magnetostratigraphy and cosmogenic dating of Wonderwerk Cave: New constraints for the chronology of the South African Earlier Stone Age

Highlights

Abstract

Introduction

Section snippets

Geological and archaeological stratigraphy

Paleomagnetic stratigraphy

Magnetostratigraphy

Updated age model of Exc. 1 sequence

Summary and conclusions

Author contributions

Declaration of competing interest

Acknowledgments

Nucl. Instrum. Methods Phys. Res. Sect. B Beam Interact. Mater. Atoms

Quat. Geochronol.

Quat. Sci. Rev.

J. Hum. Evol.

J. Hum. Evol.

Nucl. Instrum. Methods B

J. Afr. Earth Sci.

J. Hum. Evol.

Quat. Geochronol.

Earth Planet Sci. Lett.

Quat. Int.

J. Hum. Evol.

Earth Planet Sci. Lett.

Geochem. Cosmochim. Acta

Nucl. Instrum. Methods B

Quat. Int.

J. Hum. Evol.

Earth Planet Sci. Lett.

Quat. Res.

Quat. Res.

Earth Planet Sci. Lett.

Nucl. Instrum. Methods B

Nucl. Instrum. Methods B

Earth Planet Sci. Lett.

Quat. Geochronol.

J. Archaeol. Sci.

J. Archaeol. Sci.

Quat. Geochronol.

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U-Pb dating of enamel from the Swartkrans Cave hominid site (South Africa) by MC-ICP-MS

Geochem. Cosmochim. Acta

On a timescale for the past million years of human history in central South Africa

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Microstratigraphic evidence of in situ fire in the Acheulean strata of Wonderwerk cave, northern Cape province, South Africa

Proc. Natl. Acad. Sci. U.S.A.