Holocene LSA archaeology from Equus Cave, Buxton-Norlim Limeworks, South Africa : an analysis of the bone tool assemblage

Abstract: Equus Cave, Buxton-Norlim Limeworks, near Taung, North West Province, South Africa, was first excavated between 1978 and 1982. While the site dates to the terminal Pleistocene and Holocene the precise age of the different layers is debated, as is the technological assignment of the deepest deposits, which are said to contain both Later or Middle Stone Age elements. While the faunal assemblage and some of the human remains have been published, the archaeology has never been fully analysed or reported. New excavations in 2012 revealed numerous artefacts including ochre, something not previously noted for this site. Comparison of total lithic artefact counts versus faunal NISPs and MNIs shows that the height of human occupation occurred during the Holocene, with preliminary analysis of the >6000 lithic assemblage indicating a dominance of notched artefacts, which, coupled with the presence of 16 bone points, is characteristic of other HoloceneWilton (Later Stone Age) sites in the region. The focus of this paper is the 16 bone points, which include projectile points and link-shafts, and how these items were manufactured and used. The results provide one of the first detailed descriptions of Later Stone Age bone tools, including rare specimens that are mostly complete or still preserve the tips, making an important contribution to our limited understanding of Later Stone Age bone tool technology

Dredging and canal gate technologies in Portus, the ancient harbour of Rome, reconstructed from event stratigraphy and multi-proxy sediment analysis

Ancient harbours are rich archives of human-environment interaction. However, dating harbour deposits and correlating their stratigraphy is a major challenge because of typically high sedimentation rates over short periods and possible curative dredging events. Portus, the maritime harbour of Rome at the height of the Roman Empire, was a port complex composed of basins and canals connecting the commercial harbour to Rome via the Tiber River. Sediment core CPS1 in the narrowest of these canals, Canale Traverso, is located centrally in what was the capital city's commercial hub and contains a continuous harbour depositional record with average sedimentation rates greater than 1 cm per year. Here we use piston coring, high-resolution core scanning and a multi-proxy sediment analysis including for the first time paleo- and rock-magnetism, and bulk and clay mineralogy in order to overcome the problems of dating harbour deposits and correlating their stratigraphy. The method allowed precise identification of major reworked events, including a dredged deposit and a hyperpycnal deposit, which improve the chronostratigraphy and water depth reconstruction, and sheds light on harbour technologies at the height of the Roman Empire. A debris layer with abundant ceramic fragments and rocks marks the decommissioning of Canale Traverso and provides a new chronostratigraphic marker at Portus. Multi-proxy riverine input signatures point to the possible use of canal gate technology for water flow management

Orbital precession modulates interannual rainfall variability, as recorded in an Early Pleistocene speleothem

Interannual variability of African rainfall impacts local and global communities, but its past behavior and response in future climate projections are poorly understood. This is primarily due to short instrumental records and a lack of long high-resolution palaeoclimate proxy records. Here we present an annually resolved 91,000 year Early Pleistocene record of hydroclimate from the early homininbearing Makapansgat Valley, South Africa. Changes in speleothem annual band thickness are dominated by precession over four consecutive orbital cycles with strong millennial-scale periodicity. The frequency of interannual variability (2.0–6.5 yr oscillations) does not change systematically, yet its amplitude is modulated by the orbital forcing. These long-term characteristics of interannual variability are reproduced with transient climate model simulations of water balance for South Africa from the Late Pleistocene to Recent. Based on these results, we suggest that the frequency of interannual variations in southern African rainfall is likely to be stable under anthropogenic warming, but that the size of year-to-year variations may increase. We see an orbitally forced increase in the amplitude of interannual climate variability between 1.8 Ma and 1.7 Ma coincident with the first evidence for the Acheulean stone tool technology

Archaeomagnetic evidence for climate change at Sibudu Cave

In situ magnetic susceptibility (MS) measurements were undertaken on the north, south and east section walls of the trial trench in Sibudu Cave, KwaZulu-Natal, South Africa. All three sections show similar down-section variations in MS. Laboratory-based mineral magnetic measurements on sub-samples identified two major mineral magnetic zones (MMZB and MMZA). MMZB consists of coarser rained ferrimagnetic minerals and a larger proportion of anti-ferromagnetic haematite from spalling of the sandstone rock shelter during the arid, cold conditions of Oxygen Isotope Stage 4 (OIS 4). MMZA, which incorporates all layers from P1 (~60 ka) to BSV and BSS (~1100 AD), is dominated by fine- to ultra-fine-grained ferrimagnetic minerals (magnetite and maghaemite) that reflect the input of derived soils by aeolian activity. MMZA can be divided into three broad Climatic Zones (CZ3, CZ2 and CZ1) that reflect changes in the concentration of ferrimagnetic minerals during three age clusters. These are ~60 ka in OIS 4 and ~50 ka in OIS 3 and ~1100 AD in OIS 1. Optically stimulated luminescence (OSL) dating of the Middle Stone Age (MSA) sequence suggests hiatuses between the age clusters. Small-scale oscillations of MS in the sequence are thought to be due to varying amounts of intermixed anthropogenic material from hearths. Burnt material is identifiable by a unique mineral magnetic signature similar to that of burnt material from other archaeological sites in South Africa, but unlike that in other areas of the world. This is due to the long-term weathering and natural burning of the South African landscape. The transitional layers between OIS 4 (MMZB) and OIS 3 (MMZA) are associated with gypsum nodule formation that was probably post-depositional. It may have occurred during moister periods of climatic warming when no deposition took place in the Sibudu profile

Archaeomagnetic evidence for climate change at Sibudu Cave

In situ magnetic susceptibility (MS) measurements were undertaken on the north, south and east section walls of the trial trench in Sibudu Cave, KwaZulu-Natal, South Africa. All three sections show similar down-section variations in MS. Laboratory-based mineral magnetic measurements on sub-samples identified two major mineral magnetic zones (MMZB and MMZA). MMZB consists of coarser rained ferrimagnetic minerals and a larger proportion of anti-ferromagnetic haematite from spalling of the sandstone rock shelter during the arid, cold conditions of Oxygen Isotope Stage 4 (OIS 4). MMZA, which incorporates all layers from P1 (~60 ka) to BSV and BSS (~1100 AD), is dominated by fine- to ultra-fine-grained ferrimagnetic minerals (magnetite and maghaemite) that reflect the input of derived soils by aeolian activity. MMZA can be divided into three broad Climatic Zones (CZ3, CZ2 and CZ1) that reflect changes in the concentration of ferrimagnetic minerals during three age clusters. These are ~60 ka in OIS 4 and ~50 ka in OIS 3 and ~1100 AD in OIS 1. Optically stimulated luminescence (OSL) dating of the Middle Stone Age (MSA) sequence suggests hiatuses between the age clusters. Small-scale oscillations of MS in the sequence are thought to be due to varying amounts of intermixed anthropogenic material from hearths. Burnt material is identifiable by a unique mineral magnetic signature similar to that of burnt material from other archaeological sites in South Africa, but unlike that in other areas of the world. This is due to the long-term weathering and natural burning of the South African landscape. The transitional layers between OIS 4 (MMZB) and OIS 3 (MMZA) are associated with gypsum nodule formation that was probably post-depositional. It may have occurred during moister periods of climatic warming when no deposition took place in the Sibudu profile

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

Palaeomagnetic analysis was conducted on speleothems from Members 1–5 at Sterkfontein Cave, South Africa. Palaeomagnetic analysis of siltstone and speleothem from the bulk of Member 4 indicate a reversed magnetic polarity that dates the deposits and its Australopithecus africanus fossils to between 2.58 and ∼2.16 Ma. Further confirmation of this age comes in the form of two short normal polarity events correlated to the Rèunion (∼2.16 Ma) and Huckleberry Ridge (∼2.05 Ma) events in speleothem capping the bulk of Member 4 and coeval with deposition of the final phase of Member 4, including A. africanus fossil Sts 5. At ∼2.16–2.05 Ma, Sts 5 is the youngest representative of A. africanus yet discovered. Palaeomagnetic analysis of the Silberberg Grotto deposits identifies a single short geomagnetic field event in flowstone overlying the StW 573 Australopithecus fossil, which is suggested to represent the Rèunion event at ∼2.16 Ma. This further supports the uranium lead age estimates of 2.3–2.2 Ma for the StW 573 fossil. Based on a reversed polarity for the deposits below the skeleton it cannot be older than 2.58 Ma. If StW 573 is considered to be a second species of Australopithecus then this indicates that two species of Australopithecus are present at Sterkfontein between 2.6 and 2.0 Ma. All of the Member 5 deposits date to less than 1.8 Ma based on a comparison of palaeomagnetic, faunal, and electron spin resonance age estimates. The StW 53 fossil bearing infill (M5A) is intermediate in age between Member 4 and the rest of Member 5 (B-C) at around 1.78–1.49 Ma. The rest of Member 5 (B-C) containing Oldowan and Acheulian stone tools and Homo and Paranthropus fossils was deposited gradually between 1.40 and 1.07 Ma, much younger than previously suggested

Reconstructing the depositional history and age of fossil-bearing palaeokarst: A multidisciplinary example from the terminal Pliocene Aves Cave Complex, Bolt's farm, South Africa

The region ∼40 km north-west of Johannesburg, South Africa, known locally as the Cradle of Humankind, is of global significance as the caves preserve Plio-Pleistocene faunal and early hominin fossils. Despite a long history of research, there is still a need to contextualise and date the remarkable collection of fossils. An important but understudied palaeontological site, Bolt's Farm, may provide a key to addressing this as it preserves a series of >20 separate eroded palaeocave remnants occurring across a 1 km length of hillside. This is in contrast to highly concentrated deposits representing a single site, as is the case at the majority of the sites in the region. Historically, a lithostratigraphic approach to South African palaeocaves made reconstruction and comparison within, and between, deposits difficult or impossible. Here, we present a sequence stratigraphic approach and simple facies model for three palaeocave remnants at Bolt's Farm collectively termed the Aves Cave Complex (ACC), and a chronology based on combined uranium lead (U-Pb) dating, of basal and capping flowstones, and palaeomagnetic analysis. Results indicate that these currently discrete localities, formed together from a single entry dating to the end of the Gauss Normal Polarity Chron between 3.03 and 2.61 Ma, making ACC one of the oldest directly dated fossil deposits in the Cradle. The ACC contains the earliest occurrence of a key biochronological species, Metridiochoerus andrewsi, in the region. This work reinforces the model that clastic sedimentation and flowstone precipitation do not occur concurrently in Cradle caves; rather their mutually exclusive formation is driven by allocyclic changes in hydroclimate. This research contributes to understanding how Bolt's Farm developed the unprecedented high density of palaeokarst observed today, by offering the first evidence that currently discrete localities were once connected as a single cave system