New Excavations at Umhlatuzana Rockshelter, KwaZulu-Natal, South Africa: a Stratigraphic and Taphonomic Evaluation

Abstract

Umhlatuzana rockshelter has an occupation sequence spanning the last 70,000 years. It is one of the few sites with deposits covering the Middle to Later Stone Age transition (~40,000–30,000 years BP) in southern Africa. Comprehending the site’s depositional history and occupation sequence is thus important for the broader understanding of the development of Homo sapiens’ behavior. The rockshelter was first excavated in the 1980s by Jonathan Kaplan. He suggested that the integrity of the late Middle Stone Age and Later Stone Age sediments was compromised by large-scale sediment movement. In 2018, we initiated a high-resolution geoarchaeological study of the site to clarify the site formation processes. Here, we present the results of the excavation and propose a revised stratigraphic division of the Pleistocene sequence based on field observations, sedimentological (particle size) analyses, and cluster analysis. The taphonomy of the site is assessed through phytolith and geochemical (pH, loss on ignition, stable carbon isotope) analyses. The results indicate a consistent sedimentological environment characterized by in situ weathering. The analysis of the piece-plotted finds demonstrates semihorizontal layering of archaeologically dense zones and more sterile ones. There was no indication of large-scale postdepositional sediment movement. We show that the low-density archaeological horizons in the upper part of the Pleistocene sequence are best explained by the changing patterns of sedimentation rate.

Making the Invisible Stratigraphy Visible: A Grid-Based, Multi-Proxy Geoarchaeological Study of Umhlatuzana Rockshelter, South Africa

“…Kaplan dated the sequence using radiocarbon dating (Kaplan, 1990). The dates were later recalibrated in OxCal using the southern hemisphere calibration curve (Bronk Ramsey, 1995;Sifogeorgaki et al, 2020). Additional Optically Stimulated Luminescence (OSL) dates were obtained for the Pleistocene sediments (Jacobs et al, 2008;Lombard et al, 2010).…”

“…In 2018 and 2019 a team from Leiden University, in collaboration with the KwaZulu-Natal museum, conducted small scale excavations aiming to better contextualize the archaeological finds (Sifogeorgaki et al, 2020). Three 50 × 50 cm 2 squares (L2A, L2B, L3A) were excavated until a depth of 2.04-2.40 m, exposing a new western profile (Sifogeorgaki et al, 2020) (Figure 3).…”

“…Umhlatuzana rockshelter, located in KwaZulu-Natal, South Africa (Figure 1), is a good case-study site to address questions related to the MSA-LSA transition. The site preserves an archaeological archive spanning the last 70,000 years (Kaplan, 1990;Lombard et al, 2010;Sifogeorgaki et al, 2020), covering the later part of the MSA as well as the LSA (and some more recent, Iron Age deposits deposits). This makes Umhlatuzana one of the rare sites that has a continuous occupation sequence covering the MSA-LSA transition, making it paramount to understanding the nature of the transition in the region (see overviews in Lombard et al, 2012;Mackay et al, 2014).…”

“…Highresolution geoarchaeological data proved to be of particular importance, since the Pleistocene deposits did not display clearly visible stratigraphic boundaries in the field. Recent work by the team has addressed this issue by using clusteranalysis on the 3-dimentional distribution of the archaeological materials (Sifogeorgaki et al, 2020), allowing the identification of distinct horizontal artifact density zones and disproving the suggestion of large-scale sediment movement (contra Kaplan, 1990).…”

“…The current study builds upon the study of Sifogeorgaki et al (2020) by taking a geochemical approach to better understand the visible and invisible variation within the sequence. It examines if more subtle changes in depositional processes and postdepositional environment can be detected through the combined application of several geoarchaeological analyses.…”