The Klasies River Caves are a series of caves located east of the Klasies River Mouth on the Tsitsikamma coast in the Humansdorp district of Eastern Cape Province, South Africa. The Klasies River Main (KRM) site consists of 3 main caves and 2 shelters located within a cliff on the southern coast of the Eastern Cape. The site provides evidence for developments in stone tool technology, evolution of modern human anatomy and behavior, and changes in paleoecology and climate in Southern Africa based on evidence from plant remains.
Site exposition Klasies River Cave is located on the border of the Tsitsikamma mountain range on the southeastern coast of Africa. The site sits within the Greater Cape Floristic region, characterized by the fynbos biome; however the Klasies River Cave environment is mixed woods and shrubby brushland and maintains a temperate climate. Klasies River main site is located on a sandstone cliff less than 1 kilometer from the Klasies River mouth and on the coast of the Indian Ocean. The district receives approximately 500–700 mm (20–28 in) of rainfall annually.
The site consists of Caves 1 and 2, and the protected overhangs of Cave 1A and 1B, together known as Klasies River main site. However, Cave 2 was not accessible until later stages after there had been significant deposition and build-up of sediments, and Cave 1B has been under-documented; most finds therefore come from Caves 1 and1A. These caves contain 21 meters of deposits that researchers have struggled to delineate stratigraphically. While sea levels fluctuated over time, during certain occupations, the proximity to the coast and the surrounding grasslands provided marine life and terrestrial animals that were exploited by the caves inhabitants.
Excavations From 1967–1968 John Wymer and Ronald Singer conducted excavations that revealed evidence of Middle Stone Age (MSA)-associated human habitation beginning approximately 125,000 years ago. Singer and Wymer excavated Caves 1, 1A and 1B, and part of Cave 2; using culture stratigraphy, they determined stages as MSA I, MSA II, Howiesons Poort, MSA III and MSA IV, which allowed comparison across the caves. Critiques of the original excavation include sampling bias due to excavation and screening methods, and combination of stratigraphic layers that obscures the sites' complexity; certain strata were lumped together making it difficult to differentiate between activities at the site and combining artifacts and bones from multiple different strata.
These initial findings prompted successive excavations to examine the varied and complex stratigraphy. Hilary Deacon began work in Caves 1, 1A and 1B from 1984–1995 focusing on the arbitrary delineation (the "Witness Baulk") that Singer and Wymer used to differentiate Cave 1A from Cave 1, as these caves are actually continuous. While the Singer and Wymer excavation used units that were excavated uniformly across the cave layer by layer, successive excavations focused on different stratigraphic approaches. Deacon's excavations maintained the microstratigraphy of the site. Deacon excavated units one by one, independently of other units in the cave, recording the stratigraphy observed in each individual unit before grouping units together based on their shared stratigraphic patterns. Rather than use culture stratigraphy, Deacon used a hybrid strategy combining Singer and Wymer's culture stratigraphy and lithostratigraphy. He developed a descriptive naming pattern for the observed soils instead of Singer and Wymer's classification system, however both systems are still used today.
Sarah Wurz began directing excavations at the site in 2013 and continues today with a continued focus on microstratigraphy; her work is mainly within the Cave 1 Witness Baulk, a section that hadn't been excavated previously. The current work is focused on gathering data from the microstratigraphy and refining the process of micro-scale excavations. This data allows comparison of KRM to other sites across the continent.
Stratigraphy and dating The dates of the KRM stratigraphy have been obtained through isotopic analysis and dating of biological materials. Because the site exceeds 50,000 years old, radiocarbon dates are less useful due to carbon contamination. Researchers have resorted to analysis of unstable isotopes, such as Uranium-Thorium (U-Th) to provide more accurate date ranges. Marine isotope stages (MIS) are used to compare large-scale global temporal comparisons; each stage in the Klasies River Caves site correlates with a MIS stage.
The stratigraphy of the site consists of very fine, thin layers of sediment that have compressed under the successive layers on top of them. Researchers have used microstratigraphic techniques to analyze and interpret the complex timeline of sediment deposition and post-depositional activities within the caves. Because the cave system has so many varied layers and the different caves have different depositional characteristics and sediment properties, it has been hard to create a uniform system to group and chronologically group the layers for a site-wide comparison; natural processes such as erosion, and the influence of people at certain areas of the site (anthropogenic deposition of shell middens, hearths, etc.) have further complicated the interpretation of the stratigraphy. A lithostratigraphic and culture stratigraphic approach are both used at KRM today.
Singer and Wymer's stages at KRM began at the base, MSA I, followed by MSA II, Howiesons Poort, MSA III, and MSA IV. These groupings are based on changes on stratigraphy and/or changes in material culture though time. Deacon chose to organize the site based on soil descriptions; he categorizes the site on this basis with the lowest level being Basal Gravels, followed by the Light Brown Sand (LBS) Member, the Rubble Brown Sand (RBS) member, the Shell and Sand (SAS) member, the Rockfall (RF) and Upper member, and the White Sand (WS) member. Some of these layers are then further subdivided. This system allows researchers to compare deposition patterns and contexts across the site in each cave which may have different dates because of differing deposition processes in each cave environment; some caves may not contain each member listed. +Singer and Wymer's Culture-Stratigraphic AssociationDeacon's LithostratigraphyDate rangesMarine isotope stageDating method and locationMSA IVWhite Sand (WS) Member70 ka MIS 4optically stimulated luminescence dating (OSL) and infrared stimulated luminescence dating. Dating material from Cave 1 and dates earlier than in Cave 1A.MSA IIIUpper Member60–43 kaMIS 4 / MIS 3linear uranium uptake model electron spin resonance (LU ESR) and TL dating. Dating material from Cave 1A.Howiesons PoortUpper Member65–45 kaMIS 4LU ESR, U-Series, and OSL dating. Dating material from Cave 1A.MSA IIShell and Sand (SAS) Member104–36 kaMIS 5d-aLU-ESR and U-Th shell dating in Cave 1. *in Cave 1A, the MSA II dates from 80-28 kya based on Uranium-Thorium and OSL dating within the same layer. This correlates with the Rockfall (RF) Member described by Deacon.MSA ILight Brown Sand (LBS) Member110–90 kaMIS 5d/eAmino Acid Racemization (AAR), U-Th, and TL-OSL dating.
Paleoenvironment Paleoenvironment reconstruction uses multiple analytical foci to help determine a proximate estimate of the climate of a site during a given time frame. These reconstructions are aided through archaeological excavations and finds. Analysis of faunal remains can indicate what species existed across space and time. Likewise, archaeobotanical analysis provides insight into the plants that were in proximity to the site. These determinations are also aided by global climate estimates provided by deep sea cores. Plant and animal remains can also be indicative of certain climates as species have certain climatic ranges and preferred biomes. Changes in the location of the sea shore and in the grassy or wetland areas surrounding the cave have been determined using these methods.
MSA I fauna indicate a mosaic environment that included closed, drier areas with micromammals including moles, and open grasslands that favored grazing ungulates. This period is associated with an interglacial period (MIS 5e) and higher sea levels and warmer temperatures, which is supported by shell middens.
MSA II shows a shift from MSA I. This period is associated with MIS 5d-a, with the early part of this phase associated with warmer temperatures shifting towards cooler temperatures later. During this time the coastline was likely never more than 10 km away from the site. The number of grazers decreased while mixed-feeders and browsers increased; this correlates with a decrease in shrubland and expanding grasslands. Terrestrial fauna include rock hyrax (rock rabbits), brown hyena, Cape dune mole rat, buffalo, equids, and members of the subfamily Alcelaphinae. There is also evidence of forest-dwelling bovid and other animals that prefer wetland grasses and reeds (African marsh rat and hippopotamus), indicating the environmental diversity of the site during MSA II. Warm-water shellfish (brown mussels and other rocky shore species) and cape fur seals were present at the cave as groups were able to exploit marine food sources as well.
The Howiesons Poort (HP) environment shifts from the closed environment of the later MSA II into a more open environment featuring more grazing animals. The earlier levels of HP contain more evidence of browsers which indicate a more closed environment while later periods increase in grazing fauna associated with more open environments. This period is associated with MIS 4, a glacial period with cooler temperatures and lower sea levels. Shellfish that appear in tide pools are more common in HP which suggests a further coastline. Data from Pinnacle Point show that the climate during HP was variable and unstable with periods of drought.
MSA III is marked by a declining temperatures and receding coastline that would have exposed the Palaeo-Agulhas Plain. The faunal remains are variable and consist of wetland species, open environment grassland grazers, and Cape dune mole rats that prefer sand dunes. This period corresponds to MIS 3, a cooler environment with short warm periods.
There is little data available to describe the paleoecology of the MSA IV. It does not contain many archaeological features such as hearths or material culture other than lithics.
Current ethnobotanical research exploring the biodiversity of Klasies River and the Cape region found that many hunter-gatherer-pastoralists from the Khoi and San populations use the flora and fauna of the region that was also found in archaeobotanical and faunal assemblages. The study took an inventory of plants within 5 km of the modern Klasies site and discovered 268 species. Over 50% of these plants were medicinal and 43% were edible or had other uses as demonstrated from interviews with Khoi and San communities. While not all of these plant species may have existed during the Middle Stone Age, these findings still demonstrate the longevity of plant knowledge throughout the communities in the area. The study also noted that the use of certain plant types for survival during climate changes, and proposed that humans in the past could have subsisted in similar ways.
Findings
Material culture