LSA lithic assemblages from Laga Oda
An investigation of Later Stone Age lithic assemblages from Laga Oda rock shelter, Southeastern Ethiopia
By Seminew Asrat
Seminew Asrat has been laureate of the CFEE 2021 Grant and has defended his MA thesis in Archaeology at Addis Abeba University, Department of Archaeology and Heritage Management, under the direction of Worku Derara and Clément Ménard, in October 2021. He is actually conducting a PhD research at ‘La Sapienza’ University of Rome. His MA research work is here brightly summarized. If not mentioned, all pictures are from him.
Stone tools are the earliest, most ubiquitous, and the most enduring archaeological records of the past population (Andrefsky, 2005). Lithic artefacts and their manufacturing debris constitute the bulk of evidence and invaluable insights for archaeologists into past human life and activities, resources utilization strategies, behaviour, technology, and economy (Goodale & Andrefsky, 2015; Tryon, 2013).
The Laga Oda rock shelter stands among the key sites in Ethiopia yielding evidence of LSA lithic assemblages. Over the years, researchers working in Ethiopia have long been emphasizing on the documentation of the Early and Middle Stone Age rather than the Late Stone Age cultural sequence (Sahle, 2020). The same holds true for the Laga Oda rock-shelter, where despite an initial preliminary report (Clark & Williams, 1978) and stratigraphic and technological section description by Kurshna (1978), a more detailed and state-of-the-art techno-typological and attribute analysis of lithic assemblages have remained limited. Despite its relevance to issues of neolithization and subsequent human occupation of the region, a detailed description of the occupational sequence and the material record retrieved from occupation layers revealing the economic lifeways of the occupants of the site is far from complete. Similarly, previous studies did not compare intra-site and inter-site stratified occupations to understand variations and/or uniqueness of LSA technologies in time and space. Thus, this study examined the LSA lithic assemblage (n=563) to obtain insights into the behavioral, technological, subsistence, and occupation nature of prehistoric populations of southeastern Ethiopia.
The Laga Oda rock-shelter is situated geographically at 09.50 08 24° N and 41.67 74 04° E with an elevation of 1658m asl. It is located at the edge of the southeastern Ethiopia plateau about 25 km southwest of Dire Dawa (fig. 1). The shelter is located facing west above the Oda stream and is known by the locals as ‘Goda- Kataba’ which means a cave with written records. Laga Oda has two rock shelters, one above the other, in a limestone cliff facing the south (fig. 2). The site is one of the few relevant excavated sites that supplement the repertoire of our knowledge on the origins of food production although the rest of the evidence from rock art sites is inherently circumstantial.
The Laga Oda site was discovered in 1933 by F.B. Azaïs and Oncieu De Chappardon. A more detailed exploration of Laga Oda was carried out in the 1970s (Clark & Prince, 1978), as part of the archaeological exploration of the area conducted under the leadership of J.D. Clark (University of California, Berkeley) (Clark & Willimson, 1978; Kurashina, 1978). The rock shelter is a two-story limestone formation known for its spectacular rock arts and LSA lithic assemblages. The paintings exhibit most dominantly animals and human representations such as horned cattle, fat-tailed sheep, and humans (Clark & Prince, 1978). The site of Laga Oda is stratigraphically defined and securely dated radiometrically. Dating the charcoal recovered from the 1975 excavation in this site has provided five dates ranging from 15,000 to 300 years BP (Clark & Williams, 1978).
Methodologically, identification and analysis of techno-typological attributes of lithics artefacts were conducted at the Authority for Research and Conservation of Cultural Heritage (ARCCH) laboratory. Dimensions of each artefact were measured using an electronic digital calliper. Profile of representative lithic specimens within the LSA assemblages from Laga Oda was drawn and enhanced digitally using adobe-photoshop to show details on the edge, dorsal and ventral sides of the specimens (fig. 3). The minimum and maximum dimensions of each tool class and attribute parameters were measured. Comparisons of lithic assemblages from Laga Oda were made with other LSA sites of Goda Buticha and Mochena Borago sites which are dated to the Middle and Late Holocene period from previously published sources.
Our study revealed various distinct typologies of LSA artefacts with retouch and none-retouch elements including flakes, cores, flake fragments, backed pieces, scrapers, denticulate, and burins. In the assemblages, pottery, beds, and teeth remains were also analyzed. Evidence of lithic artefacts was recovered up to 140 cm depth reflecting the presence of human occupation from the terminal Pleistocene to the Late Holocene time. Most of the assemblages were recovered from the archaeological horizon situated between 20 and 60 cm below the datum. The presence of artefacts at all stratigraphic levels shows a sequence of sporadic human occupations with similar technological and typological traits.
The technological and typological evaluation of these LSA lithic assemblages has offered us information on the lithic reduction techniques during the Late Upper Pleistocene and Holocene periods. Typologically, the Laga Oda site assemblages are dominated by backed pieces, despite both retouch and non-retouch pieces of different typologies (fig. 4).
In terms of the raw materials, cherts were utilized exclusively most likely of local origin. The rock shelter is situated within chert-bearing rock outcrops. The availability of chert sources close to the site suggests the importance of economical utilization of local resource procurement strategies. Other raw materials such as obsidian, quartz, limestone, and jasper had been used to a minimum extent. Obsidians and other raw materials indicate those materials could have been imported from distant areas.
Though the sample size is small, the majority of the bladelets from Laga Oda were recovered from 40-70 cm units of strata. This suggests an early stage of production during the Middle to Late Holocene compared to the backed pieces produced during the Late Holocene. However, this should be tested with large sample size and with more investigations in the future. Bladelets analysis reflect they were produced by the laminar production technique as is indicated from flake scares, elongated blanks with parallel ridges (fig. 5).
Core rejuvenation flakes are ubiquitous, representing a type of preparatory bladelet removal before the desired blades were removed from the core. From technical pieces and crested bladelets, a series of prismatic bladelet production with the preparation of the face of the core could be inferred (fig. 6).
To understand the technological aspect, analysis involving several attributes of the assemblages was conducted. Striking platform analysis of flakes shows that the plain and punctiform platforms have been dominated the majority of the flake and bladelet assemblages. Punctiform or point platform suggests the possibility of using a soft hammer or indirect percussion. The lithic technology and morphologies of the assemblages suggest production techniques might have involved multiple types of percussions including bi-polar, hard hammer, soft hammer as well indirect percussion.
Scrapers from this site are larger in size which suggests its utilization without hafting. The few burin spalls show the burin production technique that might have been employed at Laga Oda. Burin spalls have often been associated with preparation for hafting purposes like engraving activities on the wood of bladelet/blade tools to be mounted into organic materials.
Particularly, the study revealed backed pieces (n=203) are the most significant portion of the whole assemblages retaining unique technological and typological features (fig. 7). The dimensions and other attributes analysed, suggest the presence of a pretty consistent and standardized manufacturing strategy in the backed pieces. Consistency in size and forms of backed elements have been inferred from Laga Oda.
The attribute analysis of backed pieces including the curvature, butt, twisting, and others indicates stone tool manufacturing processes might have involved the use of the soft hammer technique. Likewise, the technological production of curved pieces has been observed with a high frequency at Laga Oda. The analysis of flake and backed pieces butts indicates that punctiform platforms types dominated the assemblages.
The backed tools of Laga Oda could have been hafted onto wooden handles used possibly for cutting grasses, leaves, vegetables, and other materials. Scholars argued that the association of lithic morphology with their function has become questionable (e.g., Anderfsky, 2005). At Laga Oda, however, use-wear and lithic experimental analysis (Clark, 1978) revealed that backed pieces were mounted and used for processing plant remains. Likewise, our investigation indicates the presence of fire traces on many of our assemblages.
Comparisons have been made with other contemporaneous sites of Goda Buticha (southeastern Ethiopian) and Mochena Borago (southwestern Ethiopia) (Leplongeon, Ménard, Bonhomme, & Bortolini, 2020). The comparisons of Laga Oda backed pieces with the two contemporaneous sites revealed both similarities and variations in technological and typological aspects of the LSA assemblage during the Middle and Late Holocene. More cultural affinity has been observed with Goda Buticha. This could be due to the geographical proximity between the two sites which were also believed to be occupied by pastoralist prehistoric communities. Similarities in retouching and reshaping techniques were for example employed during tools modification. Backed pieces in all the selected assemblages are dominantly directly curved. Other common features of backed pieces from the three sites are removed butt, absence of bulb continues backing of back location, no edge transformation, and sharp edge angle.
From the material culture distribution, the composition of the assemblage (mainly backed pieces), the rock art, and other assemblages, pastoralist subsistence strategies may have been practised by these prehistoric communities. The rock shelter and the eastern side of the rift escarpment may also have acted as a sporadic refuge area for the environmental and climatic fluctuation that happened during the MIS-1.
Other associated archaeological materials such as pottery sherds, faunal remains (teeth), ochre, and mastic were also reported from this site. Thirteen ceramic sherds with non-diagnostic features have been documented. Similarly, evidence of human teeth – three molars and one canine – have been documented. To understand the implication of human remains from the Laga Oda site, sufficient data is required in the future so that one can describe the dietary adaptation and subsistence behaviour of the prehistoric society in this region. The presence of beads in the archaeological record is an important indicator of symbolic behaviours and ornamentation. The earliest evidence of beads in Ethiopia was reported from the site of Porc Epic during the MSA time dated between ∼33 and 143 ka (Assefa, Pleurdeau, Duquesnoy, & Hovers, 2008).
Studies on the use and exploitation of ochre during the MSA and LSA have been documented very well from Southern Africa sites. The exploitation of ochre as a mastic has been studied from many MSA and LSA sites in eastern African (Ambrose, 1998). In Ethiopia, ochre-stained grindstones have been reported from the LMSA sites of Aduma (Yellen et al., 2005) and Porc Epic cave (J. Clark, Williamson, Michels, & Marean, 1984). The presence of ochre at Laga Oda might have been used as a possible pigment for the execution of pastoral rock art and adornment. This is also discussed and supported by the experimental work of Clark and Prince (1978) from the same site of Laga Oda. Certainly, these pieces suggest the presence of direct associations with the rock arts of the Laga Oda rock shelter as a possible pigment although geochemical analysis remains to be done to offer a clear association between them.
I would like to acknowledge the Authority for Research and Conservation of Cultural Heritage (ARCCH) for providing us with the required research facilities and access to the Laga Oda collections. Financial support to this research has been provided by the French Center for Ethiopian Studies (CFEE) and the School of Graduate Studies of Addis Ababa University.
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