Nelson Bay Cave

The Nelson Bay Cave, including Hoffman's/Robberg Cave, Matjes River rock shelter located 14 km north of Keurboomstrand, and other smaller caves formed in the eroded cliffs of the Robberg Peninsula. Robberg Peninsula is 4 km long and is geologically composed of sandstones and quartzites of the Cape Supergroup. The peninsula's cliffs have erosional features caused by wave-cutting, differences in rock types, bedding, and other bedrock characteristics that have led to the formation of caves and notches. Nelson Bay Cave is located on the south-facing slope of the Robberg Peninsula in quartz-sandstone and quartzite deposits. The cave developed in a contact breccia found at the contact between Silurian Table Mountain Group quartzite and Cretaceous Robberg Formation of the Uitenhage Group quartzitic sandstone during a time when mean sea level was 14 – 20 meters (66 ft). The cave is eroded at the contact where overlying rocks are river-mouth deposits of the Uitenhage Group. Table Mountain Group soils in this area are characterized as being sand, low in pH, and low in plant productivity. Soils that developed from the Uitenhage Group deposits are variable and range from sandy loams to clay loams. The geological conditions of the cave have allowed for the preservation of archaeological material. == Excavation History ==

Initial excavations were carried out in 1964–1965 by Ray R. Inskeep, removing younger Later Stone Age deposits. The early excavations revealed evidence of pottery, sheep remains, human burials, stone tool artifacts, ochre fragments, and shell ornaments. Later excavations in the early 1970–1972 by Inskeep and Richard G. Klein exposed Middle Stone Age deposits and bedrock material, estimated to date to the late Marine Isotope Stage (MIS) 5. R. R. Inskeep continued excavations at the site till 1979. The cave was unofficially named the ‘Wagenaar’s Cave’, and unpublished documents referred to it as such. The cave was later referred to as the Nelson Bay Cave based on the official name of the path leading up to the cave, the Nelson Bay. Units from the basal unit till the pale brown loam are correlated to the interglacial and early glacial period; black loam I till the rubble horizon falls within the lower pleniglacial and inter-pleniglacial period; gray loam II till the BSBJ fall within upper pleniglacial and late glacial; and units from J till GAI fall within the Holocene. Early excavators determined the ages of stone tool industries to be between 70,000 and 10,000 years old by using radiocarbon dating from charcoal from the site and correlating evidence from other archaeological sites such as Boomplaas cave. The Howeisons Poort industry dated to the MSA; Early LSA stone tool assemblages dated between 50,000 and 20,000 years; the Robberg industry dated between 12,000 and 8,000 years old; and the Wilton industry began around 8,000 years ago. Recent studies have updated the dates of the Later Stone Age sequence of the cave using radiocarbon dating and Bayesian models. == Archaeological Finds ==

=== Lithic Artifacts === Nelson Bay Cave is recognized as a Stone Age archaeological site. The cave is well known for the Robberg Industry which was first described in detail at the cave and is named after the peninsula. The cave is primarily characterized by three stone tool industries including the Middle Stone Age, Howiesons Poort, and Robberg Later Stone Age Industries. Fossils of bird species include cape gannet (Morus capensis), albatros (Thalassarche sp.), cape cormorant (Phalacrocorax capensis), and African penguin (Spheniscus demersus). Additionally, Late Pleistocene hominin tracks have been found along the margin of the Paleo-Agulhas Plain including mammalian tracks (e.g., golden mole) along the Robberg Nature Reserve. Fossils found in earlier layers (from YGL to BSL) include those of Cape pangolin, black-backed jackal, Egyptian and water mongoose, brown hyena, Cape fur seal, quagga, warthog, giant buffalo, Grimm's duiker, hartebeest, wildebeest, giant alcelaphine, cape hare, and porcupine. Those that occur from the early LSA Robberg to the late Holocene Post-climax Wilton industry include Chacma baboons, rock hyrax, bushpig, cape buffalo, southern reedbuck, grysbok, and vaalribbok. Modern human remains are found during the Middle to Late Holocene units including water mongoose, sea elephant, bushbuck, blue duiker, and dolphins. == Paleoenvironments ==

The cave has evidence of human occupation dating back to 125,000 years ago, with occasional Middle Stone Age occupations and serves as an important site for the Robberg Later Stone Age industry. Additionally, the cave is located on the coast of the southern Cape and provides insights about the Paleo-Agulhas Plain (PAP). Sea Level Changes The coastline moved 100 km seaward, and the sea level dropped to 130 meters during the Last Glacial Maximum. The PAP was exposed during glacial periods and became increasingly covered toward the end of the LGM with increased sea levels. Vegetation Shifts The cave also shows vegetation changes during the late Pleistocene and Holocene. From 22 000 to 14 000 years extensive grasslands covered the coastal plateau in the Plettenberg Bay area. Bovid teeth found in the cave have been to show climatic and ecological changes. The presence of fish and marine mollusks has been used to infer the distance from the coast to the cave. == Significance of Nelson Bay Cave ==

Nelson Bay Cave shows a long and intermittent occupation of humans dating back to 125,000 years, allowing archaeologists to learn and understand early humans and their development over thousands of years. This includes seeing how their environment has changed, the different foods diets early humans had and how those changes, and seeing the development of tool technologies over millennia. The cave shows evidence of key environmental changes during the glacial and interglacial period, and sea level changes that have exposed and submerged the Paleo-Agulhas Plain. Records of these changes have been used to understand the climate and environmental changes at a larger scale and seeing how human populations have adapted to these changes. These adaptations have given rise to debates about the evolution of modern human behaviors. The first is the interpretation of the archaeological evidence found at the cave bringing into question technological and cultural practices of cave dwellers over centuries. These debates are based on four parts, the chronology and dating of the site, interpretation of the archaeological record, palaeoenvironmental changes, and the aspect of human adaptation and living strategies. Klein (1972) mentioned issues about the dating of the site, especially in layers that were dated based on their relativity to archaeological materials. Loftus et al. (2016) provided new radiocarbon dates filling in the chronological gaps between the Middle Stone Age and Later Stone Age, and highlighting the role of the cave during the MSA/LSA transition. This is coupled with the presence of cultural material found in the cave that shows complex cultural and social practices. Moreover, the adaptations have resulted in the rise of different stone tool technologies that have been significant for the Stone Age archaeological record of southern Africa. Where, the Robberg Industry was first described leading to the cave being recognized as a type-site for this type of technology. Lastly, during the first excavations burials were uncovered near the entrance of the cave, the remains being in a fetal position, and decorated with shells and ochre. These burials have been used to provide insight about burial practices and behaviors of modern cave dwellers. == Heritage Status ==

Nelson Bay Cave and the rest of the Robberg Peninsula fall within the Robberg Nature Reserve, a provincial heritage site monitored by Cape Nature. The Robberg Nature Reserve and Marine Protected Area was also declared a marine protected area by the Department of Environmental Affairs and Tourism in December 2000. In 1993, Janette Deacon and Michael Brett proposed a display area for the cave to preserve its integrity and avoid erosion and degradation. This proposed display included a brick wall to prevent the collapse of the east and west excavation walls and a siphon to catch water from cutting into the cave. Currently, a walkway leading to the site's display exists, showing an intact section profile from the original excavations and illustrations that tell the story of the cave. == See also ==