THE ROCK ART OF WESTERN CENTRAL AFRICA

	HUMAN SETTLEMENT IN THE MIDDLE OGOOUE VALLEY	Page 7/10

During the long dry period, the Maluekian (see below), which lasted from 70,000 to 40,000 B.P., many of the central African forests gave way to savannas (Roche 1979). During this period, brutal but infrequent rainstorms caused severe erosion, which deposited large quantities of stones, pebbles, and gravel in riverbeds. Peoples of the middle Stone Age lived close to these rivers, using the stones to fashion rough tools, including the choppers, picks, and scrapers of the Sangoan industry, which are common in riverbanks and around ancient lakes in central Africa. These industries tend to occur in flood-plain deposits, which are by nature very disturbed and remain poorly understood. The following period, the Ndjilian, from 40,000 to 30,000 B.P., was humid and favorable for forest growth (Caratini and Giresse 1979) but very few human remains are known from this period. From 30,000 to 12,000 B.P., equatorial Africa suffered a severe drought, the Leopoldvillian climatic phase, when forests were restricted to river galleries and moist mountain ranges (Maley 1991). Sea level was more than 120 m below its current position, revealing vast beaches, which were molded by the wind into dunes along the coasts of Equatorial Guinea, Gabon, and Congo. Sporadic rains again caused severe erosion, washing away clay and sand layers and revealing the base rock. Rising rivers carried stones and pebbles, which accumulated in the middle terraces, about 10 m higher than they are today. Hunter-gatherer peoples of this Lupembian period lived on hilltops close to water and made more sophisticated stone tools. Their throwing weapons, made out of stone collected from numerous rock deposits, suggest that they were living in an open savanna environment in which visibility was good. One finds these industries at the top of alluvial deposits, but to date there is no site in central Africa of known stratigraphy to provide a chronological reference for the Maluekian, Ndjilian,or Leopoldvillian period (Lanfranchi 1990).

Chronological references (Years)	Industry	Palaeclimate periods	Major events
Present	Late Iron Age (800 BP to present)	Kibangian B (3,500 BP to present)	Forest Expansion Humid Phase (from 2,000 BP)
500
1,000	Hiatus (1,400-800 BP)
1,500	Early Iron Age (2,500-1,500 BP)
2,000
2,500			Dry Phase (3,000-2,000 BP) Savanna Expansion Anthropic Influence
3,500	Neolithic Stage (4,500-2,500 BP)		Humid Phase Forest Expansion
4,500		Kibangian A (12,000-3,500 BP)
10,000	Tshitolian Complex (12,000-4,500 BP) Late Stone Age
30,000	Lupembian Complex Middle Stone Age	Leopoldvillian (30,000-12,000 BP)	Dry Phase Savanna Expansion
40,000	?	Ndjilian (40,000-30,000 BP)	Forest Expansion Humid Phase
70,000	Sangoan Complex Stone-line Industry	Maluekian (70,000-40,000 BP)	Dry Phase Savanna Expansion
120,000	?	Pre-Maluekian (Eemien Stage)	Humid Phase

Around 12,000B.P., in the Kibangian period, the earth became warmer and the climate moister, and once again forest colonized the savanna, sea level rose, and large areas of mangroves developed. Humans of this period made small tools, or microliths, from stone and demonstrated their improved technology with the advent of the bow and arrow. Remains from the late Stone Age are much more abundant than those of the middle Stone Age and include the well-known Tshitolian industry. These comprise many sites along the valley of the Ogooue (Oslisly et al 1994), as well as on either side of the lower course of the Congo River on the Teke Plateau and the Kinshasa plain in the Democratic Republic of Congo (Cahen and Mortelmans 1973), in the Niari Valley, Congo (Bayle des Hermens and Lanfranchi 1978) and the north of Angola (Ervedosa 1980). These hunter-gatherers lived mostly on hilltops in savanna areas but also inhabited caves and rock shelters. Remains from the late Stone Age are occasionally found within the sandy-clayey layer above the stone line, which tends to be 1-2 m deep in the middle Ogooue region when it is present at all (in many places this layer has been eroded away). Within this layer, stone industries have been dated to between 9,000 and 6,000 B.P., placing this soil formation in the Kibangian. All late Stone Age sites in the middle valley of the Ogooue are located on hilltops, principally in savanna but sometimes on the forest crest lines, with the Leledi 10 site dated at 5,700 B.P. (Oslisly and White). They often appear as large eroded patches in the savanna, visible on aerial photographs, and in many areas erosion has washed away all remains. It seems that this erosion process, which is ongoing, began during a climate change in the Kibangian B (3,500-2,000 B.P.; Maley 1992). These late Stone Age industries evolved from the Lupembian industry, which was characterized by small hand axes, picks, large arrowheads, core axes, and scrapers, but which also developed smaller, lighter tools called microliths. Their improved technology, which belongs to the Tshitolian complex, would have allowed the hunter-gatherers of the time to become more mobile than their ancestors. During the late Stone Age, large areas of stone fragments accumulated where tools were fashioned, and these are often visible today as patches of erosion. Neolithic and Iron Age peoples dug refuse pits, and Iron Age peoples also built furnaces to extract iron from ore. What landscape did these peoples live in? This question is difficult to answer, but a site that we have named Lope 2 (Oslisly 1993a) gives some useful pointers. This site has unusually well preserved stratigraphy, with three layers of charcoal, the first two of which are associated with numerous flakes and stone tools made from milky quartz and jasper (Oslisly et al. 1996): • Layer 1, between 30 and 40 cm, is dated to 6,760 B.P.
• Layer 2, between 60 and 70 cm, is dated to 9,170 B.P.
• Layer 3, between 100 and 110 cm, is dated to 10,320 B.P. Charcoal in these layers has been identified as belonging to Diogoa zenkeri and Strombosiopsis tetrandra (both Olacaceae), two species characteristic of mature rain forest in the region (Tutin et al. 1994). Analyses of levels of isotopic indicate that savanna vegetation dominated down to 50 cm depth (c. 8,000 B.P.), but samples from 60-120 cm (c. 9,000 B.P. and older) gave values that were intermediate between forest and savanna (see Schwartz et al. 1986 for an explanation of this method). Hence these hunter-gatherer peoples lived in an open landscape of forest-savanna mosaic and chose to live on a hilltop. They are likely to have fed on plants collected from within the forest, certainly hunted meat with bows and stone arrow-heads, and used the wood of forest trees for their fires. → Africa Rock Art Archive
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