International Journal of Innovative Research and Knowledge Volume-3 Issue-7, July-2018

INTERNATIONAL JOURNAL OF INNOVATIVE RESEARCH AND KNOWLEDGE ISSN-2213-1356 www.ijirk.com

ARCHAEOLOGICAL AND ENVIRONMENTAL HISTORY OF THE CENTRAL RIFT VALLEY OF

Dr. Ben N. Nyanchoga

Abstract This paper is a product of archaeological field research that was carried out in the Central Rift Valley of Kenya. The Central Rift valley of Kenya is key in understanding the prehistory of East Africa. Some of the earliest human technological and cultural developments can be traced to this region. The Central Rift is sandwiched between the to Southwest and the Aberdare ranges to the North. The region has provided insurmountable information on the palaeoecology and archaeological literature of the Central Rift Valley of Kenya. This paper discusses the archaeological and environmental history of the Central Rift Valley of Kenya making reference to potential sites.

Keywords: Pleistocene; Volcanic tuff; Volcanic ash; Palaeo-lithic; palaeo-environment; palaeo-ecology

Introduction The Central Rift valley of Kenya is strategic in understanding the history of Pleistocene landscape of East Africa. It occupies a special position in the study of East African prehistory. The area is rich in environmental history as it home to variety of biodiversity, Pleistocene lakes and unique landforms. It is also postulated that the Central Rift valley of Kenya is one of the earliest centers of human evolution as there exists many archaeological sites dating to the Early Stone Age period.

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The volcanic tuff, Lake Sediments, and caves lying in the region contain many unmapped and undiscovered archaeological sites. Most importantly, volcanic ash characteristic of the area has aided in the preservation and dating of archaeological remains spanning millions of years ago. The Central Rift and specifically the - Elmentaita basin contains key archaeological sites like Kariandusi (Paleolithic/Stone Age site), Gambles Cave, , Lanet among others. Gambles, Hyrax and Lanet are all Late Stone Age sites. Archaeological and palaeontological studies in the Central rift begun with Louis Leakey in the early 1930s, who was later joined by his wife and fellow palaeontologist Mary Leakey. Since then a series of researches have been conducted in the area that is rich in archaeological information.

Palaeoenvironment and Palaeoecology of the Central Rift The interpretation of the East African palaeoenvironment was originally based on the pluvial theory (Leakey, 1931) which itself was based on stratigraphic deposits with pluvial and interpluvial periods. Climate change in East Africa caught the curiosity of early explorers in the latter part of the 19th century and it continued to be the subject of investigations up to the 1980s (Hastenrath, 1984; Nicholson, 1998, 1999). Lake level measurements, historical accounts, observation, and analysis of glacier variations in the tropics are an indicator of this climatic change. East Africa experiences rain between March and June with its core around April to May. The Eastern Rift Valley was formed by plate tectonic processes on a global scale (Leakey 1931; Ambrose, 1984b, 2003:97). Tectonic uplift raised the East African region 1500m above sea-level during the Middle Pleistocene. This was accompanied by fissure eruption of flood basalts and volcanic mountains within the Rift Valley which created several lake basins, for example, , Elementaita and Nakuru.

The Central Rift Valley is located at the highest point of uplift on the East African dome. From East to West across the Rift Valley the main topographic features are the Nyandarua Range, an elongated North-South trending mountain chain, 400m from a base level of 2400m on the . The Rift floor in the Naivasha basin is about 30km wide and is bounded by the Mau escarpment on the west, which rises to 3100m (Ambrose 1984b, 2003:98). The widespread evidence of tectonic deformation in the Naivasha-Elementaita and Nakuru basins has certainly influenced both the sedimentological and hydrological history of the region. In its narrowest segment, vegetation grades from open grasslands through savannah woodlands up through various forest types to Alpine Meadows. The bottom of the valley is dotted with a series of lakes including, from North to South, Baringo, Bogoria, Nakuru, Elmenteita and Naivasha (Gifford-Gonzalez and Kimengich, 1984: 457). Rapid oscillations of lake levels with amplitudes of 60-190m are likely to have been largely climatically determined. During this time precipitation could have been at least 65% greater than at present in the case of the Nakuru-Elementaita basin and 50% in the case of the Naivasha basin (Butzer et al., 1972).

The Nakuru-Elementaita basin is bounded by Mt. Eburru to the South and Mt. to the North. The basin outlet was through the Menengai caldera. The basins of Lakes Naivasha, Elementaita and Nakuru have received greater attention from palaeo-environmentalists than any other areas of comparable size in Eastern Africa. The three lakes lie just south of the equator at a point where the floor of the Eastern Rift Valley reaches its greatest elevation. is the largest (though nowadays it has reduced considerably) and freshest, while Lakes Elmentaita and Nakuru are smaller, shallower and highly saline. Lake Naivasha was four times its present area and stood about 58 metres above the present shoreline (Butzer et al., 1972; Richardson 1966; Richardson and Richardson 1972; Washbourn-Kamau 1967, 1970, 1975). Figure 3.2 shows the flactuations of Lake Naivasha since the 1800s.

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Fig 3.1: Lake levels of Elmenteita, Nakuru and Naivasha during the Early Holocene Source: Adapted from Butzer et al. 1972

Fig. 3.2: Flactuations of Lake Naivasha since the 1800s Source: Modified from Nicholson 1996

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The modern potential outlet of the Nakuru-Elmentaita basin stood at 1949m which was 191m above the modern level of which stood at 1758m. Two raised shorelines could be traced in the basin. The older of this, the Gamble’s Cave shoreline, was represented by prominent shoreline notches and lithoral deposits along the outer slopes of Menengai crater, on the Karterit volicanic cone and at Gamble’s Cave, the lake level stood at 180m and the enlarged lake is believed to have seeped into the Menengai Crater .The shoreline dates to 10,000- 8000BP. In Naivasha basin, a possible beach ridge and the presence in many places of beach gravels indicate that the lake stood at 2000m compared to the 1972 level of 1890m. The lake overflowed into Njorowa Gorge the floor of which then stood at a higher level than its present day altitude of 1940m-1950m (Butzer et al., 1972; Richardson 1966; Richardson and Richardson 1972).

Lakes of the Nakuru-Naivasha depression are most sensitive to climatic change and are surrounded by several sets of strandlines of known geologic age. Radiocarbon dating and uranium-thorium have shown that high water levels correspond generally to times 6000 to 10000, 23000 to 27,000 and 90,000 years ago when world glaciers were relatively small. Strand lines give a reasonable record of times when the water level was high, but times of low water level are registered only in the sediments, often as unconformities, gaps in deposition due to periods of non- deposition, erosion or weathering (Livingstone, 1996:10). Plate 3.1 shows Lake Nakuru and an expanding human settlement in the middle ground.

Plate 3.1: Lake Nakuru as viewed from the summit of the Hyrax Hill prehistoric site

In understanding the palaeoenvironment and palaeoecology of the region indicators of climate, vegetation and faunal communities are key.

Climate The factors which pattern ecological relationships in tropical areas are more complex and subtle, generating communities with diffuse boundaries and complicated interrelationships. The diversity and flexibility of cultural adaptations in East Africa reflect these uncertainties, both today and in the past, making it difficult to generalize about the adaptive economic behaviour of even a single society in the absence of detailed, longitudinal studies. Climatic changes have undoubtedly produced subtle, but pervasive effects in the ecology of human adaptations. In arid and semi-arid zones of East Africa, temperatures are continuously warm to hot and little variation occurs

www.ijirk.com Page 230 International Journal of Innovative Research and Knowledge Volume-3 Issue-7, July-2018 throughout the year (Swift et al., 1996:246). It is also probable that the development and diversification of pastoral and agricultural adaptations have produced cumulative, irreversible changes in many regional environments, necessitating complex adaptive readjustments which have changed the basic character of human adaptations from time to time.

The two most important features of climate are rainfall and temperature (de Voos, 1975:21). The author states that temperature is strongly influenced by the altitude of the land surface and to some extent the same is true of rainfall, for the higher areas tend to have a high rainfall. These elements form a climate pattern that together with the soil type determines vegetational zones or ecosystems (Morais, 1988:15). Subtropical pressure areas situated about 20-300 North and South of the Equator are important controls of the climate of tropical Africa (Boucher, 1975). The sub-tropical high pressure cells tend to move North during the Northern Summer and South during the Southern Summer, and the outflow of air from their centres is reducing during Summer months as a consequence of thermal heating. The North-East Trade Winds, which blow out from the North African and Arabian high-pressure cells are very dry and often laden with dust.

According to Boucher (1975), rainfall data from East Africa indicate that most rains occur during the passage of the Inter-Tropical Convergence Zone (ITCZ) (Boucher, 1975). The ITCZ is the low pressure zone where the North-East and South-East trades converge and is characterized by conventional rainfall. There are variations related to latitude, but the causes of the complex pattern are poorly understood (Kensworthy, 1966).

Spatial variability of rainfall is a key feature of the regional climate variation. Spatial variations in rainfall are obviously significant to animals and pastoralists who move about in response to spatial distributions of pasture. Rainfall is spatially patchy, particularly over short time scales. Convective storms and highly localized rain showers are quite common. In general, rainfall increases with elevation. The driest areas of East Africa are those located at low elevations, such as the floor of the Rift Valley. Topography produces rainfall gradients within landscapes and regions (Swift et al., 1996:299)

According to Ambrose (1984b:9), the Naivasha-Elementaita-Nakuru basin is located within one degree South of the Equator and lies within the ITCZ. The prevailing winds are from the East and North-East. Mount Kenya and the Nyandarua Range capture most rainfall from the monsoons and cast a significant rain shadow over the Central Rift, particularly over the Naivasha basin. Ambrose (1984b:10) further arguesr that in the South and East of Mt. Eburu there is usually a cool overcast dry season from May to September and a hot dry season from December to March. This bimodial pattern is much muted in the Naivasha basin and only the hot dry season persists in the Nakuru basin. All these dynamics of climatic changes have a strong effect on the distribution of vegetation zones and human adaptations in the area.

Vegetation Vegetation is one of the key indicators of the general environment. Perring (1959) expressed this idea in terms of the following formula: V=f(Cl,p,r,o,t), i.e., vegetation characteristics (V) are a function of regional climate (Cl), soil parent material(p), topography (r), organisms (including available flora) (o) and time (t). There are various ways of classifying vegetation, usually involving a variable mixture of floristic and physiognomic characteristics. Physiognomy refers to the general appearance of vegetation while physiognomic attributes include height, structure, plant density and leaf size.

Vegetation of the dry semi-arid zones is physiognomically diverse. Grasslands are grass dominated ecosystems with shrub and tree covers of less than 2%. Dwarf shrubs (often less than 70cm tall) are mixed with herbaceous plants to form dwarf shrub grasslands. Shrub grasslands and wooded grasslands have a woody cover of less than www.ijirk.com Page 231 International Journal of Innovative Research and Knowledge ISSN-2213-1356

20%. In a ‘shrubland’, the woody plants do not exceed 6 metres in height but their cover exceeds 20 %. ‘Woodland’ is comprised of plants greater than 6 metres in height with cover in excess of 20 %. A ‘forest’ has a closed 100% cover, multilayered canopy of trees 7 to 40 metres tall. All these plant physiognomies can be found in the dry climatic zones of East Africa (Swift et al., 1996:247).

Classification of vegetation based on floristic composition can be very valuable since within a confined area the distribution of species is believed to be largely determined by variations in environmental factors. Ambrose (1984b:13) notes that floral zonation in the Rift Valley is controlled by a complex combination of factors including rainfall, temperature, slope, soil drainage, soil nutrient availability and herbivore predation on plants. Vegetation physiognomy is often related to water availability which is affected by soil texture, direct rainfall and water redistribution on the landscape. Woody canopy cover on sites not subsidized by run-on is roughly correlated with mean annual rainfall. Water- subsidized sites are likely to support more woody cover and larger trees. Where water is concentrated into ephemeral stream beds it infiltrates to a depth that is beyond the rooting zone of herbaceous plants (Swift et al., 1996:248). The nature of vegetation in the Naivasha-Elementaita-Nakuru basin is of the following categories.

• Dry savanna type –This occurs in even drier areas. It is characterized by smaller and more widely spaced tree or shrubs and a lower grass stratum.

• Moist savanna type –characterized by a single stratum of densely spaced trees with relatively large leaves or leaflets and herbaceous stratum of tall, narrow-level grasses. This type is found in areas with less effective rainfall than forest zones (Ambrose 1984b:14).

It is important to note that the composition of vegetation species and structure is strongly influenced by soil, elevation, drainage and mediation of landforms (Van Rooyen, 2001). The relevance of regional ecological evaluation of vegetation and soil types in relation to ancestral agricultural practices is crucial. This is because there is a close relationship between vegetation, soils and local land use systems (see, for example, Morais, 1988:27).

Faunal communities Within the area of study there is a high density of mammalian herbivore communities which have existed since time immemorial. The forest, bush and savanna biomes each have highly diverse though contrasting herbivore communities with little overlap in species composition except for the largest common species such as buffalo, elephant and rhino. In general the most abundant grassland and open woodland animal forms are large, nomadic or migratory grazers and mixed feeders (Ambrose, 1984b:16).The social territorial characteristics of forest herbivores contrast with those of open habitats. Jarman (1974) argues that forest herbivores are usually solitary, have smaller home ranges and small body sizes.

Environmental and archaeological information of the sites The Nakuru-Naivasha region is today considered prime ranchland, and archaeological evidence attests to heavy reliance on domestic stock in the area at least 3000 years ago (Richardson and Richardson, 1972). Early sites yielding remains of domestic stock, namely caprines and Bos taurus, have been referred to as the ‘Pastoral Neolithic’ by archaeologists working in the area (Bower et al., 1977). There appears to be at least two industrial variants in this area. Sites in more open countryside yield numerous geometric microliths, small scrapers, larger heavy duty tools, ground stone axes, bowls and ceramics. According to Wandibba (1977), some pottery types are decorated with typical patterns of motif execution and placement while others are not. These pottery types belong to the Savannah Pastoral Neolithic (Ambrose, 1984b). www.ijirk.com Page 232 International Journal of Innovative Research and Knowledge Volume-3 Issue-7, July-2018

In a more closed environment of the Mau Escarpment West of Lake Naivasha, sites lying in forested regions as well as montane meadows have yielded different lithic assemblages characterized by long blades (Gifford- Gonzalez et al., 1984:458). The sites under investigation lie in the central stretch of the Kenyan Rift Valley (see Fig 3.4). The sites investigated by early researchers during different times have yielded considerable archaeological data. Table 3.1 shows the environmental summary of the sites studied while Table 3.2 shows rainfall variation in the Naivasha region between 1999 and 2008.

Table 3.1: Environmental summary of the sites Environmental Hyrax Hill Crescent Island Njoro River Cave Gambles’ cave parameter Altitude Ca. 1900m Ca.1900m Ca.2000m Ca. 1800m Mean annual 765mm-1016mm 254mm-508mm 735mm-980mm 762-1016mm rainfall Mean: 890.5mm Mean: 381mm Mean: 857.5mm Mean: 889mm

0 0 0 0 Temperature Min: 10-14 C Min: 10-14 C Min: 6-10 c Min: 10-14 C 0 0 0 0 Max: 26-30 C Max: 26-30 C Max: 18-22 c Max: 26-30 C 0 0 0 Mean Min: 8 c 0 Mean Min: 12 c Mean Min: 12 c Mean Min: 12 c 0 0 0 Mean Max: 20 c 0 Mean Max: 28 c Mean Max: 28 c Mean Max: 28 c

Vegetation Wooded grassland Wooded grassland Forest Wooded grassland Source: Adapted from Gramly, 1975:60

Table 3.2: Rainfall variation in the Naivasha region between 1999 and 2008 Naivasha Rainfall Data (mm) Month Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Mean Total

Year

1999 19.5 29.3 96.9 62.9 16.1 13.3 12.3 98.3 13 39.8 8.56 43 44.16 529.9

2000 9.8 1.9 27.8 55.5 8.9 10.8 27.6 8 16.6 108.6 45.2 20.3 28 336

2001 128.5 1.5 102.9 84.2 11.5 17.5 45 31.9 76.9 58.4 64.9 22.4 53.8 645.6

2002 67.8 0 121.5 174.1 140 21.4 15.8 39.2 35.2 73.3 97.7 131.1 76.43 917.1

2003 37.5 8.6 21.2 113 211.1 78.5 30.7 102.3 41.5 73.6 25.8 27.6 64.28 771.4

2004 29.8 62.1 113.6 182.4 31.9 23.3 7.6 30.7 33.4 27.9 79.1 30.1 54.33 651.9

2005 49.8 24.7 42.9 101.1 103.1 22.9 32.2 38.3 85.5 109.2 31.9 3.5 53.76 645.1

2006 0 25.8 121.2 140.8 44.7 19.9 13.3 125.5 19.3 33 173.1 119.9 69.71 836.5

2007 26.2 73.5 32.3 86.7 60 81.8 27.2 22.6 49.9 30.9 26.2 30.7 45.67 548

2008 5.8 57.1 151.7 68.4 67.8 9.1 26.4 15.7 81.2 70.7 32.1 4 49.97 590

Source: District Commissioner’s Office, 2010

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The sites and Geographical settings Crescent Island site The Crescent Island site lies on an island with the same name in Naivasha. The site lies at an altitude of about 1900m. Its rainfall variability ranges between 254mm and 508 mm annually. The temperatures range from 10-14 degrees Centigrade and 26-30 degrees Centigrade for mean annual minimum and mean annual maximum, respectively. The characteristic vegetation type in the area is wooded grassland (Gramly, 1975).

According to Onyango-Abuje (1977:72), Crescent Island was completely surrounded by water and it would not have been possible to reach it except by boat. With fluctuations of the lake levels, however, it must at times have been possible to walk to the island through a natural causeway on its southern end. It is possible that both man and animals made use of the natural path to the Island during dry spells similar to those common today in the Rift Valley.

Crescent Island has a semi-arid environment. Conditions in this arid savanna are drier and vegetation adapts accordingly. Its natural vegetation consists of dry forms of woodland and savannah acacia, for example, Themeda acacia. Generally acacia dominates the Island. The Island is also covered with isolated thorn-bushes and Succulents are common especially on the shores of the Lake (Plate 3.2). The western shore of the Island has a fairly established papyrus growth (see also Gakahu et al., 1996:27)

Plate 3.2: A section of Crescent Island that was excavated in 1975 and 1976 with the survey beacon in the foreground and Lake Naivasha in the background

The site was excavated by J.C. Onyango-Abuje in 1975 after R.M. Gramly had done soundings there (Wandibba, 1977:22). A total of three trenches, one of them through a cairn, were excavated. The excavation was done in arbitrary 10cm-spits and the soil sieved through a 3mm screen. The archaeological materials recovered included stone bowls, pestle rubbers, grindstones, polished stone axehead and lithic materials. Faunal remains included a hippo tooth and several animal bones. Some of the bones were identified as being of cattle and sheep/goat. Pottery materials were also recovered from the site, most of it being undecorated (Wandibba, 1982). Wandibba further

www.ijirk.com Page 234 International Journal of Innovative Research and Knowledge Volume-3 Issue-7, July-2018 states that other sections of the site were excavated by the University of Massachusssets Archaeological Group in East Africa between December 1975 and June 1976. The site has been given a date of between 2795 +_155BP and 2405+_150 BP (Onyango-Abuje, 1977:24).

Gamble’s Cave Gamble’s cave is located in a high bluff overlooking the Nderit River a few kilometres from where the Elmenteita-Nakuru road crosses the river. The cave is wave- cut in poorly consolidated tuffs (Wandibba, 1977:13). The area is characterized by wooded grassland vegetation. Rainfall variability is high. Grass is often tall, especially in open areas. There are a few acacia trees which qualify locally as woodland. Montane acacia vegetation is characteristic of the area. Examples of such acacia types are Abyssinica and Polyacantha (Langdale- Brown et al., 1964).

The site was excavated by L.S.B. Leakey between 1926 and 1929 (Leakey 1931) and re-excavated by Glynn Isaac and Ron Clarke in 1964 (Bower et al., 1977). It is the type site of the Elmenteitan and the ‘Kenya Capsian’ industries. The Upper Kenyan Capsian in aggregates of which crescents form a dominant part was initially defined on the basis of the sequence at Gamble’s Cave. Leakey named three successive phases, A-C. A is the earliest industry present at the site. Phase B coincides with the peak of workmanship in the knapping of obsidian. Phase C declines in standard of workmanship. All these phases have aggregates containing backed blades, crescents, burins and end scrapers, associated with ostrich eggshell beads and bone points. Above the Kenya Capsian C at Gamble’s Cave was a thick layer of rock debris with a few hearths around which were scattered artefacts (Leakey, 1931).

When the site was excavated by Leakey, fifteen stratigraphically distinct deposits were recognized of which the upper five contained enormous quantities of sherds together with faunal remains, beads, pendants, human burials, and stone tools. The lowest sherds, stratigraphically, were negligible in number and frequency and were most probably introduced through the excavation of burial pits or animal burrows (Leakey, 1931). During the 1964 excavation, lithic artifacts, predominantly microlithic fragments, unshaped tools, side and notched scrapers and outils e’cailles were recovered (Wandibba, 1982).

Hyrax Hill site Hyrax Hill is a prominent site located 3 km East of Nakuru town centre. It consists of a narrow rock spur measuring 500m from North to South, and dates to 2800-2000 years ago. It rises nearly 50m above the surrounding plain and commands a good view of the escarpments to the east and west and Menengai crater towering above it to the Northwest and the saline edge of Lake Nakuru 4 km to the South (Sutton, 1987).

The site lies at an altitude of about 1900m above sea-level. The mean annual rainfall ranges between765mm- 1,016mm per year. The temperatures range between 10-14 degrees Centigrade for the mean annual minimum and 26-30 degrees Centigrade for the mean annual maximum. The vegetation type in the area is wooded grassland (Gramly, 1975).

Hyrax Hill appears to have been formed as a result of rifting and volcanism. Volcanic activities that occurred in the Central Rift Valley created varied topographies, with forested volcanic mountains, grassy plains, escarpments, thicket-covered lava flows, and closed lake basins that are often alkaline. The Hill, which roughly assumes a dome-shaped landform, represents one of the many forms of volcanic mountains in the region. Volcanic rocks which predominates the Eastern Rift Valley are strewn all over the Hill. The Hill is covered with a fairly well established vegetative growth. It presents itself as an open over story of trees and/or shrubs and a ground layer of

www.ijirk.com Page 235 International Journal of Innovative Research and Knowledge ISSN-2213-1356 grasses (Personal observation). The dominant vegetation in the area consists of grasses in the understory (see Plate 3.3).

Plate 3.3: A picture of Hyrax Hill showing shrubs, sparsely vegetation growth, and an understory of grasses

Hyrax Hill was investigated in the 1920s by Louis Leakey (Sutton 1998:82). Leakey noticed archaeological remains on both sites of Hyrax Hill (Sites 1 and II) in 1926 when he was excavating the Nakuru burial site. Accompanied later by his wife Mary in 1937, they excavated the rough stone enclosures on Site 1. The cultural materials recovered included stone tools, pottery and faunal remains (Sutton, 1998:83).

The Neolithic occupation and burials of Site 1 to the South-east side of the Hill was also investigated by Mary Leakey in 1937. Some limited follow-up work was undertaken by R.J. Clarke for the Kenya Museums in 1965, and more extensive excavations by J.C. Onyango-Abuje in 1973 and 1974. The initial purpose of Mary Leakey’s excavation was to investigate the visible stone enclosures and hut circles, which Louis Leakey had assumed were dwelling places of the ‘Neolithic’ population responsible for the Nakuru Burial Site. That supposition was mistaken, for the enclosures and connected features were later found to belong to the Iron Age (Sutton, 1998: 86).

However, Mary Leakey identified the remains of the ‘Neolithic’ burial mound, consisting of a broad but rather low ‘stony structure’ from what she called an occupation layer below it. In the burials accompanying some of the bodies were shallow stone bowls and stone pestles. While the stone bowls were made out of volcanic lava, the pestles were made from quartz, quartzite and gneiss which are foreign to the Nakuru area, an indication that people carried them from a distance of about one hundred kilometres far away (Sutton, 1998:88). Other materials that came from the occupation layer included obsidian tools (predominantly crescents and backed blades) and a collection of pottery.

Site II was excavated by Mary Leakey in 1938. This section consisted of Sirikwa `hump and hollow’ features which indicated a pre-iron age settlement. Mary Leakey called the hollows `pits’ on the assumption that they represented ancient pit dwellings (Sutton, 1998:95). The associated mounds were regarded as `middens’ or rubbish dumps. The materials recovered from this section were also in form of stone tools, pottery and fauna (Sutton, 1998:98). www.ijirk.com Page 236 International Journal of Innovative Research and Knowledge Volume-3 Issue-7, July-2018

In Mary Leakey’s excavation report, this Site (Site 11) is called ‘the North-East Village’, on the assumption that each hollow had once contained a house and that all were in use together. The Sirikwa hollows were used by pastoral communities for keeping cattle, goats and sheep (Sutton, 1998:99). Notably, there were accumulated mounds adjacent to the hollows. The mounds were as a result of daily dumping of dung and mud which were scooped from the hollow. Domestic refuse including food bones and broken pots were also discarded on those mounds. Since there were no permanent water sources around hyrax Hill with its porous soils, it may be that this site and the surrounding pastures were preferred in the wet season. In an extended dry season the nearest water may have been that of the Njoro River (Sutton, 1998:99)

Archaeological remains at the Hill are associated with recent pastoralist wares and iron technology. The cultural remains of the Neolithic occupation consisting of implements of waste flakes, potsherds, pestles and broken animal bones and teeth, were all derived from an almost stoneless stratum of brown loamy soil which averaged 0.3 m thick and covered a considerable area (Wandibba, 1977:19).

Njoro River Cave Njoro River Cave is in the elevated section of the Central Rift Valley about 1.6 km upstream from Egerton University. The Njoro River Cave site lies at an altitude of 2000m above sea-level, well above all the other sites. Its rainfall variability ranges between 735mm and 980mm annually. The temperatures for the area ranges between 6 and10 degrees Centigrade for the mean annual minimum and 18-22 degrees Centigrade for the mean annual maximum (Gramly, 1975) .

The environment around Njoro River cave is characterized by a mid-elevation rain forest ecosystem. It is located at the western edge of the Central Rift Valley near the base of the Mau escarpment. The region where the site lies receives a lot rain due to its proximity to the Mau escarpment. Njoro River is the main water source in the area and this might have been the main attraction to the pastoral people besides pasture (Young, 1996:389).

Despite the human activities like farming and timber production, the forest cover in the region is fairly dense. The term ‘rain forest’ is defined as a forest that is evergreen hygrophilous (moisture loving) in character, at least 30m high, rich in thick-stemmed lianas and in woody as well as herbaceous epiphytes (Young, 1996:390). The area is home to a large number of endemic plants predominantly evergreen to semi-deciduous trees, a few small game animals and provides watershed maintenance. It is also important in maintaining the stability of long-term climatic patterns, and contains vital resources such as firewood, building materials and medicinal plants (Young, 1996:398). Due to forest cover the soils in the area are wet as a result of high water content compared to other sites in the Central Rift.

The cave is famous for its cremated burials of about eighty individuals accompanied by obsidian tools, grindstones and pestles, pottery, beads, pendants, objects of wood, basketry and gourd. Archaeological research at this site started with Mary Leakey in 1938 when she excavated the cave. At the time of excavation a total number of adult remains corresponded almost exactly with the number of stone bowls (79), pestles (78), and lower grindstone (77) ( M.D.Leakey 1938). The pestles and grindstones were presumably used for grinding ochre.

The dominant stone tools were blades characteristic of the Elementeitan culture. Many of these showed extensive use. Njoro River Cave is undoubtedly the most interesting Pastoral Neolithic site in East Africa. Besides its uniqueness as a crematorium, it has provided the finest series of stone bowls, pestles as well as pendants. Beads from other East African sites are very rare and are generally thought to have been imported. The large number

www.ijirk.com Page 237 International Journal of Innovative Research and Knowledge ISSN-2213-1356 found at Njoro, and the fact that all material used for their manufacture exist in Kenya, makes it probable that they were made locally (Cole, 1963). Figure 3.4 shows the main archaeological sites in the Central Rift.

Fig.3.3: The Central Rift showing the main archaeological sites. (Source: Modified from Sutton, 1998:75)

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