Turkana Area Research Articles

The Burden of Cystic Echinococcosis in Kenya: A Review Article

Cystic echinococcosis (CE), caused by the larval stage of Echinococcus granulosus sensu lato (s.l), is a zoonotic parasitic disease with a worldwide distribution. Kenya is one of the high endemic countries of CE with the endemic areas in the country being under immense occupation of traditional pastoralists. Turkana area in Kenya, has in the past recorded the highest prevalence of CE in the world. The keywords cystic echinococcosis; Prevalence; Diagnosis; Risk-factors; Kenya were searched on google scholar and PubMed and the important literature materials retrieved for further analysis. The most notable infection risk factor for this disease in the country is the close association between man, dogs, and livestock. Successful control of CE in Kenya requires application of innovative interventions achieved after the review of the disease situation in the country. With the emergence and advent of new diagnostic techniques, CE organ-specific infections and transmission pattern in Kenya differ from what is commonly reported in literature. A better understanding of CE prevalence of different hosts, its transmission pattern and the pathogenicity might make it possible to set up more effective control programs in future.

Continuous improvement of laboratory quality systems through upper management support: Lodwar county referral hospital (LCRH), Kenya experience

Pliocene and Pleistocene sediments from West Turkana (Kenya, East African Rift System) form emblematic syn-rift successions for understanding the evolution of extensional basin and continental rifting. They also constitute world-renowned fossil-bearing strata from which >500 hominin fossils were discovered over the past decades, with >100 inventoried archeological sites. However, associated sedimentary dynamics and architectures as well as paleoenvironments are only partially reconstructed and the relative contribution of climate and tectonism to paleoenvironmental change over time remains unclear. Here, through the interpretation of sedimentary facies, the delineation of sequences and the analysis of δ13C in soil carbonates, we provide the first exhaustive reconstruction from ~4.00 to ~0.75 Ma of (i) fluctuations of the paleolake that occupied the Turkana Depression, (ii) the successive sedimentary dynamics and related paleolandscapes that characterized the West Turkana area and (iii) respective roles of climate and tectonism in the sedimentation. We show evidence for seven major transgression-regression (T-R) cycles between ~4.00 and ~ 0.75 Ma superimposed locally by lower amplitude T-R cycles. Comparing the sedimentological interpretations and the δ13C values in soil carbonates (literature data), we reveal that fluctuations of rainfall over the Ethiopian Dome, which hosts the drainage basin of the Omo River — the main tributary of Lake Turkana — controlled high-amplitude lake level fluctuations during the Plio-Pleistocene period. We also demonstrate that vegetation and tree cover evolved differently in the Omo Valley and West Turkana. Furthermore we outline that two different sedimentary systems reflecting two distinct modes of sedimentation alternated through times in the West Turkana area as a response to the variations in sediment supply coming from the western rift shoulder (i.e. Lapurr Range) that alternatively generated wave- or river-dominated sedimentary systems. In conclusion, we reveal that climate regulated water input, paleolake water-level fluctuations and vegetation. Tectonism determined sediment supply to the basin controlled in West Turkana by pulses of increased activity of the main border fault (i.e., the Murua Rith Lapurr Fault).

Early Pliocene anuran fossils from Kanapoi, Kenya, and the first fossil record for the African burrowing frog Hemisus (Neobatrachia: Hemisotidae)

Isolated amphibian bones from the early Pliocene of Kanapoi (West Turkana, Kenya) help to improve the scarce fossil record of the late Neogene and Quaternary amphibians from East Africa. All currently available 579 bones are referable exclusively to the Anura (frogs and toads). More than half of the remains (366) are identified as Hemisus cf. Hemisus marmoratus, an extant species that still inhabits Kenya, but apparently not the northwest of the country and the Turkana area in particular. The rest of the remains are identified simply as Anura indet. because of poor preservation or non congruence with the relatively few African extant taxa whose osteology is known in detail. The Hemisus material represents the first fossil record for Hemisotidae, an endemic African family of peculiar, head-first burrowing frogs, whose sister taxon relationships indicate a divergence from brevicipitids in the Late Cretaceous or early Paleocene. The ecological requirements of extant H. marmoratus suggest that the Kanapoi area surrounding the fluvial and deltaic settings, from where the fossil remains of vertebrates were buried, was likely a grassland or relatively dry, open low tree-shrub savanna.

Stepwise drying of Lake Turkana at the end of the African Humid Period: a forced regression modulated by solar activity variations?

Abstract. Although the timing of the termination of the African Humid Period (AHP) is now relatively well established, the modes and controlling factors of this drying are still debated. Here, through a geomorphological approach, we characterize the regression of Lake Turkana at the end of the AHP. We show that lake level fall during this period was not continuous but rather stepwise and consisted of five episodes of rapid lake level fall separated by episodes marked by slower rates of lake level fall. Whereas the overall regressive trend reflects a decrease in regional precipitations linked to the gradual reduction in Northern Hemisphere summer insolation, itself controlled by orbital precession, we focus discussion on the origin of the five periods of accelerated lake level fall. We propose that these periods are due to temporary reductions in rainfall across the Lake Turkana area associated with repeated westward displacement of the Congo Air Boundary (CAB) during solar activity minima.

Orbitally-driven evolution of Lake Turkana (Turkana Depression, Kenya, EARS) between 1.95 and 1.72 Ma: A sequence stratigraphy perspective

Lakes act as major archives for continental paleoenvironments, particularly when the evolution of lake levels over time serves as a guide for understanding regional paleohydrology and paleoclimate. In this paper, two sections from the Nachukui Formation (Turkana Depression, East African Rift System) provide a complete record of lake level variability and then paleohydrology for Lake Turkana between 1.95 and 1.72 Ma. This period corresponds to a key time during which important human evolutionary and technological innovations have occurred in East Africa and in the Turkana area. Based on sedimentary facies and sequence analyses on coastal deposits, one long-term regressive-transgressive cycle is identified between 1.95 and 1.72 Ma. Superimposed on this trend, five higher-frequency cycles of lake level change are identified between 1.87 and 1.76 Ma. Origins of these periodicities are attributed to orbital forcings. The extents of bathymetry change and shoreline migration during these periods are explored, suggesting that the period between 1.87 and 1.76 Ma was relatively dry and that climate experienced a relatively low variability. This finding differs strongly from most of the previous paleoenvironmental investigations in the region that argue high climate variability during a relatively wet period. This work emphasizes the importance of using sequence stratigraphy for analyzing lacustrine deposits.

From Elmolo to Gura Pau: A remembered Cushitic language of Lake Turkana and its possible revitalization

This article discusses the “extinct” Elmolo language of the Lake Turkana area in Kenya. A surprisingly large amount of the vocabulary of this Cushitic language (whose community shifted to Nilotic Samburu in the 20th century), far from being lost and forgotten, is still known and is, to a certain extent, still used. The Cushitic material contains both specialized vocabulary (for the most part related to fishing) and miscellaneous and general words, mostly basic lexicon. It is this part of the lexicon that is the basis of recent revitalization efforts currently undertaken by the community in response to the changing political situation in the area. The article describes the Cushitic material still found among the Elmolo and discusses the current revitalization efforts (in which the author has, albeit marginally, taken part), pinpointing its difficulties and uncertain results. The article is followed by a glossary listing all the Cushitic words still in use or remembered by at least a part of the community.

Stratigraphy, sedimentology and diagenetic evolution of the Lapur Sandstone in northern Kenya: Implications for oil exploration of the Meso-Cenozoic Turkana depression

The northern Turkana region of northwestern Kenya forms the intersection between two major rift systems in Africa, the Cretaceous–Paleogene Central African Rift System (CARS), and the eastern arm of the Paleogene–Present East African Rift System (EARS). The southern Sudanese oil-rich rift basins form part of the CARS, and their extension into the Anza Rift in northeastern Kenya makes the area of northern Turkana an important target for oil exploration. Limited past exploration activity in the area leaves the study of surface outcrops as the main avenue for understanding the reservoir potential of the fluvial deposits of these rift systems. The outcrops of these potential reservoirs, collectively referred to as “Turkana Grits” in the past, are represented on the western side of Lake Turkana by the Lapur Sandstone in the north, and by other grit formations in the central and southern parts of the basin. Isotopic age determinations on the basal parts of the “Turkana Volcanics” that overlie the Lapur Sandstone have enabled the precise dating of the upper parts of the LS at between 35 and 37Ma, while the lower part of the formation near the contact with the underlying Precambrian basement is estimated as Upper Cretaceous (Turonian–early Campanian), based on the discovery of dinosaur and other reptilian fauna. Detailed lithological logging, coupled with subsequent petrographic and sedimentological studies, have enabled the determination of the depositional environments and the diagenetic evolution of the Lapur Sandstone. The basal and uppermost parts of the formation are interpreted as distal alluvial fan environments possibly connected to the last stages of rifting characterizing the Central African Rift System. The middle part of the Lapur Sandstone corresponds to a wide braided fluvial system that can be compared to fluvial episodes of Late Cretaceous age in the Sudan region, associated to major palaeogeographical changes in northern Africa. The nearly abrupt disappearance of the Lapur upper fan system relates to the deposition of the “Turkana Volcanics” from Late Eocene, possibly as a consequence of the emplacement of the Afar Plume at 45–35Ma. In terms of diagenesis, the main cement material at the base of the Lapur Sandstone is calcite, whereas at the middle of the formation, hematite becomes the dominant cement, and at the topmost section, kaolin cement dominates. The diagenetic evolution of the sandstones has been favourable to the retention of adequate primary intergranular porosity and the creation of secondary intragranular dissolution porosity, mainly through feldspar dissolution, and thus preserving the reservoir potential of the Lapur Sandstone. The reservoir characteristics, such as the porosity and cementation style, of the Lapur Sandstone are comparable to those of the fluvial sandstone reservoirs of the southern Sudan oil fields and this should positively contribute to the overall petroleum potential of the northern Turkana region. Though the northern Turkana area has remained largely unexplored, it is hoped that the demonstration of the presence of reasonably good reservoir quality sandstones in the Lapur Sandstone will serve to encourage further interest in hydrocarbon exploration in the Turkana area.

Obsidian types from Holocene sites around Lake Turkana, and other localities in northern Kenya

Obsidian has been widely used by early Holocene hunter-gatherers and succeeding Pastoral Neolithic peoples in northern Kenya. Here we report the results of over 2000 electron microprobe analyses of artifactual and non-artifactual obsidian from the greater Lake Turkana region. Of the 15 compositional types of obsidian observed, a preponderant type is widespread across the region from the Barrier in the south to Ileret in the north and east as far as Kargi. This obsidian is the principal type at Lowasera and most Pastoral Neolithic sites, including the Jarigole Pillar site and Dongodien (GaJi4). The source of this obsidian is not known, but based on its distribution the source may be located on the Barrier or in the Suguta Valley immediately to the south of Lake Turkana. Although there are several possible sources of local obsidian identified for minor types, in stark contrast to the central part of the Kenyan Rift, major sources of obsidian available for artifact manufacture are not known in the Lake Turkana region. The lack of obsidian from demonstrable Ethiopian Rift and central Kenyan Rift sources, and the absence of obsidian with compositions found at the Turkana area sites in assemblages in the central part of the Kenyan Rift suggests that the earlier Pastoral Neolithic peoples around Lake Turkana interacted with each other, but perhaps not as strongly with people farther south along the Rift Valley, even as herding practices were expanding to the southward into central Kenya.

Emerging resource use conflicts between Kenyan fishermen, pastoralists and tribesmen of Lake Turkana

Frequent droughts over the years causing partial or total loss of livestock caused the community to take up fishing in Lake Turkana as an alternative activity for survival. The objective of the study was to get baseline information on the socio-economic situation in Lake Turkana area. Survey revealed that in recent years there have been increased incidences of insecurity and cattle rustling, which has driven more pastoralists into fishing. Most respondents indicated they were primarily fishers, followed by pastoralists. Most fished in the shallow inshore areas using mainly gillnets and purse seine nets. The greatest concern of the fishers is the conflict with the tribesmen of southern Ethiopia. The fishing offers an opportunity for the pastoral communities to settle down to a sedentary lifestyle, making it easier to access health, educational and other essential services. Women are also involved, though in low numbers, some of whom own boats and gears. Currently, fishery resources in offshore areas are unexploited, but there is a need to control pressure in inshore shallow areas.

Tertiary Mafic Lavas of Turkana, Kenya: Constraints on East African Plume Structure and the Occurrence of High-μ Volcanism in Africa

The East African Rift System is important to understanding plume-initiated rifting as manifest in the geochemistry of mafic lavas erupted along the rift throughout its evolution. We present new data from high-MgO Tertiary lavas from Turkana, northern Kenya, to investigate regional melt source components, to identify the depths and degrees of melting, and to characterize spatially and temporally the chemical structure of the underlying mantle. The Turkana area is a region of high lithospheric extension that sits between two topographic uplifts thought to be surface expressions of one or more upwelling mantle plumes. Thinning of local crust is believed to be accompanied by widespread removal of the mantle lithosphere, causing the asthenosphere to be in close contact with the overlying crust. New geochemical data on basanites, picrites and basalts (MgO >7 wt %) tightly constrain the primary melt source regions of Tertiary volcanism. Initial isotopic signatures (143Nd/144Nd = 0·51267–0·51283, 87Sr/86Sr = 0·7031–0·7036) and trace element abundances (Ce/Pb ∼30, La/Nb = 0·6–0·8 and Ba/Nb = 3–10) in these lavas are consistent with derivation from sub-lithospheric sources. Basalts and picrites erupted between ∼23 and 20 Ma have Sr–Nd–Pb–He isotopic characteristics indicative of high-μ influence, record high depths and degrees of partial melting, and are associated with rift propagation to the north and south. Accordingly, these lavas sample a source region that is geochemically distinct from that reflected both in Oligocene Ethiopian flood basalts and in the modern Afar region. The geochemical data support numerical and theoretical models as well as tomographic results providing for a complex thermal structure in the mantle beneath East Africa and are interpreted to reflect isotopically distinct plume heads beneath Tanzania and Afar that are derived from the chemically heterogeneous South African superplume.

Lake Turkana Archaeology: The Holocene

Pioneering research in the Holocene archaeology of Lake Turkana contributed significantly to the development of broader issues in the prehistory of Africa, including the aquatic civilization model and the initial spread of domesticated livestock in East Africa. These topics are reviewed following retrospective discussion of the nature of pioneering fieldwork carried out in the area in the 1960s. The early research at Lake Turkana uncovered the oldest pottery in East Africa as well as large numbers of bone harpoons similar to those found along the Nile Valley and elsewhere in Africa. The Lake Turkana area remains one of the major building blocks in the interpretation of the later prehistory of Africa as a whole, just as it is a key area for understanding the early phases of human evolution.

Dynamics of prolonged continental extension in magmatic rifts: the Turkana Rift case study (North Kenya)

Abstract The Turkana magmatic rift (Northern Kenya) initiated at 45 Ma as one of the nucleation zones of rifting in the East African Rift. It forms an anomalously broad-rifted zone ( c. 200 km) striking with a north-south trend and lying within a NW-SE topographic depression, floored on both sides of the Turkana area by Cretaceous rifts in the Sudan and Anza plains. From a compilation of available data, combined with newly acquired remote sensing and DEM dataset, we propose a five-stage tectono-magmatic model for the Turkana rift evolution (45–23 Ma; 23–15 Ma; 15–6 Ma; 6–2.6 Ma and 2.6 Ma-Present). The corresponding ‘restored’ maps clearly show the changing spatial distribution of magmatism and fault/basin network with time, hence supplying some clues about dynamics of continental extension. First-order basement-rooted transverse faults zones are identified and their influence on nucleation and propagation of strain is demonstrated, whereas the role of magmatic ‘soft-spots’ as concentrating strain is minimized. Blocking of deformation as well as rift jump and lateral transfer of strain are discussed in relation to various types of fault interaction (dip direction, strikes and acute/obtuse angle of the intersecting faults). The causal links between rift nucleation ‘cells’ and inherited transverse weakness zones in the Turkana rift might also exist elsewhere along the eastern branch of the East African Rift, hence suggesting a complex and discontinuous mode of rift propagation.

Geology of the “Turkana Grits” in the Lariu range and Mt. Porr areas, southern Lake Turkana, Northwestern Kenya

The onset of tectonism in the northern Kenya Rift is believed to be recorded by the deposition of immature, arkosic sandstones generally referred to as Turkana Grits. These sandstones have been interpreted by various workers as either Cretaceous or Miocene in age. Detailed re-mapping of the Turkana Grits in the Mount Porr (Kajong) area and a new mapping in the Lariu Range, both on the shores of Lake Turkana, coupled with interpretation of newly acquired seismic reflection profiles, have resulted in an integrated interpretation of the age and deposition of the Turkana Grits in these remote areas. In both areas the grits are predominantly coarse-grained, basement derrived sandstones deposited on a dissected basement topography by aggrading fluvial systems. Locally, syndepositional faulting has displaced and rotated some of the sandstones. Although the sediments are unfossiliferous in both areas, from their relationships with the basement and overlying volcanics, and their place within the regional tectonic context, it appears that the Turkana Grits in the southern Lake Turkana area are probably Oligo-Miocene deposits.

Tectonic evolution of the northern Kenyan Rift

Recent geological fieldwork, radiometric age dating of volcanic rocks, gravity and seismic reflection surveys have considerably refined our understanding of the tectonic evolution of the northern Kenya Rift. These data reveal that deep, half-graben basins up to 7 km thick were initiated west of Lake Turkana probably during Late Oligocene-Early Miocene times. The basins, bounded by easterly dipping faults, trend along the western side of the rift from Lake Turkana to the Elgayo Escarpment-Tugen Hills area. Some rift basins were episodically active from the Oligocene to the Pliocene while others were only active for a few million years. Some sag basins may have developed during periods of rifting quiescence. In the Turkana area the location of faulting gradually shifted eastwards with time. Volcanism both preceded and accompanied rifting. Within the Turkana area, volcanism moved south and east with time, beginning about 33 Ma (probably preceding half graben formation by a few million years) and continued to the present day. Extension along faults is greater in the Turkana area (between 25-40 km) and decreases southwards to probably 5-10 km or less in the southern Kenya rift. This pattern of extension values agrees with deep seismic refraction work (KRISP), which indicates thin crust in the Turkana area (about 20 km) that thickens to about 35 km south of Lake Baringo. The extension values, crustal thinning, age of volcanism and the timing of faulting to the south all point towards a southerly propagation of the rift.

1. Epidemiological observations

A brief account is given of the geographical features of the Turkana area and of the events which led to the discovery that this part of Kenya had the highest incidence of clinically recognized hydatid disease in man anywhere in the world. Observations were made on the distribution of the disease following an aerial survey designed to determine the distribution of the people. It was found that the highest incidence of 198 surgical cases per 100,000 people per annum was in the north-western area bordering on the Sudan, Ethiopia and Uganda and this area was selected for the pilot control programme. By the development and assessment of better serodiagnostic methods combined with the use of a mobile ultrasound machine it has been shown that the true prevalence of hydatid disease in Turkana is between 5 and 10%. Studies on the parasite and its transmission have revealed that the species in Turkana is Echinococcus granulosus and that dogs and jackals are the main definitive hosts. Although goats, sheep, cattle and camels are all infected with hydatid cysts, dogs and jackals are also thought to be infected by scavenging on human corpses. In contrast to Masailand where wild carnivores and wild herbivores are infected, there is no wild life cycle in Turkana. The unusually high prevalence in man is thought to be due to the close intimacy of the Turkana with their dogs and to customs relating to the handling of dog faeces. Advances in immuno-differentiation and the use of DNA probes for distinguishing Echinococcus from taeniid eggs are likely to provide new tools for the diagnosis of infection in dogs and jackals and for studying the dispersal of eggs in the environment.

Paleoenvironments of Root Casts from the Koobi Fora Formation, Kenya

A study of fossil mots and root casts from East Turkana, Kenya, has shown them to be useful paleoenvironmental indicators. Fossil root casts were obtained from the Pleistocene, Upper Member of the Koobi Fora Formation, deposited within the East Turkana Embayment of the Lake Turkana Basin. Lithofacies and biofacies analysis of the study locality allows the discrimination of several important environments which contain root casts, notably fluvial channels and shallow lacustrine conditions. Five common root cast morphologies have been observed: 1) horizontal, planar root mats; 2) vertical or vertically branching structures; 3) horizontal or horizontally branching structures; 4) diagonally branching structures; and 5) root balls (concretionary structures). Root cast morphology is shaped both by the original root morphology and post-mortem, diagenetic development. Line transect surveys of fossil root casts reveal two striking lithofacies-root cast associations. Laminated siltstones of the shallow lacustrine environment primarily contain root mats and horizontal roots, whereas sandstone-conglomerates of the fluvial paleochannels contain predominantly vertical and diagonal root casts, with no root mats. Studies of plant associations in the Lake Turkana area, and work on modern root morphologies suggest a probable explanation for these associations. In arid environments, water availability is a dominant factor in root morphology. Plants growing along intermittent streams or floodplains must frequently rely on perched water bodies or deeper phreatic water, therefore sending out long, vertical tap roots to take advantage of this resource. Plants living in permanent, shallow lacustrine environments or other areas where phreatic water is quite shallow have no such requirement, since their roots are nearly continuously immersed in ground water; during floods the plant stalk itself is subaqueous. The roots of these plants tend to extend laterally in thin mats over large areas. Thus, a study of root cast morphologies may allow for an assessment of paleogroundwater conditions in nonmarine sediments.

Oligocene transitional tholeiitic magmatism in Northern turkana (Kenya): Comparison with the Coeval Ethiopian volcanism

Near Lokitaung in the northernmost part of the Turkana area, transitional tholeiitic basalts about 30 m.y. old overlie the Turkana grits. Coeval, essentially alkaline «basalts» outcrop in the neighbouring zone of Kalin. These rocks represent the southernmost occurrences of the great and extended volcanism which took place in Ethiopia and in part of the Arabian peninsula in Oligocene times. The ascription of the Oligocene Turkana basalts to the Ethiopian volcanic activity is supported by structural, volcanological, geochemical and mineralogical analogies with coeval lavas from N and S Ethiopia. In this respect, clinopyroxene composition resulted to be especially meaningful. In the course of the Oligocene volcanic activity, basic magmas changed their composition at a rate which varied from zone to zone. This rate is considered to be depended on whether the considered zones occupy a more or less peripheral position with respect to the Ethiopian dome.

Ethnobotany of the Turkana: Use of plants by a pastoral people and their livestock in Kenya

Evidence from the south Turkana area of Kenya throws light on the manner and extent to which a nomadic pastoral people make use of the plant species in their environment. The Royal Geographical Society South Turkana Expedition spent 3 field seasons during 1968-70 collecting over an area of 9,500 km2 to the south and west of Lake Turkana (Fig. 1). Altitudes range from 251-1,375 m (Caukwell, 1971; Baker and Lovenbury, 1971). Ground conditions are variable, including crystalline metamorphics, lavas, sandstones and sands derived from these, and there are alkaline springs. Rainfall is believed to average less than 250 mm/yr with a rainy season normally during March-May, but highly variable in both quantity and periodicity (Gwynne, 1969; Morgan, 1971). A reconnaissance classification of the ecology of the area is provided by Hemming (1972) and a detailed account of a sample area by Morgan (1971). The dominant vegetation type is semidesert thorn scrub with Acacia tortilis (Forsk.) Hayne and A. reficiens Wawra and Peyr. ssp. misera (Vatke) Brenan prominent above small browse plants, commonly including Indigofera spinosa Forsk. and Sericocomopsis hildebrandtii Schinz. A belt of riverine forest along the Kerio river is dominated by well-developed Acacia tortilis and Cordia sinensis Lam. (synonyms: C. rothii Roem. and Schult. and C. gharaf (Forsk.) Aschers). The 3 collecting seasons may be characterized as dry; very dry; and receding rainy season; and it is believed that the 1,1 11 specimens collected are reasonably representative. From this collection, 512 species or subspecies were identified, consisting of 366 Dicotyledons and 101 Monocotyledons, including 65 Gramineae. The use made of the plants and their vernacular names were recorded at the time of collection, and a large proportion were further discussed by groups of informants at base camp. The results are presented in the Appendix. Gulliver (1950, 1955) referred briefly to the use made of plants in his study of Turkana society. Notes on Masai and Kipsigis use of plants were published following an ecological survey of the comparably pastoral but less arid Narok District of Kanya Masailand (Glover et al., 1966). Medicinal uses of plants in east Africa are summarised in Kokwaro (1976) and Watt and Breyer-Brandwijk (1962).

The South Turkana Expedition: Scientific Papers III. A Geological Reconnaissance of South Turkana

South Turkana as referred to in this paper is the area currently being investigated by the Royal Geog aphical Society Sout Turkana Expedition. The area (Fig. i) covers some 9500 km2 immediately to the south of Lake Rudolf in Northern Kenya. It embraces the southern and south-western shores of Lake Rudolf together with those parts of the northward flowing Kerio and Suguta rivers and the intervening high ground ofthe Loriu Plateau which are north of i?3o'N. A more detailed description of the region with precise boundaries is given by Gwynne (1969). During the first field season (July-August 1968) the author undertook a geological reconnaissance of the area in order to prepare a geological map and report for subse? quent use by the South Turkana Expedition. This paper embodies the findings of that report. The earliest geological work in the area was carried out in 1888 in the course of an expedition to* Lake Rudolf under the leadership of Count Paul Teleki. Various aspects of the geology were described by Hohnel (1891), Rosiwal (1891), Toula (1891) and Suess (1891). An active volcano at the southern end of Lake Rudolf was named after Teleki. Angelis d'Ossat and Millosevich (1900) described the material collected by Sacchi before his untimely death during Bottego's expedition to the Lake Rudolf area in 1895-7. In a report on the northern parts of the then East African Protectorate, Parkinson (1920) made only passing reference to the present area. Gregory (1921) devoted a chapter to the northern section of the rift valley in Kenya, though he himself had not visited the region described here. The Cambridge Expedition of 1930-1 (Fuchs, 1934) was concerned primarily with the parts of the area bordering Lake Rudolf. Two years later, Arambourg (1934a; 1934b; 1935; 1943) carried out reconnaissance traverses south of Lake Rudolf, though the main object ofthe expedition was a study ofthe fossiliferous deposits ofthe Omo region at the northern end of the lake. Murray-Hughes (1933) summarized the geology of the western half of Kenya. He named flat-lying sediments which rest on the Basement Complex west of Lake Rudolf the Turkana Grits, tentatively refer ring them to the Jurassic. The greater part of the South Turkana area was shown as being covered by undifferentiated volcanics. Murray-Hughes evidently relied entirely on the work of Champion, an administrative officer, for data on the Turkana region. Champion (1935a; 1935b; 1937a; 1937b) subsequently published several accounts of the volcanic geology and physiography of the country south and west of Lake Rudolf; the volcanic rocks he collected were described by Smith (1938). Fuchs (1939) led an earlier Royal Geographical Society expedition to the region around Lake Rudolf in 1934. Inadequate knowledge ofthe surrounding areas, in particular the ground to the south, hampered the full interpretation of geological events in the Lake Rudolf basin. Dodson (1963) described the geology of that part of the South Turkana area

Moringa: A Correction

This note is the result of the investigation of an erroneous determination published recently by Mr. Dale and myself. In 'Indigenous Trees of Uganda' Second Edition, p. 265 (1952) a description of a Moringa, said to be from Karamoja, Uganda (but very probably from just within the Kenya border), is given under the name M. peregrina (Forsk.) Fiori and a specimen Eggeling 5615 cited. When a specimen of a Moringa, also from the Turkana area of Kenya, was collected by Mr. C. F. Hemming (Hemnrng 275), I immediately identified it with the Eggeling sheet and published the record (Kew Bull. 1955, 6o01 (1956) ) under the same name, without realising that M. peregrin2 is conspecific with M. aptera Gaertn. This error is really quite absurd and unforgivable, since M. peregrina has small leaflets and almost wingless fruits, whereas the Turkana species has large, pointed leaflets and seeds with wings at least 6 cm. long! M. peregrina does not occur in Kenya and Uganda at all but has a northeasterly distribution. At least four species of Moringa occur in East Africa and the naming of Henining 275 involved the borrowing of the types of various species described by E. Chiovenda and A. Engler. I am indebted to Prof. Pichi-Sermolli for the loan of these types. It was at once apparent that the Turkana species is conspecific with Moringa streptocarpa Chiov. The thickened apiculae of the pubescent leaves, the large seed wings and the grooved capsule valves are identical. The Turkana specimen has, however, much shorter capsules. The type material of M. streptocarpa partly consists of an immature capsule 44 cm. long and almost topotypic material from Moyale in Kenya, kindly collected by Mr. D. W. R. Evans at my request, shows that mature capsules are 50 cm. long and 2-5 cm. wide, with seeds 8-8-5 cm. long, including the wings. The Turkana specimen on the other hand, has the capsules only 19'75 cm. long and 2-3-2-6 cm. broad but otherwise identical in shape and texture. The seeds, also, are almost identical in shape and size. It is possible that further material will demonstrate that the short-capsuled Turkana form is a distinct nameable variant but insufficient material is available.