Corrigendum: Geochronology of the Turkana Depression of Northern Kenya and Southern Ethiopia

The region of Southern Ethiopia (Borana) and Northern Kenya (Marsabit) is characterised by erratic rainfall, limited surface water, aridity, and frequent droughts. An important adaptive response to these conditions, of uncertain antiquity, has been the hand-excavation of a sequence of deep wells at key locations often along seasonal riverbeds and valley bottoms where subterranean aquifers can be tapped. Sophisticated indigenous water management systems have developed to ensure equitable access to these critical water resources, and these are part of well-defined customary institutional leadership structures that govern the community giving rise to a distinctive form of biocultural heritage. These systems, and the wells themselves, are increasingly under threat, however, from climate change, demographic growth, and socio-economic development. To contribute to an assessment of the scale, distribution and intensity of these threats, this study aimed to evaluate the land-use land-cover (LULC) and precipitation changes in this semi-arid to arid landscape and their association with, and impact on, the preservation of traditional wells. Multitemporal Landsat 5, 7 and 8 satellite imagery covering the period 1990 to 2020, analysed at a temporal resolution of 10 years, was classified using supervised classification via the Random Forest machine learning method to extract the following classes: bare land, grassland, shrub land, open forest, closed forest, croplands, settlement and waterbodies. Change detection was then applied to identify and quantify changes through time and landscape degradation indices were generated using the Shannon Diversity Index fragmentation index within a 15 km buffer of each well cluster. The results indicated that land cover change was mostly driven by increasing anthropogenic changes with resultant reduction in natural land cover classes. Furthermore, increased fragmentation has occurred within most of the selected buffer distances of the well clusters. The main drivers of change that have directly or indirectly impacted land degradation and the preservation of indigenous water management systems were identified through an analysis of land cover changes in the last 30 years, supporting insights from previous focused group discussions with communities in Kenya and Ethiopia. Our approach showed that remote sensing methods can be used for the spatially explicit mapping of landscape structure around the wells, and ultimately towards assessment of the preservation status of the indigenous wells.

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Orbital Influence on Precipitation, Fire, and Grass Community Composition From 1.87 to 1.38 Ma in the Turkana Basin, Kenya

Frontiers in Earth Science ◽

10.3389/feart.2021.568646 ◽

2021 ◽

Vol 9 ◽

Author(s):

Chad L. Yost ◽

Rachel L. Lupien ◽

Catherine Beck ◽

Craig S. Feibel ◽

Steven R. Archer ◽

...

Keyword(s):

Environmental Change ◽

Community Composition ◽

High Amplitude ◽

Homo Erectus ◽

Southern Ethiopia ◽

Time Interval ◽

Northern Kenya ◽

Turkana Basin ◽

Core Study ◽

Vegetation Surveys

The Turkana Basin in northern Kenya and southern Ethiopia has yielded hundreds of hominin fossils and is among the most important localities in the world for studying human origins. High resolution climate and vegetation reconstructions from this region can elucidate potential linkages between hominin evolution and environmental change. Microcharcoal and phytoliths were examined from a 216 m (1.87–1.38 Ma) drill core (WTK13), which targeted paleo-Lake Lorenyang sediments from the Nachukui Formation of the Turkana Basin. A total of 287 samples were analyzed at ∼32–96 cm intervals, providing millennial-scale temporal resolution. To better understand how basin sediments record fire and vegetation from the watershed, the paleorecord was compared with nine modern sediment samples collected from Lake Turkana along a transect of increasing distance from the 1978 to 1979 shoreline. This included vegetation surveys and phytolith production data for species from areas proximal to the basin. We found that phytolith and microcharcoal concentrations decreased predictably moving off shore. However, phytoliths from plants sourced in the Ethiopian Highlands increased moving off shore, likely the result of increased exposure to the Omo River sediment plume. In our down-core study, microcharcoal was well-preserved but phytolith preservation was poor below ∼60 m (∼1.50 Ma). Spectral analysis revealed that microcharcoal often varied at precessional (∼21 kyr) periodicities, and through a correlation with δDwax, linked orbitally forced peaks in precipitation with elevated fire on the landscape. Phytoliths revealed that alternating mesic C4 versus xeric C4 grass dominance likely varied at precessional periodicities as well, but that grass community composition was also mediated by basin geometry. Two high eccentricity intervals of particularly high amplitude and abrupt environmental change were centered at ∼1.72 and 1.50 Ma, with the intervening period experiencing high fire variability. With the switch from lacustrine to fluvial-deltaic deposition at the core site by 1.5 Ma, mesic C4 grasses dominated and fire activity was high. This upper interval correlated to the time interval from which Nariokotome Boy (Homo erectus/ergaster) was discovered 3 km east of our drill site. Phytoliths indicated a seasonally wet and open landscape dominated by xeric C4 grasses, sedges, and other herbaceous plants.

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The Origins of the Galla and somali

The Journal of African History ◽

10.1017/s0021853700006058 ◽

1966 ◽

Vol 7 (1) ◽

pp. 27-46 ◽

Cited By ~ 32

Author(s):

Herbert S. Lewis

Keyword(s):

Sixteenth Century ◽

Tenth Century ◽

Previous Literature ◽

Traditional View ◽

Southern Ethiopia ◽

Gulf Of Aden ◽

Horn Of Africa ◽

Northern Kenya ◽

South West ◽

The Subject

This study presents a reconstruction of the origins and major movements of the Galla and Somali of Northeast Africa which departs from most of the previous literature on the subject. The traditional view has been that the Galla occupied most of the Horn of Africa until the Somali, beginning about the tenth century, swept south and south-west from the shores of the Gulf of Aden driving the Galla before them. The pressure of the Somali has also been considered the major impetus to the Galla invasions of Ethiopia in the sixteenth century. It is the thesis of this paper that both the Galla and the Somali originated in southern Ethiopia, that the Somali expanded to the east and north much earlier than the Galla, and that the Galla lived only in southern Ethiopia and northern Kenya until their migrations began about 1530.

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