Landslide Hazard Zonation Using Expert Evaluation Technique: A Case Study of the Area Between Gohatsion Town and The Abay (Blue Nile) River, Central Ethiopia

The area between Gohatsion town and the Abay River in Central Ethiopia is witnessing severe problems of landslides during rainy seasons. These landslides in the area affect the safe functioning of the road, which is an essential link between Addis Ababa and the northwestern part of the country. In the present study, an attempt is made to delineate the area into landslide hazard zones (lhz). The landslide hazard zonation was carried out by “Landslide Hazard Evaluation Factor” (lhef) rating scheme. The lhef is an expert evaluation technique that is based on the observational past experience gained over causative factors and their contribution for instability of slopes in the area. The causative factors responsible for landslide activity, which were considered during the present study, are: relative relief, slope morphometry, geology, groundwater and land use/ land cover. The information pertaining to these causative factors was collected from the field and analyzed as per the lhef scheme. The evaluated lhz revealed that most of the study area falls within the moderate and high hazard zones. The existing road that links Addis Ababa with the northwestern part of the country mostly passes through high hazard zones and some of it passes through moderate hazard zones. This seems to be the main reason for frequent landslides along the road during the rainy season. Thus, it is imperative to conduct detailed investigations to suggest proper remedial measures for slope stabilization along the road section or to realign the road section to avoid such critical slope sections

Pleistocene sea-floor fibrous crusts and spherulites in the Danakil Depression (Afar, Ethiopia)

Pleistocene fibrous aragonite fabrics, including crusts and spherules, occur in the Danakil Depression (Afar, Ethiopia) following the deposition of two distinctive Middle and Late Pleistocene coralgal reef units and pre‐dating the precipitation of evaporites. Crusts on top of the oldest reef unit (Marine Isotope Stage 7) cover and fill cavities within a red algal framework. The younger aragonite crusts directly cover coralgal bioherms (Marine Isotope Stage 5) and associated deposits. Their stratigraphic position between marine and evaporitic deposits, and their association to euryhaline molluscs, suggest that the crusts and spherules formed in restricted semi‐enclosed conditions. The availability of hard substrate controls crust formation with crusts more often found on steep palaeo‐slopes, from sea level up to at least 80 m depth, while spherules mainly occur associated with mobile substrate. Crusts reach up to 30 cm in thickness and can be microdigitate, columnar (branching and non‐branching) or non‐ columnar, with laminated and non‐laminated fabrics. Two different lamination types are found within the crystalline fabrics: (i) isopachous lamination; and (ii) irregular lamination. These two types of lamination can be distinguished by the organization of the aragonite fibres, as well as the lateral continuity of the laminae. Scanning electron microscopy with energy dispersive X‐ray spectroscopy analyses on well‐preserved samples revealed the presence of Mg‐silicate laminae intercalated with fibrous aragonite, as well as Mg‐silicate aggregates closely associated with the fibrous aragonite crusts and spherules. The variety of observed fabrics results from a continuum of abiotic and microbial processes and, thus, reflects the tight interaction between microbially mediated and abiotic mineralization mechanisms. These are the youngest known isopachously laminated, digitate and columnar branching fibrous crusts associated with a transition from marine to evaporitic conditions. Understanding the context of formation of these deposits in Afar can help to better interpret the depositional environment of the widespread Precambrian sea‐floor precipitates

Pleistocene aragonite crust diagenesis mimics microbialite fabrics (Danakil Depression, Ethiopia)

Fibrous aragonite crusts occur in two consecutive Pleistocene successions in the Danakil Depression (Afar, Ethiopia). Lateral transitions between pristine and altered fibrous aragonite crusts document changes in texture associated with diagenesis. Crusts formed as essentially abiotic seafloor precipitates at the transition from marine to evaporitic conditions. Diagenesis started with the dissolution of aragonite fans at the interface between single fans in non-laminated crusts and along lamination planes in isopachous, irregular, or crudely laminated crusts. Incomplete dissolution resulted in the development of secondary porosity within a matrix of undissolved aragonite fibers. Subsequently, the porosity was filled with calcite that systematically encased remaining aragonite crystals. This was followed by the dissolution of remnant aragonite fibers, producing a network of elongated inter- and intracrystalline pores that were eventually filled with low-Mg calcite. The stepwise substitution of fibrous aragonite by low-Mg calcite resulted in sparry, sparry-cloudy, sparry-micritic (including clotted micrite), and peloidal textures, which obscure the fibrous nature of the original deposits. Stable C- and O-isotope compositions suggest that early diagenesis was driven by meteoric and evaporative fluids. These observations unequivocally demonstrate destructive diagenesis, resulting in secondary textures, which mimic micritic and grumous (peloidal and clotted) textures associated with sparry microfabrics. This suggests that these textures, classically interpreted as primary microbial precipitates and used as evidence of biogenicity in ancient microbialites, might be diagenetic products in some cases, even though at some stage, microbial processes and/or degradation of organic matter could have been involved in the diagenetic process

Earliest stone-tipped projectiles from the Ethiopian Rift date to> 279,000 years ago

Projectile weapons (i.e. those delivered from a distance) enhanced prehistoric hunting efficiency by enabling higher impact delivery and hunting of a broader range of animals while reducing confrontations with dangerous prey species. Projectiles therefore provided a significant advantage over thrusting spears. Composite projectile technologies are considered indicative of complex behavior and pivotal to the successful spread of Homo sapiens . Direct evidence for such projectiles is thus far unknown from >80,000 years ago. Data from velocity-dependent microfracture features, diagnostic damage patterns, and artifact shape reported here indicate that pointed stone artifacts from Ethiopia were used as projectile weapons (in the form of hafted javelin tips) as early as >279,000 years ago. In combination with the existing archaeological, fossil and genetic evidence, these data isolate eastern Africa as a source of modern cultures and biology

Petroleum source rock characteristics of the Mesozoic units, Mekelle Basin, northern Ethiopia

The Mekelle Basin comprises carbonate and siliciclastic rocks which could have potential for petroleum as previous studies reported without enough evidence. This research is intended to assess source rock characteristics of selected samples from the Adigrat Sandstone, Antalo Limestone and Agula Shale. Four outcrop sections were investigated and fifteen limestone and shale samples were collected. TOC was deduced by Leco SC-632 carbon analyzer, and Rock-Eval pyrolysis was determined using Rock-Eval 6. The TOC values range from 0.11 wt.% to 0.42 wt % for 80% of the samples which is less than the minimum requirements for source rocks. However, a few samples have TOC between 0.5 wt % and 1.0 wt %, indicating fair organic matter richness. The kerogen is mainly Type IV and inert. The S1 (0–0.02 mgHC/g) and S2 (0–0.07 mgHC/g) values are very low, with very high Tmax (475–527 °C), indicating very poor potential with over-mature dry gas. Therefore, the analyzed samples have low organic content for hydrocarbon, implying that the studied units have no feasible source rock potential

Sexuality, agency and intertextuality in the later poetry of John Clare

SIGLEAvailable from British Library Document Supply Centre-DSC:DXN028358 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Bathymetric and structural data of Lake Afdera and surroundings, Afar, Ethiopia

We present data from the Lake Afdera (13.26N; 40.90E) and its surrounding. Equipped with a small inflatable boat and an echosounder (Humminbird, 899ci hd si system), we surveyed the lake to obtain its first complete bathymetric map. We further investigated the fault pattern around the lake to interpret the lineaments observed in the bathymetry

Box-and-Whisker plots of TCSA and TCSP comparisons.

<p>TCSA and TCSP plots of pointed pieces from experimental spear tips <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0078092#pone.0078092-Shea3" target="_blank">[25]</a> (Exprm); Klasies River main site MSA I <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0078092#pone.0078092-Wurz1" target="_blank">[32]</a> (KRM); Gademotta (GDM). Solid dots represent outlier values.</p