Northeastern South Africa Research Articles

<p><strong><em>Aloe</em></strong><strong> ×<em>retiefii</em> (Asphodelaceae subfam. Alooideae), a new nothospecies from northeastern South Africa, with <em>A. globuligemma</em> and <em>A. marlothii</em> as parents</strong></p>

Aloe marlothii Berger (1905: 87) (Asphodelaceae subfam. Alooideae) (Fig. 1), a single-stemmed, tree-like aloe, occurs widespread in northeastern South Africa and adjacent parts of Botswana, for example near Lobatse in the southeast of the country from where it was originally described (Fig. 2), Zimbabwe, and Mozambique (see maps in Klopper & Smith 2010: 92, Fig. 32 and Van Wyk & Smith 2014: 68). Wherever A. marlothii co-occurs with other species of Aloe Linnaeus (1753: 319), hybrids are produced (Reynolds 1950, Smith & Figueiredo 2015). Aloe globuligemma Pole-Evans (1915: 30, Plates X [Figs 1 and 2] and XI [Figs 1, 2, and 3]) (Fig. 3), a stemless, medium-sized aloe, is restricted to the more subtropical parts of northeastern South Africa, southern Zimbabwe, and Mozambique (see map in Van Wyk & Smith 2014: 158). Where these two species, A. globuligemma and A. marlothii, co-occur, for example at Lebowakgomo, about 50 km southeast of Polokwane, the capital of South Africa’s Limpopo province, a bewildering range of striking hybrids with considerable horticultural potential are found (Reynolds 1950: 446, 484, Retief 2018). This hybrid also occurs a bit further south of the Lebowakgomo location, as well as elsewhere in the Limpopo province, in Sekhukhuneland in the vicinity of Steelpoort and Ohrigstad.

Pensions, consumption and health: evidence from rural South Africa

BackgroundIncreasing numbers of older people in sub-Saharan Africa are gaining access to pension benefits and it is often claimed that these benefits promote healthy forms of consumption, which contribute to significant improvements in their health status. However, evidence to support these claims is limited.MethodsThe paper uses data for 2701 people aged 60 or over who participated in a population-based study in rural north-eastern South Africa. It analyses effects of receiving a pension on reported food scarcity, body mass index and patterns of consumption.ResultsThe paper finds that living in a pension household is associated with a reduced risk of reported food scarcity and with higher levels of consumption of food and drink. The paper does not find that living in a pension household is associated with a higher prevalence of current smoking nor current alcohol consumption. However, the paper still finds that tobacco and alcohol make up over 40% of reported food and drink consumption, and that the correlation between reported food scarcity and body mass index status is imperfect.ConclusionsThe paper does not show significant associations between pension receipt and the selected risk factors. However, the context of prevalent obesity and high shares of household spending allocated to tobacco and alcohol call into question widely-made claims that pensions enhance healthy consumption among older people in low and middle-income countries.

Response of Soil pH and Nodulation of Three Chickpea Genotypes to Biochar and Rhizobium Inoculation

ABSTRACT Soils in the semi-arid regions such as north-eastern South Africa, where chickpea was recently introduced, are commonly characterized by poor fertility and low pH. Preliminary studies show that the crop has a huge potential in the region, but lack of nodulation has consistently been a problem. We assessed the response of soil pH and nodulation of three chickpea genotypes (ACC #4, ACC #5, and ACC #6) to biochar application (0, 10, and 20 t ha−1) and rhizobium inoculation (inoculated and uninoculated) in Thohoyandou (clay soil) and Nelspruit (loamy sand soil), South Africa in 2015 and 2016. Nodulation was assessed at flowering by determining the number of nodules per plant and nodule dry weight, and soil pH was analyzed after harvest in both seasons. Biochar increased pH by 0.7 (clay soils) and 0.7–0.8 (the more acidic loamy sand soils) pH units. Similarly, biochar increased nodulation in inoculated treatments in both locations and seasons, and this was mainly associated with the effect of biochar on soil pH. The increase in nodulation with inoculation varied amongst the genotypes. Clearly biochar and rhizobium inoculation may be crucial for improving soil pH and nodulation in chickpea cropping systems characterized by poor soils.

A late Mesozoic – early Cenozoic sedimentary recycling system on the Gondwana rifted margin of southeast Africa

Abstract Detrital zircons in late Cretaceous – Palaeogene, calcareous sandstone and conglomerate deposited in continental basins on the southeastern African margin after the breakup of Gondwana have characteristic combinations of age and epsilon-Hf that indicate an origin by recycling of Palaeoproterozoic (Waterberg, Soutpansberg and Pretoria groups) and Phanerozoic (Karoo Supergroup) cover successions. The latter is dominant in the south and east (Boane, Mahosi, Chilojo Cliffs), and the Palaeoproterozoic sources in the northwest (Pafuri, Wright’s Tower, Masisi). This recycling and mixing regime was restricted to late Mesozoic and Palaeogene time in northeastern South Africa and adjoining parts of Mozambique and Zimbabwe. Detrital zircon distribution patterns in these deposits reflect the denudation history of the southern African continental surface after breakup of the Gondwana supercontinent.

Temperature explains variation in seasonal temporal activity of Miniopterus natalensis more than moonlight or humidity

Animals partition their daily activities based on a variety of internal and external factors. For insectivorous bats, the availability of prey, weather conditions, moonlight and reproductive energy demands are proposed as the major influencers of temporal activity. This study investigated the temporal variation in activity of the subtropical cave-dwelling, migratory Natal long-fingered bat, Miniopterus natalensis, by temperature, humidity, lunar illumination and the time of moonrise per night. Using echolocation survey data collected 2014–2018 near a maternity roost in north-eastern South Africa, differences in activity between the summer maternity (1 September–28 February) and winter non-breeding (1 March–31 August) seasons were described. In the non-breeding season, M. natalensis exhibited peak activity during the early evening, with decreasing activity throughout the night. In the maternity season, a bimodal activity pattern was observed, probably related to peaks in insect activity and the energy requirements of lactating females. Predictably, temperature had the strongest positive influence on the magnitude of M. natalensis activity across both seasons. Humidity also positively affected activity in both seasons to a lesser extent. The time of moonrise did not affect the activity of M. natalensis during either of the seasons. Lunar illumination did not affect activity during the maternity season, but activity was diminished on nights with bright moonlight in the non-breeding season. Emergence and return times were not affected by lunar illumination in either season. The need of M. natalensis to maximise resource acquisition during the maternity season is likely a strong modulator in the temporal activity of this species and outweighs predation risk in high moonlight conditions. Subsequently, this species exhibits nightly activity behaviours that balance risk factors with intrinsic needs during different seasons.

Identification of solar periodicities in southern African baobab δ13C record

Spectral analysis using wavelet, Lomb–Scargle and maximum entropy techniques of the proxy rainfall record of northeastern South Africa based on annual carbon isotope (δ13C) data obtained from baobab trees for the period 1600 AD – 2000 AD show clear evidence of the presence of characteristic solar periodicities. Solar periodicities that were identified above the 95% confidence level include the ~11-year Schwabe cycle, the ~22-year Hale cycle as well as the 80–110-year Gleissberg cycle. A Morlet wavelet analysis of the δ13C data between 1600 AD and 1700 AD shows the effect of the Maunder sunspot minimum on both the Schwabe and Hale cycles during this time.
 Significance:
 
 A spectral analysis of δ13C baobab tree ring data for southern Africa between 1600 AD and 2000 AD is presented. The results show – for the first time – that the δ13C time series contains the 11-year Schwabe, 22-year Hale as well as the 80–110-year Gleissberg solar periodicities. In addition, the influence of the Maunder sunspot minimum between ~1650 AD and 1715 AD could also be clearly identified in the δ13C data for the first time. These findings are of significant importance to investigations of solar influences on climate variability.

Traditional healers use of personal protective equipment: a qualitative study in rural South Africa

BackgroundTraditional healers are frequently exposed to hepatitis B virus (HBV), hepatitis C virus (HCV), and human immunodeficiency virus (HIV) through the widespread practice of traditional “injections”, in which the healer performs dozens of subcutaneous incisions using a razor blade to rub herbs directly into bloodied tissue. An average healer in Agincourt, a rural northeastern sub-district in Mpumalanga province, South Africa, experiences approximately 1500 occupational blood exposures over the course of their lifetime. Healers in Agincourt have an HIV prevalence of 30% compared to 19% in the general population, and healers who report exposure to patient blood have an adjusted 2.4-fold higher odds of being HIV-positive than those with no exposure. Although research on appropriate PPE use has been well documented for allopathic care providers, little is known about the practices of traditional healers.MethodsThis qualitative study was conducted with 30 traditional healers who practice in the rural Bushbuckridge sub-district of Mpumalanga province, northeastern South Africa. We elicited traditional healer attitudes towards glove use during traditional treatments – including patient baths, injections, or other treatments that exposed healers to patient blood or open sores.ResultsWhile 90% of healers reported using latex gloves during some treatments, the majority do not use them regularly. Most employ a combination of gloves, plastic shopping bags, bread bags, paper, and sticks to prevent blood exposure. Healers reported plastic bags slipping or breaking during procedures, exposing them to patient blood. Only three healers consistently used gloves, regardless of the cost.ConclusionsInadequate PPE use and high HIV prevalence make traditional healers particularly susceptible to contracting HIV in rural South Africa. Despite positive attitudes, consistent glove use remains low due to financial constraints and glove availability. Addressing issues of accessibility and cost of gloves for traditional healers could have a significant impact on the adherence to PPE and, in turn, reduce new HIV infections among this high-risk group.

Epilepsy care cascade, treatment gap and its determinants in rural South Africa

PurposeThe percentage of people who are diagnosed with epilepsy (diagnostic gap), access, receive and adhere (treatment gap) to anti-seizure medication (ASM) in low- and middle- income countries remains low. We explored the epilepsy care cascade, measured the diagnostic and treatment gaps, and examined socio-demographic factors associated with adherence to ASMs in rural South Africa. MethodsUtilizing a population-based cohort of 311 people with active convulsive epilepsy (ACE) residing in rural northeastern South Africa, a questionnaire was administered to examine associations between demographic and socioeconomic factors and the epilepsy treatment gap. Blood was taken to measure levels of ASMs. ResultsOf the 311 individuals diagnosed, 93 % of individuals reported being previously told they had epilepsy and 94 % reported previously attending a health facility for their epilepsy. ASMs were detected in 138 individuals (76 %) and optimal levels were detected in 67 individuals, resulting in a treatment gap of 63 % (95 % confidence interval [95 %CI]: 56 %–70 %). Self-reported specificity of ASM use was 23 % (95 %CI: 12–39 %) and individuals ≥18 years were significantly more likely to report taking ASM than children and were significantly (p = 0.011) more likely to be adherent. ConclusionMost people with epilepsy in rural South Africa had been previously diagnosed with epilepsy and had accessed care for epilepsy, yet the level of ASM adherence remained low, significantly lower amongst children. Understanding ways of improving knowledge of and adherence to ASM in rural South Africa is necessary, especially amongst children. The epilepsy care cascade can be useful in identifying gaps in care and targeting interventions to reduce these gaps.

Statistical analysis of factors driving surface ozone variability over continental South Africa

ABSTRACT Statistical relationships between surface ozone (O3) concentration, precursor species and meteorological conditions in continental South Africa were examined from data obtained from measurement stations in north-eastern South Africa. Three multivariate statistical methods were applied in the investigation, i.e. multiple linear regression (MLR), principal component analysis (PCA) and –regression (PCR), and generalised additive model (GAM) analysis. The daily maximum 8-h moving average O3 concentrations were considered in these statistical models (dependent variable). MLR models indicated that meteorology and precursor species concentrations are able to explain ~50% of the variability in daily maximum O3 levels. MLR analysis revealed that atmospheric carbon monoxide (CO), temperature and relative humidity were the strongest factors affecting the daily O3 variability. In summer, daily O3 variances were mostly associated with relative humidity, while winter O3 levels were mostly linked to temperature and CO. PCA indicated that CO, temperature and relative humidity were not strongly collinear. GAM also identified CO, temperature and relative humidity as the strongest factors affecting the daily variation of O3. Partial residual plots found that temperature, radiation and nitrogen oxides most likely have a non-linear relationship with O3,while the relationship with relative humidity and CO is probably linear. An inter-comparison between O3 levels modelled with the three statistical models compared to measured O3 concentrations showed that the GAM model offered a slight improvement over the MLR model. These findings emphasise the critical role of regional-scale O3 precursors coupled with meteorological conditions in daily variances of O3 levels in continental South Africa.

Short-Term and Medium-Term Drought Forecasting Using Generalized Additive Models

Forecasting extreme hydrological events is critical for drought risk and efficient water resource management in semi-arid environments that are prone to natural hazards. This study aimed at forecasting drought conditions in a semi-arid region in north-eastern South Africa. The Standardized Precipitation Evaporation Index (SPEI) was used as a drought-quantifying parameter. Data for SPEI formulation for eight weather stations were obtained from South Africa Weather Services. Forecasting of the SPEI was achieved by using Generalized Additive Models (GAMs) at 1, 6, and 12 month timescales. Time series decomposition was done to reduce time series complexities, and variable selection was done using Lasso. Mild drought conditions were found to be more prevalent in the study area compared to other drought categories. Four models were developed to forecast drought in the Luvuvhu River Catchment (i.e., GAM, Ensemble Empirical Mode Decomposition (EEMD)-GAM, EEMD-Autoregressive Integrated Moving Average (ARIMA)-GAM, and Forecast Quantile Regression Averaging (fQRA)). At the first two timescales, fQRA forecasted the test data better than the other models, while GAMs were best at the 12 month timescale. Root Mean Square Error values of 0.0599, 0.2609, and 0.1809 were shown by fQRA and GAM at the 1, 6, and 12 month timescales, respectively. The study findings demonstrated the strength of GAMs in short- and medium-term drought forecasting.

Uncovering the Late Pleistocene LSA of Mpumalanga Province, South Africa: Early Results from Iron Pig Rock Shelter

Abstract South Africa is one of the best-studied regions in terms of Stone Age research in the last few decades. Considerable progress has been made, especially for the Middle Stone Age (MSA). Recently the late Pleistocene Later Stone Age (LSA) has come back into focus. However, there are still large understudied areas such as northeastern South Africa. Here we present the first data from an archaeological site containing late Pleistocene occupations associated with the Robberg techno-complex in this region. Iron Pig rock shelter provides a well-dated sequence spanning from >16000 cal BP to <9000 cal BP. A lithic analysis of the Robberg occupations of the lowermost layers 5 and 6 provided here implies gradual temporal shifts in technology indicating short-term changing traditions. A comparative review of other LSA sites in the wider region suggests considerable research gaps and the necessity of intensified work in this area.

Challenges with tracing patients on antiretroviral therapy who are late for clinic appointments in rural South Africa and recommendations for future practice

ABSTRACT Background: It is common practice for HIV programmes to routinely trace patients who are late for a scheduled clinic visit to ensure continued care engagement. In South Africa, patients who are late for a scheduled visit are identified from clinic registers, and called by telephone up to three times by designated clinic staff, with home visits conducted for those who are unreachable by phone. It is important to understand outcomes among late patients in order to have accurate mortality data, identify defaulters to attempt to re-engage them into care, and have accurate estimates of patients still in care for planning purposes. Objective: We conducted a study to assess whether tracing of HIV patients in clinics in rural north-eastern South Africa was implemented in line with national policies. Methods: Thirty-three person-day of observations took place during multiple visits to eight facilities between October 2017 and January 2018 during which clinic tracing processes were captured. The facility level implementation processes were compared to the intended tracing process and gaps and challenges were identified. Results: Challenges to implementing effective tracing procedures fell into three broad categories: i) facility-level barriers, ii) issues relating to data, documentation and record-keeping, and iii) challenges relating to the roles and responsibilities of the different actors in the tracing cascade. We recommend improving linkages between clinics, improving record-keeping systems, and regular training of community health workers involved in tracing activities. Improved links between clinics would reduce the chance of patients being lost between clinics. Record-keeping systems could be improved through motivating health workers to take ownership of their data and training them on the importance of complete data. Finally, training of community health workers may improve sustained motivation, and improve their ability to respond appropriately to their clients’ needs. Conclusions: Substantial investment in data infrastructure and healthcare staff training is needed to improve routine tracing.

Walking towards a camera obscura

The paper is located within the wider field of decolonial practice where those of us who were previously marginalized from ‘mainstream’ knowledge production by colonialism and its structures address the question of how we navigate ways of knowing from our own point of view. The paper places the concept of ‘walking about’ in relation to the Khelobedu saying ‘go sepela ke go bona’, both of which have parallels with the methodologies that Walter Benjamin espoused through the figure of the flâneur. The paper tracks my walkabouts as I follow the travels of several Balobedu from north-eastern South Africa to Berlin in 1897, by travelling to Berlin and other contemporary art centres myself. The practice of travelling offered opportunities in the form of dream as a khelobedu text, introduced me to installation art and led me to experiment with the idea and practice of the camera obscura, allowing me to confront some of the limits of photographic documentation. Overall, the paper argues that ‘walking about’ as a methodology resolves some of the difficulties with ideas of visuality associated with khelobedu and with mediating a text that demands a critical awareness of the relationship between the senses. The camera obscura, as a space that houses a body, becomes this medium and the text.

Misreporting of Patient Outcomes in the South African National HIV Treatment Database: Consequences for Programme Planning, Monitoring, and Evaluation.

Background: Monitoring progress toward global treatment targets using HIV programme data in sub-Saharan Africa has proved challenging. Constraints in routine data collection and reporting can lead to biased estimates of treatment outcomes. In 2010, South Africa introduced an electronic patient monitoring system for HIV patient visits, TIER.Net. We compare treatment status and outcomes recorded in TIER.Net to outcomes ascertained through detailed record review and tracing in order to assess discrepancies and biases in retention and mortality rates.Methods: The Agincourt Health and Demographic Surveillance System (HDSS) in north-eastern South Africa is served by eight public primary healthcare facilities. Since 2014, HIV patient visits are logged electronically at these clinics, with patient records individually linked to their HDSS record. These data were used to generate a list of patients >90 days late for their last scheduled clinic visit and deemed lost to follow-up (LTFU). Patient outcomes were ascertained through a review of the TIER.Net database, physical patient files, registers kept by two non-government organizations that assist with patient tracing, cross-referencing with the HDSS records and supplementary physical tracing. Descriptive statistics were used to compare patient outcomes reported in TIER.Net to their outcome ascertained in the study.Results: Of 1,074 patients that were eligible for this analysis, TIER.Net classified 533 (49.6%) as LTFU, 80 (7.4%) as deceased, and 186 (17.3%) as transferred out. TIER.Net misclassified 36% of patient outcomes, overestimating LTFU and underestimating mortality and transfers out. TIER.Net missed 40% of deaths and 43% of transfers out. Patients categorized as LTFU in TIER.Net were more likely to be misclassified than patients classified as deceased or transferred out.Discussion: Misclassification of patient outcomes in TIER.Net has consequences for programme forecasting, monitoring and evaluation. Undocumented transfers accounted for the majority of misclassification, suggesting that the transfer process between clinics should be improved for more accurate reporting of patient outcomes. Processes that lead to correct classification of patient status including patient tracing should be strengthened. Clinics could cross-check all available data sources before classifying patients as LTFU. Programme evaluators and modelers could consider using correction factors to improve estimates of outcomes from TIER.Net.

Climatic correlates of migrant Natal long-fingered bat (Miniopterus natalensis) phenology in north-eastern South Africa

Abstract ContextFor migratory animals, particularly those with long generation times, changing weather patterns may cause a mismatch between periods of expected and actual resource availability, termed phenological mismatch. The cave-dwelling Natal long-fingered bat (Miniopterus natalensis) is a regional migrant within South Africa for which the (hitherto unknown) phenology of migration may be affected by climate. AimsTo investigate the migration phenology of the Natal long-fingered bat in relation to climate at a maternity cave in South Africa. MethodsFive years (2014–18) of echolocation data from a maternity cave site in Limpopo, South Africa, were studied. Separate stepwise General Linear Models (GLMs) were constructed for each season using photoperiod, minimum temperature, dew point, rainfall, barometric pressure, humidity and maximum wind speed. Arrival and departure dates among years were also compared. Key resultsPhotoperiod had the greatest effect on the magnitude of Natal long-fingered bat phenological patterns in activity across all seasons. Although spring (September - November) arrival at the maternity site was variable across years, summer departure dates did not differ, resulting in a shorter breeding period in the 2017–18 sample year. During the 2016–17 sample year, the magnitude of Natal long-fingered bat activity was significantly lower than in other years, which coincided with El Niño-induced drought conditions and likely impacted resources and led to a reduction in activity and population size. ConclusionsPhotoperiod is a strong predictive cue of the phenology of migration of the Natal long-fingered bat and likely cues migration for this species. The narrow departure dates of these bats from the maternity site supports these results. ImplicationsThe present study indicates that Natal long-fingered bats use photoperiod as a migration cue and do not appear to shift their spring–summer breeding season, likely making them vulnerable to phenological mismatch and population decline. The research highlights the need for systematic population monitoring for the Natal long-fingered bat.

Biomarker Responses in the Freshwater Shrimp Caridina nilotica as Indicators of Persistent Pollutant Exposure.

Biomarkers are applied as early warning indicators of organisms' exposure to pollutants. The aim of this study was to utilise a multi-biomarker approach in the freshwater shrimp Caridina nilotica (Decapoda: Atyidae) as indicators of persistent pollutant exposure. A suite of biomarkers was selected to cover oxidative stress and damage, and energetics of the organisms. Five sites, representing an agricultural and pesticide application gradient, were sampled during two flow related hydro-periods in rivers of the Phongolo floodplain, north-eastern South Africa. Cytochrome P450 (CYP) activity was significantly higher in shrimp at sites directly adjacent to regions of increased human activity. Increased oxidative responses, i.e. catalase (CAT; p < 0.01) and protein carbonyl (PC, p < 0.01) were also found at these sites. The energetics biomarker did not show any influence of increased contaminant exposure. We demonstrated that the biomarkers of exposure (CYP) and effect (CAT, PC) were suitable to detect effects of stressors, probably persistent pollutants.

A new genus and species of fish parasitic cymothoid (Crustacea, Isopoda) from the Indian Ocean coast of South Africa, with a key to the externally attaching genera of Cymothoidae

Bambalocra intwalagen. et sp. nov. is described from Sodwana Bay, north-eastern South Africa. The monotypic genus is characterised by the broadly truncate anterior margin of the head with a ventral rostrum, coxae 2–5 being ventral in position not forming part of the body outline and not or barely visible in dorsal view, and the posterolateral margins of pereonites 6 and 7 are posteriorly produced and broadly rounded. The antennulae bases are widely separated, with both antennula and antenna slender. The species is known only from the type locality and the known hosts are species of Pomacanthidae (Angelfish). A revised key to the externally attaching genera of Cymothoidae is provided.

Gymnosporia sekhukhuniensis (Celastraceae), a new species from South Africa

Gymnosporia sekhukhuniensis, a new species from north-eastern South Africa, is described, illustrated, mapped, and compared with closely related species. It belongs to Gymnosporia sect. Buxifoliae, more specifically Group 1, the members of which are characterized by the capsules being (2)3(4)-valved, rugose or verrucose, and the seeds partially covered by the aril. The new species has a restricted distribution range and is near-endemic to the Sekhukhuneland Centre of Endemism. This biogeographical region rich in restricted-range plants is more or less congruent with surface outcrops of mafic and ultramafic igneous rocks belonging to the Rustenburg Layered Suite of the eastern Bushveld Complex. The range of the new species shows marginal intrusion into the far northern part of the nearby Wolkberg Centre of Endemism, where it is associated with dolomites of the Malmani Subgroup. Gymnosporia sekhukhuniensis is a suffrutex mainly associated with rocky outcrops in open savannah. Diagnostic characters include its dwarf habit (up to 1.6 m tall), capsules that are relatively small (5–8 mm long), woody, scaly-rugose, with hard pointed apices, and leaves that are very laxly arranged on the stems, with some often present on the thorns. Also included is a key to the 10 currently accepted species in G. sect. Buxifoliae Group 1. The taxonomic significance of capsule and seed characters for demarcating sections and species in the genus Gymnosporia is emphasized.

Geoheritage of the Eastern Limb of the Bushveld Igneous Complex, South Africa: a Uniquely Exposed Layered Igneous Intrusion

The eastern limb of the Bushveld Igneous Complex outcrops in the Middleveld, a localized physiographic region of northeastern South Africa associated with an erosional embayment into the interior plateau. Superimposed drainage of the Olifants and Steelpoort Rivers has produced a mountainous terrain where the layered ultramafic-mafic rocks (“Rustenburg Layered Suite”) and metamorphic aureole outcrop in regional escarpments and arcuate ridges. Meter-thick igneous layers can be delineated for tens of kilometers. Five principal zones are recognized; each comprised of different groups of cumulates with distinctive marker layers. Orebodies such as chromitites and PGE reefs (Critical Zone) and Ti-magnetite layers (Upper Zone) are constrained to specific zones. Despite the origin of igneous layering being incompletely understood, field evidence suggests that the Rustenburg Layered Suite developed incrementally from injection of thin magma sheets. Each zone is associated with discrete lineages of parental magmas. The Merensky Reef, the most well known of the layered orebodies, has an unusual origin in that it may have crystallized from ultramafic sills that were injected into a pre-existing noritic-anorthositic substrate. The primary layering is transgressed by discordant ultramafic bodies, of which two types, dunite pipes and the unusual iron-rich ultramafic pegmatite bodies, are significant. The eastern limb has a long history of human habitation and the valleys and interior plateau are relatively densely populated. Details of the African Iron Age and history of the Sekhukhune people are preserved at the Tsate cultural center. Three pioneering geologists, Arthur Hall, Hans Merensky, and Percy Wagner, greatly advanced Bushveld geology and were involved in the 1924-9 “platinum rush.” This culminated in discovery of four platiniferous discordant pipes and the Merensky Reef. The mining heritage includes the discovery site of platinum (Mooihoek pipe), the world’s oldest underground platinum mine (Onverwacht pipe), and historical workings on the Merensky Reef (Winnaarshoek). The combination of classic outcrops of layered ultramafic-mafic rocks, together with the unique community and mining heritage, justifies establishing an eastern limb geopark.

A classification of synoptic weather patterns linked to extreme rainfall over the Limpopo River Basin in southern Africa

In the last few decades, the Limpopo River Basin (LRB) has experienced a number of extreme rainfall events which were responsible for considerable socio-economic and environmental impacts. Most of the population here is poor and dependent on rain-fed agriculture. In order to better understand these events over the LRB, CHIRPS, 0.05° gridded rainfall data are used to identify the daily extreme events, analyse their interannual variability and examine relationships with large scale climate modes over the 1981–2016 period. Analysis of the top 20 events suggests a pattern with rainfall generally decreasing from the eastern to western parts of the basin. Typically, the highest rainfall amounts occur over the regions where there are steep topographical gradients between the mountainous regions of northeastern South Africa and the Mozambican floodplains. Almost half of the top 200 extreme events are associated with tropical extra-tropical cloud bands (48%), with tropical low-pressure systems (28%), Mesoscale Convective Systems (14%), and cut-off lows (10%) in the mid-upper atmosphere, also making sizeable contributions. The monthly distribution of the events showed that most of the events occurred during the late summer months (January–March) when tropical lows and cloud bands are more common. On interannual time-scales, most of the summers with above average number of events coincide with La Nina conditions and, to lesser extent, a positive subtropical South Indian Ocean Dipole.