After extracting oil from olives a residue is left usually referred to as the olive oil processing residue (OPR). This study explores the way in which ancient societies may have used OPR as fuel for fires to generate heat and the various issues that are related to the residues of this fuel. After drying, the high heating value and structure of OPR makes it an excellent and efficient fuel. Upgrading OPR further, through thermal conversion or charring, provides an even more efficient fuel (COPR), with a hotter and smoke free flame, a higher heating value and which is lighter in mass and thus easier to transport. After a fire is extinguished two types of remains of the fuel are left i.e. char and ash. Analyses on both remains, recovered from archaeological deposits, could be used as a source of information on fuel utilization. Laboratory experiments on charred modern OPR and stones show that by measuring their reflectance and analyzing their structure under reflected light microscopy, OPR and COPR can be distinguished in the charred material recovered from three archaeological sites in Greece and Syria. Based on these investigations it is suggested that on the three sites COPR was used as fuel. Ash, sampled together with the char, provides the possibility of investigating if other types of fuel were used, apart from OPR or COPR. On the investigated sites no ash was collected, but the analysis of the modern OPR showed that the properties of its ash could be used to distinguish it from other types of fuel. Ash from modern OPR and olive stones showed the presence of phytoliths. The often discussed issue related to the sharpness and smoothness of the edges of charred fragmented olive stones was investigated. The results showed that this is not a reliable criterion for recognizing olive oil production. It is recommended that in addition to the identification of the botanical material more properties of the remains of fuels should be analysed. To prevent destroying and losing char and ash as a result of excavation activities such as flotation and sieving, special measures have to be taken. The results show that analysing char and ash may provide valuable information on the (pyro)technology practised in ancient societies.
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RBINS Staff Publications 2016
Tropical rain forests are inhabited by a wide range of plant and animal diversity. However, little is known about the diversity of ant (Hymenoptera: Formicidae) species in these areas. To fill the gap, a study has been conducted in seven sites inside Nyungwe National Park, a tropical rain forest located in South-Western Rwanda. Data have been collected in October 2021 through a quick sampling using pitfall traps, arboreal traps, baiting, Winklers, and hand searching of nests in leaf litter, soil, rotten and fallen wood, and under stones. Collected ant specimens have been identified to subfamily, genus and species levels by using the identification keys. Names of species have been confirmed after comparing the findings with the specimens housed at the Royal Belgian Institute of Natural Science (Brussels, Belgium) and at Kiko Gomez’s personal collection (Barcelona, Spain). A total of 7 subfamilies, 28 genera and 74 species were sampled. The subfamily Myrmicicnae had more genera and species compared with other subfamilies. Further, 9 genera and 43 species were collected in Rwanda for the first time, while 13 species were potentially undescribed ant species. High number of species has been sampled in the sites located in secondary forest at Karamba (53 species) and Pindura (33 species). We recommend intensive sampling in other locations of Nyungwe tropical rainforest and in the rest of Rwanda mountain tropical rain forests to get a clear view on the diversity of ant species in Rwanda.
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RBINS Staff Publications 2022
