Fossil hailstone imprints in Mesoproterozoic (1.7 Gyr) quartzite of the Tombador Formation (Chapada Diamantina Group), Brazil

Fossil pockmarks, 2.5-4 cm in diameter, 3-8 mm deep, with raised, asymmetrical borders are preserved in Mesoproterozoic quartzite representing fluvial and eolic lithofacies of the Tombador Formation (Chapada Diamantina Group) deposited 1.7 billion years ago in what is now northeastern Brazil. Indentations created by projecting 2-4 cm diameter ice pellets into moist beach sand were of the same type - with raised, asymmetrical borders and equivalent diameters and depths – strongly supporting the hypothesis that the fossil features represent impressions of paleohailstone impacts. These well-defined and well-preserved paleohailstone impressions represent the oldest known features of their type in the world, and the first records from South America

Fatores geológicos e sociológicos que influenciam a construção e ocupação de abrigos históricos de mineração de pedra, Estado da Bahia, Brasil, 1844 – presente

The geological and sociological factors that influenced the construction and habitation of the “toca” rockshelters built and occupied by diamond miners starting in 1844 are discussed. Extensive field excursions were made into the Chapada Diamantina Mountains, in what is now the Chapada Diamantina National Park, over a period of more than 40 years to document the archaeological vestiges of the diamond rush there. A total of 650 archaeological features were identified, geo-referenced, photo-documented, and classified; 286 of those features were “toca” rockshelters and 53 were stone houses. The local geology, water resources, regional climate, and human factors dictated the construction and occupation of those shelters, including the availability of appropriate overhanging rock ledges, the proximity of potable water, site humidity, and the proximity of diamond-bearing formations. The “toca” shelters themselves share a number of common features, including fire pits, a lack of windows, construction without the use of mortar, and the avoidance of East-facing sites.Se discuten los factores geológicos y sociológicos que influyeron en la construcción y habitación de los abrigos rocosos de “toca” construidos y ocupados por los mineros de diamantes a partir de 1844. Se realizaron extensas excursiones de campo a las montañas Chapada Diamantina, en lo que ahora es el Parque Nacional Chapada Diamantina, durante un período de más de 40 años para documentar los vestigios arqueológicos de la fiebre del diamante allí. Se identificaron, georreferenciaron, fotodocumentaron y clasificaron un total de 650 elementos arqueológicos; 286 de esos elementos eran abrigos rocosos de “toca” y 53 eran casas de piedra. La geología local, los recursos hídricos, el clima regional y los factores humanos dictaron la construcción y ocupación de esos refugios, incluida la disponibilidad de salientes rocosos colgantes apropiados, la proximidad de agua potable, la humedad del sitio y la proximidad de formaciones diamantíferas. Los refugios de "toca" comparten una serie de características comunes, que incluyen fogatas, falta de ventanas, construcción sin el uso de mortero y la evitación de sitios orientados al este.São discutidos os fatores geológicos e sociológicos que influenciaram a construção e habitação dos abrigos de toca construídos e ocupados por garimpeiros a partir de 1844. Extensas excursões de campo foram feitas na Serra da Chapada Diamantina, no atual Parque Nacional da Chapada Diamantina, por um período de mais de 40 anos para documentar os vestígios arqueológicos da corrida do diamante ali. Um total de 650 feições arqueológicas foram identificadas, georreferenciadas, fotodocumentadas e classificadas; 286 dessas feições eram abrigos de toca e 53 eram casas de pedra. A geologia local, os recursos hídricos, o clima regional e os fatores humanos ditaram a construção e ocupação desses abrigos, incluindo a disponibilidade de bordas rochosas salientes adequadas, a proximidade de água potável, a umidade do local e a proximidade de formações diamantíferas. Os próprios abrigos de toca compartilham uma série de características comuns, incluindo fogueiras, falta de janelas, construção sem uso de argamassa e evitar locais voltados para o leste

First pollen survey of murundus in the Chapada Diamantina region of the state of Bahia, Brazil

This was a pollen survey, in which we analyzed the sediments and moss polsters of murundus (termite mounds) in the Chapada Diamantina region of the state of Bahia, Brazil. Palynological treatment revealed the presence of 53 pollen types in murundus sediments, of which 23 were related to plants in the semi-arid zone and 30 remained unidentified. In moss polster samples, the pollen assemblage comprised 42 pollen types for which taxonomic affinities were identified and 54 for which they were not. In our comparison of the two pollen assemblages, we found that moss polsters and murundu sediments shared 15 pollen types. For some of the pollen grains in the murundus sediments, it was not possible to make reliable interpretations because of small number of grains and the poor state of conservation. In contrast, the pollen analyses of the moss polster samples showed that they could represent a useful tool for studies of pollen rain. To our knowledge, this is the first study of murundus as natural pollen collectors. Our findings suggest new possibilities for the use of the pollen records preserved in termite mounds