Assessment of material characteristics of ancient concretes,Grande Aula,Markets of Trajan,Rome

The Grande Aula, or Great Hall, of the Markets of Trajan (AD 96 to 115) is an intact example of the domed, concrete architecture of imperial Rome. Petrographic, x-ray diffraction, chemical, and SEM analyses demonstrate that wall mortars contain Pozzolane Rosse volcanic ash aggregate (harenae fossiciae) and strätlingite, a complex calcium aluminate cement hydrate (C₂ ASH₈) that gives modern cements good durability and compressive strength. Specific gravity tests and a new petrographic method for assessing bulk densities indicate unit weights of about 1750 kg/m³ for the wall mortars and 1430–1640 kg/m³ for the pumice bearing, vaulted ceiling mortars. Innovative point load source tests record the tensile strengths (f_t) of the aggregate and interfacial elements of the conglomeratic concrete fabric. These suggest f_t of about 2.7 MPa for brick, 1.2 MPa for Tufo Lionato tuff, and 0.9 MPa for Tufo Giallo della Via Tiberina tuff coarse aggregate (caementa), based on a tentative, approximate correlation with splitting (Brazilian) tests. The pozzolanic mortar and interfacial zones have lower f_t in the range of 0.8 MPa to 0.5 MPa. The relatively low mortar strength and its somewhat tenuous adhesion to the coarse aggregate suggests that the caementa may have arrested the propagation of tensile microcracks that formed in the mortar, thereby increasing the composite tensile strength of the concrete. Roman builders selected the complex aggregate mixes to optimize the performance of the wall and vault concretes.     

First Obsidian in the Northern French Alps during the Early Neolithic

An exceptional discovery was made in 2013 in the northern French Alps, at the Grande Rivoire site in Sassenage (Isère department): an obsidian bladelet from Sardinia was found in a cultural horizon dated to about 5360–5210 cal b.c. The abundant arrowheads found with it are characteristic of the Early Neolithic in the South of France (Cardial/Epicardial). Yet there was no pottery or domestic fauna, and only discrete markers of farming. The typological, technological and micro-wear analysis of this bladelet, as well as the determination of the origin of the raw material, open new avenues of reflection for the neolithization of the northern Alps, in particular concerning the role played by the Early Neolithic cultures of northern Italy.     

PROJECTIONS OF RACE,NATURE, AND ETHNOGRAPHIC CHILDHOOD IN EARLY EDUCATIONAL CINEMA AT THE NATIONAL MUSEUM OF CANADA

In this article, we examine depictions of race, nature, and childhood in Harlan Ingersoll Smith's early ethnographic films at the National Museum of Canada. Created in the 1920s for a children's education programme, Smith's films construct ethnographic portraits of different Indigenous peoples in Western Canada. We demonstrate how museum education appropriated Indigeneity as a discursive resource to immerse viewing children in particular narratives of Canadian national heritage and development. The films worked through a complex double movement, bringing children in the Ottawa museum audience into association with Indigenous children based on shared experience as children while simultaneously differentiating Indigenous peoples as Other. The films inculcated white youth at the museum in a romanticized connection to Canada's prehistory through knowledge of the nation's Indigenous peoples as well as nature. In the films, the position of Indigeneity within the future remained ambiguous (traditional practices sometimes disappearing, sometimes enduring). Yet, despite Smith's uncertainty about colonial beliefs in the disappearance of Indigeneity, his films nonetheless presented the teleological development of the settler nation as certain. Our article highlights how thinking about children, as audience for and thematic focus of these films, extends discussions of the geographies of film, of children, and of settler colonial nationalism.